This chapter covers learning outcomes related to fundamental electrical installation operations. It discusses basic electrical circuits including power circuits, lighting circuits, and the use of junction boxes. The chapter also covers health and safety considerations when performing electrical work, including proper personal protective equipment. It introduces common electrical hand tools and their safe use and maintenance. The risks associated with electrical work are assessed using the ERIC PD method to control risks through elimination, replacement, isolation, controls, PPE, and development.
A substation is an important part of an electrical power system where voltage is transformed from high to low levels or vice versa. Electric power may pass through multiple substations between generation and consumption. Main components of a substation include transformers to step up or down voltages, circuit breakers, switches, protective relays, surge arrestors, and other equipment. Substations can be indoor, outdoor, underground or pole-mounted depending on construction, and serve purposes like transmission, distribution, power factor correction or frequency changing. Careful consideration is given to site selection, environmental factors and layout of a substation.
This is the simple ppt explaining about the main components of the power systems. especially we are determining the insulators and its types with real time pictures which are attractive,
A substation receives power transmitted at high voltage from a generating station and transforms the voltage to a level appropriate for local use. It consists of transformers, switches, circuit breakers and other equipment to step up or step down voltages. Typical components include busbars to carry current, disconnectors and circuit breakers to connect and disconnect circuits, current and voltage transformers to detect and transform measurements, earthing switches for safety, and surge arrestors to protect from surges. Substations can be classified by their function, such as transformer or industrial substations, or by their control method, such as manual, automatic or supervisory control.
The document summarizes the setup of a 132kv substation with 3 incoming transmission lines and 1 outgoing line. It has 2 transformers that step down the voltage from 132kv to 33kv to feed a 33kv substation. The substation contains circuit breakers, isolators, transformers, capacitor banks, and other equipment to regulate voltage and distribute power safely throughout the electrical network.
Distribution boards and Protection devices pptZuhairQadri
This document discusses distribution boards and protection devices for electrical installations. It provides information on 3-phase power systems, distribution boards, protection and location of distribution boards, overcurrent protection including fuses and circuit breakers, and characteristics of fuses and miniature circuit breakers. Distribution boards contain circuit breakers and fuses to distribute power to circuits while protecting against overloads and faults. Proper location and enclosure is important for safety. Fuses and circuit breakers each have specific current and time ratings to provide discrimination of protection.
This document provides an overview of transformers, including their structure, working principle, construction, losses, and applications. Transformers are devices that change AC electric power at one voltage level to another through magnetic coupling of two coils. They allow interchange of electric energy between circuits without a direct connection. The transformer consists of a primary coil, secondary coil, and magnetic core. When an alternating current flows through the primary, it induces a changing magnetic flux that is transferred to the secondary coil to induce voltage. Transformers experience losses from copper, hysteresis, and eddy currents. They are used widely in power transmission and applications like televisions and cameras.
This case study describes the key components of an electric transmission substation. It discusses transformers that change voltage levels, conductors that transmit electricity, insulators that prevent arcing, isolators for safety during maintenance, busbars for distributing power, lightning arresters for overvoltage protection, and circuit breakers for interrupting faults. The document provides details on the working principles and applications of these various substation equipment.
This document provides information about earthing systems including their purposes, specifications, types, and maintenance. The key points are:
1) Earthing systems are used to protect lives and equipment from electrical shock by providing a safe path for currents to travel and ensuring conductive parts do not reach dangerous potentials.
2) Recommended earth resistance values vary based on the equipment, with substations requiring lower values like 0.5-2 ohms and individual devices like poles needing 5-10 ohms.
3) Common earthing types include pipe, plate, strip, and rod systems, with factors like soil conditions determining which type is best. Pipe earthing using galvanized iron pipes 10 feet long is very
A substation is an important part of an electrical power system where voltage is transformed from high to low levels or vice versa. Electric power may pass through multiple substations between generation and consumption. Main components of a substation include transformers to step up or down voltages, circuit breakers, switches, protective relays, surge arrestors, and other equipment. Substations can be indoor, outdoor, underground or pole-mounted depending on construction, and serve purposes like transmission, distribution, power factor correction or frequency changing. Careful consideration is given to site selection, environmental factors and layout of a substation.
This is the simple ppt explaining about the main components of the power systems. especially we are determining the insulators and its types with real time pictures which are attractive,
A substation receives power transmitted at high voltage from a generating station and transforms the voltage to a level appropriate for local use. It consists of transformers, switches, circuit breakers and other equipment to step up or step down voltages. Typical components include busbars to carry current, disconnectors and circuit breakers to connect and disconnect circuits, current and voltage transformers to detect and transform measurements, earthing switches for safety, and surge arrestors to protect from surges. Substations can be classified by their function, such as transformer or industrial substations, or by their control method, such as manual, automatic or supervisory control.
The document summarizes the setup of a 132kv substation with 3 incoming transmission lines and 1 outgoing line. It has 2 transformers that step down the voltage from 132kv to 33kv to feed a 33kv substation. The substation contains circuit breakers, isolators, transformers, capacitor banks, and other equipment to regulate voltage and distribute power safely throughout the electrical network.
Distribution boards and Protection devices pptZuhairQadri
This document discusses distribution boards and protection devices for electrical installations. It provides information on 3-phase power systems, distribution boards, protection and location of distribution boards, overcurrent protection including fuses and circuit breakers, and characteristics of fuses and miniature circuit breakers. Distribution boards contain circuit breakers and fuses to distribute power to circuits while protecting against overloads and faults. Proper location and enclosure is important for safety. Fuses and circuit breakers each have specific current and time ratings to provide discrimination of protection.
This document provides an overview of transformers, including their structure, working principle, construction, losses, and applications. Transformers are devices that change AC electric power at one voltage level to another through magnetic coupling of two coils. They allow interchange of electric energy between circuits without a direct connection. The transformer consists of a primary coil, secondary coil, and magnetic core. When an alternating current flows through the primary, it induces a changing magnetic flux that is transferred to the secondary coil to induce voltage. Transformers experience losses from copper, hysteresis, and eddy currents. They are used widely in power transmission and applications like televisions and cameras.
This case study describes the key components of an electric transmission substation. It discusses transformers that change voltage levels, conductors that transmit electricity, insulators that prevent arcing, isolators for safety during maintenance, busbars for distributing power, lightning arresters for overvoltage protection, and circuit breakers for interrupting faults. The document provides details on the working principles and applications of these various substation equipment.
This document provides information about earthing systems including their purposes, specifications, types, and maintenance. The key points are:
1) Earthing systems are used to protect lives and equipment from electrical shock by providing a safe path for currents to travel and ensuring conductive parts do not reach dangerous potentials.
2) Recommended earth resistance values vary based on the equipment, with substations requiring lower values like 0.5-2 ohms and individual devices like poles needing 5-10 ohms.
3) Common earthing types include pipe, plate, strip, and rod systems, with factors like soil conditions determining which type is best. Pipe earthing using galvanized iron pipes 10 feet long is very
This document discusses various types of wiring accessories and lighting used in domestic and commercial wiring. It describes common accessories like switches, sockets, plugs, lamp holders and safety devices like fuses and miniature circuit breakers. It also covers different types of lighting including incandescent, fluorescent, LED lights and discusses ambient, task and accent lighting. Various fixtures like pendants, chandeliers, track lighting and lanterns are also mentioned.
This presentation provides an overview of substations, including their classification, components, and functions. It discusses the different types of substations such as transformer substations, pole-mounted substations, and underground substations. Transformer substations are classified as step-up, primary grid, secondary, and distribution substations based on their voltage levels. Pole-mounted substations are constructed on poles for distribution. Underground substations are used in congested areas with limited space. The presentation also describes key equipment in substations like circuit breakers, transformers, isolators, and their protective functions.
The document discusses the design considerations for electrical installations. It covers topics like supply systems, distribution systems, conductors and cables, protection devices, earthing, and circuit breakers. The key points are:
1) Electrical supply systems are classified based on voltage into LV, MV, HV and EHV ranges. Distribution systems can be single or three-phase using 2, 3 or 4-wire configurations.
2) Selection of cables considers current rating, voltage drop and insulation ability to withstand temperatures. Stranded conductors improve flexibility. Fuses and circuit breakers protect against overloads, short circuits and earth faults.
3) Earthing is important for safety and connects earth terminals to electrodes buried in
This document summarizes key topics in electrical distribution systems, including receptacle types and testing, voltage measurements, current measurements, circuit breakers and fuses, power quality issues, and transformer types. Receptacles, panels, fuses, circuit breakers, temperature problems, power quality, and transformers are discussed. Proper testing and measurements are described to evaluate receptacles, voltages, currents, power quality, and transformers.
Underground cables are used to transmit power over long distances. They are laid in trenches below ground for safety and aesthetic reasons. Some key advantages of underground cables include reduced damage from weather, higher transmission efficiency due to insulation, and less required maintenance. Cables must be designed with stranded conductors, adequate insulation thickness, and mechanical protection. They are classified based on voltage level, number of cores, construction, and insulation material. Proper handling, storage, inspection, and laying of cables in trenches is important to prevent damage and ensure long service life.
An alternator is an electrical generator that converts mechanical energy to electrical energy. It uses a rotating magnetic field with a stationary armature. The working principle relies on Faraday's law of electromagnetic induction. As the armature rotates within the magnetic field, an alternating current is produced. The main components are the stator with stationary armature windings and the rotor with a rotating magnetic field supplied by a DC current. Armature reaction causes the magnetic field to be distorted by the armature current. Alternators have various applications including in automobiles, power plants, and for providing regenerative braking in induction motors. Induction generators can also be used to convert the rotational energy of windmills into electrical energy.
The document discusses electrical wiring systems used in buildings. It describes different types of wiring such as cleat wiring, wood casing wiring, CTS wiring, conduit wiring, and metal sheathed wiring. It covers topics like wire selection criteria based on current and voltage ratings, wire insulation materials, and Indian Standards for electrical wiring installations. Color coding of wires is also mentioned.
The document discusses different types of electrical insulators used in power transmission and distribution systems. It describes pin insulators, which are used for voltages up to 33kV and secure the conductor to cross-arms on poles. For higher voltages, suspension insulators are used, consisting of multiple porcelain discs connected in series. Strain insulators are used where there are sharp turns or high tension, using assemblies of suspension insulators or shackle insulators for lower voltages. Each type of insulator is designed to support and isolate electrical conductors without allowing current flow.
This document discusses different types of wires and cables used in electrical installations. It describes six main types of wires: VIR, TRS, PVC, lead alloy sheathed, weather proof, and flexible wires. PVC wire is most commonly used due to its moisture proof, tough, and durable properties. Cables are assemblies of two or more conductors held together with an overall sheath. Cables are classified based on voltage level and insulation material into low tension, medium/high tension, belted, screened, super tension, oil filled, and gas pressure cables.
This document summarizes different types of turbines used to generate hydroelectric power. It describes impulse turbines like the Pelton wheel and cross-flow turbine, which use the velocity of water to turn the runner. Reaction turbines like the Francis turbine and propeller turbine develop power from both pressure and moving water. Kinetic turbines generate electricity from the kinetic energy in flowing water sources like rivers and ocean currents without requiring diversion of water through pipes. The document provides details on the basic design and operation of each turbine type as well as factors to consider like head, flow, and efficiency.
This document discusses various electrical components and circuits. It defines a circuit as a closed path that current can flow through. It describes galvanometers, which measure current, and how ampermeters and voltmeters are derived from galvanometers. It also discusses Ohm's Law, Kirchhoff's Laws, power in circuits, and different types of circuits including series, parallel and DC circuits.
basic electrical and electronics engg. components of LT switch gear, switch fuse unit, MCB, MCCB, ELCB, TYPES OF WIRES AND CABLES, ELECTRICAL EARTHING, TYPES OF BATTERIES,
VTU Notes for Testing and commissioning of Electrical Equipment Department of Electrical and Electronics Faculty Name: Mrs Veena Bhat Designation: Assistant Professor Subject: Testing and Commissioning of Electrical equipment Semester: VII
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
This document provides information on various types of equipment used in electrical substations and their functions:
- Lightning arrestors protect the substation from high voltages by pulling lightning to ground.
- Current and potential transformers step down high voltages and currents to measurable levels for monitoring and protection.
- A wave trap traps unwanted waves on incoming feeders.
- A circuit breaker automatically breaks the circuit during faults to prevent equipment damage.
- Transformers step down transmission line voltages within the substation for distribution.
The document discusses different types of induction furnaces, including direct core type, vertical core type (Ajax-Wyatt), and coreless type furnaces. It explains their basic constructions and operating principles. The vertical core type furnace (Ajax-Wyatt) aims to eliminate the limitations of direct core type furnaces by using a V-shaped design that helps prevent discontinuity in the secondary circuit. Coreless furnaces have no iron core and use high frequency supply to induce eddy currents directly in the charge for heating.
The document discusses factors to consider when installing transmission lines, including:
1. Choosing the best route based on possible future power demands, suitable right-of-way, and climate.
2. Considering topography, accessibility, and right-of-way costs for the most economic route.
3. Classifying transmission line systems as single lines, parallel lines, radial lines, ring systems, or networks.
Electrical wiring is the process of connecting cables and wires from various devices like lights, fans, switches, and sockets to the main distribution board for continuous power supply. There are different types of electrical wiring systems including cleat wiring, wooden casing and capping wiring, CTS or TRS or PVC sheath wiring, lead sheathed or metal sheathed wiring, and conduit wiring. Conduit wiring can be surface or open conduit wiring or concealed or underground conduit wiring depending on where steel or PVC pipes are used to run the wires. Buildings come in different types including residential for personal houses, industrial for companies, and workshops for product manufacturing.
This document discusses power cable installation methods. It covers various topics such as:
1. Underground installation methods including direct laying, draw in system, and solid system. Direct laying is the most common but has faults that can be difficult to locate.
2. Overhead installation including considerations for sag and tension based on span length, weight, and temperature as well as ice and wind loading.
3. Installation in conduit including determining appropriate conduit size based on clearance, jamming ratios, and fill percentages.
4. IEC 60364 provides guidance on installation methods for different conductor and cable types including without fixings, clipped direct, and conduit systems.
Basic Safety Procedure in High Risk Activities and IndustriesJames Tolentino
The document provides guidance on safety procedures for hazardous activities and industries. It discusses different types of hazardous energy including electrical, chemical, mechanical, hydraulic, pneumatic and thermal energy. It outlines the steps to develop a hazardous energy control program which includes gathering information, performing task and hazard analyses, implementing controls, and training employees. It also discusses lockout/tagout procedures and provides electrical safety tips for construction workers.
Arc flash incidents can be costly in terms of personnel injury and equipment repair/replacement. This presentation provides an overview of the NFPA 70E 2012 Standard for Electrical Safety in the Workplace and the requirements of the standards, which are intended to better protect electrical workers from injury when they work on energized electrical equipment. This includes all aspects of facility and employer responsibilities for compliance to the NFPA 70E standards, as well as the current status of OSHA enforcement of these standards. Copyright AIST Reprinted with Permission.
This document discusses various types of wiring accessories and lighting used in domestic and commercial wiring. It describes common accessories like switches, sockets, plugs, lamp holders and safety devices like fuses and miniature circuit breakers. It also covers different types of lighting including incandescent, fluorescent, LED lights and discusses ambient, task and accent lighting. Various fixtures like pendants, chandeliers, track lighting and lanterns are also mentioned.
This presentation provides an overview of substations, including their classification, components, and functions. It discusses the different types of substations such as transformer substations, pole-mounted substations, and underground substations. Transformer substations are classified as step-up, primary grid, secondary, and distribution substations based on their voltage levels. Pole-mounted substations are constructed on poles for distribution. Underground substations are used in congested areas with limited space. The presentation also describes key equipment in substations like circuit breakers, transformers, isolators, and their protective functions.
The document discusses the design considerations for electrical installations. It covers topics like supply systems, distribution systems, conductors and cables, protection devices, earthing, and circuit breakers. The key points are:
1) Electrical supply systems are classified based on voltage into LV, MV, HV and EHV ranges. Distribution systems can be single or three-phase using 2, 3 or 4-wire configurations.
2) Selection of cables considers current rating, voltage drop and insulation ability to withstand temperatures. Stranded conductors improve flexibility. Fuses and circuit breakers protect against overloads, short circuits and earth faults.
3) Earthing is important for safety and connects earth terminals to electrodes buried in
This document summarizes key topics in electrical distribution systems, including receptacle types and testing, voltage measurements, current measurements, circuit breakers and fuses, power quality issues, and transformer types. Receptacles, panels, fuses, circuit breakers, temperature problems, power quality, and transformers are discussed. Proper testing and measurements are described to evaluate receptacles, voltages, currents, power quality, and transformers.
Underground cables are used to transmit power over long distances. They are laid in trenches below ground for safety and aesthetic reasons. Some key advantages of underground cables include reduced damage from weather, higher transmission efficiency due to insulation, and less required maintenance. Cables must be designed with stranded conductors, adequate insulation thickness, and mechanical protection. They are classified based on voltage level, number of cores, construction, and insulation material. Proper handling, storage, inspection, and laying of cables in trenches is important to prevent damage and ensure long service life.
An alternator is an electrical generator that converts mechanical energy to electrical energy. It uses a rotating magnetic field with a stationary armature. The working principle relies on Faraday's law of electromagnetic induction. As the armature rotates within the magnetic field, an alternating current is produced. The main components are the stator with stationary armature windings and the rotor with a rotating magnetic field supplied by a DC current. Armature reaction causes the magnetic field to be distorted by the armature current. Alternators have various applications including in automobiles, power plants, and for providing regenerative braking in induction motors. Induction generators can also be used to convert the rotational energy of windmills into electrical energy.
The document discusses electrical wiring systems used in buildings. It describes different types of wiring such as cleat wiring, wood casing wiring, CTS wiring, conduit wiring, and metal sheathed wiring. It covers topics like wire selection criteria based on current and voltage ratings, wire insulation materials, and Indian Standards for electrical wiring installations. Color coding of wires is also mentioned.
The document discusses different types of electrical insulators used in power transmission and distribution systems. It describes pin insulators, which are used for voltages up to 33kV and secure the conductor to cross-arms on poles. For higher voltages, suspension insulators are used, consisting of multiple porcelain discs connected in series. Strain insulators are used where there are sharp turns or high tension, using assemblies of suspension insulators or shackle insulators for lower voltages. Each type of insulator is designed to support and isolate electrical conductors without allowing current flow.
This document discusses different types of wires and cables used in electrical installations. It describes six main types of wires: VIR, TRS, PVC, lead alloy sheathed, weather proof, and flexible wires. PVC wire is most commonly used due to its moisture proof, tough, and durable properties. Cables are assemblies of two or more conductors held together with an overall sheath. Cables are classified based on voltage level and insulation material into low tension, medium/high tension, belted, screened, super tension, oil filled, and gas pressure cables.
This document summarizes different types of turbines used to generate hydroelectric power. It describes impulse turbines like the Pelton wheel and cross-flow turbine, which use the velocity of water to turn the runner. Reaction turbines like the Francis turbine and propeller turbine develop power from both pressure and moving water. Kinetic turbines generate electricity from the kinetic energy in flowing water sources like rivers and ocean currents without requiring diversion of water through pipes. The document provides details on the basic design and operation of each turbine type as well as factors to consider like head, flow, and efficiency.
This document discusses various electrical components and circuits. It defines a circuit as a closed path that current can flow through. It describes galvanometers, which measure current, and how ampermeters and voltmeters are derived from galvanometers. It also discusses Ohm's Law, Kirchhoff's Laws, power in circuits, and different types of circuits including series, parallel and DC circuits.
basic electrical and electronics engg. components of LT switch gear, switch fuse unit, MCB, MCCB, ELCB, TYPES OF WIRES AND CABLES, ELECTRICAL EARTHING, TYPES OF BATTERIES,
VTU Notes for Testing and commissioning of Electrical Equipment Department of Electrical and Electronics Faculty Name: Mrs Veena Bhat Designation: Assistant Professor Subject: Testing and Commissioning of Electrical equipment Semester: VII
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
This document provides information on various types of equipment used in electrical substations and their functions:
- Lightning arrestors protect the substation from high voltages by pulling lightning to ground.
- Current and potential transformers step down high voltages and currents to measurable levels for monitoring and protection.
- A wave trap traps unwanted waves on incoming feeders.
- A circuit breaker automatically breaks the circuit during faults to prevent equipment damage.
- Transformers step down transmission line voltages within the substation for distribution.
The document discusses different types of induction furnaces, including direct core type, vertical core type (Ajax-Wyatt), and coreless type furnaces. It explains their basic constructions and operating principles. The vertical core type furnace (Ajax-Wyatt) aims to eliminate the limitations of direct core type furnaces by using a V-shaped design that helps prevent discontinuity in the secondary circuit. Coreless furnaces have no iron core and use high frequency supply to induce eddy currents directly in the charge for heating.
The document discusses factors to consider when installing transmission lines, including:
1. Choosing the best route based on possible future power demands, suitable right-of-way, and climate.
2. Considering topography, accessibility, and right-of-way costs for the most economic route.
3. Classifying transmission line systems as single lines, parallel lines, radial lines, ring systems, or networks.
Electrical wiring is the process of connecting cables and wires from various devices like lights, fans, switches, and sockets to the main distribution board for continuous power supply. There are different types of electrical wiring systems including cleat wiring, wooden casing and capping wiring, CTS or TRS or PVC sheath wiring, lead sheathed or metal sheathed wiring, and conduit wiring. Conduit wiring can be surface or open conduit wiring or concealed or underground conduit wiring depending on where steel or PVC pipes are used to run the wires. Buildings come in different types including residential for personal houses, industrial for companies, and workshops for product manufacturing.
This document discusses power cable installation methods. It covers various topics such as:
1. Underground installation methods including direct laying, draw in system, and solid system. Direct laying is the most common but has faults that can be difficult to locate.
2. Overhead installation including considerations for sag and tension based on span length, weight, and temperature as well as ice and wind loading.
3. Installation in conduit including determining appropriate conduit size based on clearance, jamming ratios, and fill percentages.
4. IEC 60364 provides guidance on installation methods for different conductor and cable types including without fixings, clipped direct, and conduit systems.
Basic Safety Procedure in High Risk Activities and IndustriesJames Tolentino
The document provides guidance on safety procedures for hazardous activities and industries. It discusses different types of hazardous energy including electrical, chemical, mechanical, hydraulic, pneumatic and thermal energy. It outlines the steps to develop a hazardous energy control program which includes gathering information, performing task and hazard analyses, implementing controls, and training employees. It also discusses lockout/tagout procedures and provides electrical safety tips for construction workers.
Arc flash incidents can be costly in terms of personnel injury and equipment repair/replacement. This presentation provides an overview of the NFPA 70E 2012 Standard for Electrical Safety in the Workplace and the requirements of the standards, which are intended to better protect electrical workers from injury when they work on energized electrical equipment. This includes all aspects of facility and employer responsibilities for compliance to the NFPA 70E standards, as well as the current status of OSHA enforcement of these standards. Copyright AIST Reprinted with Permission.
This document discusses arc flash hazards and NFPA 70E standards for electrical safety. It provides the following key points:
1. Arc flashes produce extremely high temperatures that can cause severe burns and pressure waves. Following NFPA 70E standards helps protect workers from arc flash injuries.
2. NFPA 70E requires hazard analyses to determine shock, flash boundaries and personal protective equipment requirements. Employers must implement electrical safety programs, train workers, and ensure only qualified personnel work on live equipment.
3. Analyses consider incident energy levels, fault currents and clearing times to determine appropriate protective boundaries and PPE. Proper work procedures and well-maintained equipment help prevent arc flash incidents.
Webinar - Electrical Arc Flash Hazards - Is your company in compliance?Leonardo ENERGY
This course is designed to equip the electrical consultant, system designer or any other professional responsible for designing or modernizing commercial and industrial electrical power distribution systems with the fundamentals of the Arc Flash Energy phenomenon.
Five to 10 arc flash explosions occur daily in the US, often severely injuring workers. The document discusses arc flash hazards, describing the intense heat, pressure, and dangers of arc flashes. It outlines standards from OSHA, NFPA, and IEEE to protect workers through analyzing hazards, establishing personal protective equipment requirements, and enforcing safety practices. The analysis process calculates incident energy levels and flash protection boundaries to determine the appropriate PPE category and safely work near energized equipment.
Lockout Tagout (LOTO) plays and important role when working with electrical equipment, electrical circuits, and electrical conductors. For more details, visit now!
NFPA 70E is a standard that covers electrical safety in the workplace. It addresses hazards like arc flash and provides guidelines for hazard analysis, personal protective equipment, and safe work practices. The standard requires justification for working on energized equipment and that equipment be de-energized whenever possible. It also provides definitions for terms like arc flash, incident energy, and flash protection boundary. Employers must conduct arc flash hazard analyses before work is done and select appropriate PPE based on incident energy calculations. Following NFPA 70E helps protect workers and reduces injuries, downtime, fines and liability from electrical accidents.
Five to 10 arc flash explosions occur daily in the US, often requiring specialized burn treatment. There are two types of faults that can cause arcs: bolted faults where current flows through a solid connection, and arcing faults where current arcs through ionized air. Arcing faults are more dangerous as the energy is released into the environment. Standards like NFPA 70E and OSHA requirements aim to protect workers by enforcing safety practices like arc flash analyses and requiring personal protective equipment suitable for the estimated incident energy levels. Proper maintenance and use of protective equipment can reduce arc flash exposure hazards.
Safety Precautions for Electrician Services.pptxRenuka581330
Electrical services are provided by electricians for installing, maintaining, and repairing electrical systems. Electrical services include installations, ceiling fans, outdoor lighting, wiring upgrades, circuit breaker replacements, whole house surge protectors, GFCI outlet installation, child-proof outlets, and more. Our expert residential, commercial & industrial electricians can provide these services and emergency services at reasonable prices anywhere in Hyderabad.
This training module provides additional electrical safety training for non-electrical skilled workers who may encounter electrical hazards in the workplace. It reviews basic electrical safety topics from a prerequisite training, and covers specific hazards like shock, arc, and blast. It discusses requirements from NFPA 70E for working near electrical equipment, and safe practices for lockout/tagout, ground fault circuit interrupters, circuit breakers, portable electric tools, extension cords, batteries, and excavating near electrical systems. The goal is to help non-electrical workers recognize and safely mitigate electrical hazards.
Safety Precautions for Electrician Services.pdfRenuka581330
Electrical services are provided by electricians for installing, maintaining, and repairing electrical systems. Electrical services include installations, ceiling fans, outdoor lighting, wiring upgrades, circuit breaker replacements, whole house surge protectors, GFCI outlet installation, child-proof outlets, and more. Our expert residential, commercial & industrial electricians can provide these services and emergency services at reasonable prices anywhere in Hyderabad.
What is arc flash? What are the legal requirements? What are the arc flash standards required in industry? Premium Power, an electrical engineering consultancy offers a checklist of what needs to be considered before carrying out work on or near live equipment
1. What is arc flash
2. OSHA, NFPA 70E
3. Codes and standards
4. Protective clothing and equipment
5. Prevention
An arc flash (or arc blast) is a type of electrical explosion that results from a low impedance connection to ground or another voltage phase in an electrical system
Even without electrocution, death or dismemberment may occur through an intense arc blast, up to 35,000 F deg, and force up to 2100 psi from the intense heat rapidly expanding the air, copper & particles creating a shockwave blast. Droplets of molten metal and shrapnel can penetrate the body.
An arc flash is a dangerous event that occurs due to an arcing fault in an electrical system, which can release tremendous heat energy and cause severe burns, injuries or death. Proper personal protective equipment is required depending on the calculated incident energy level at different locations. Regular maintenance, worker training and safety programs are important to reduce arc flash hazards by preventing faults and minimizing exposure times.
Live-line maintenance involves maintaining electrical equipment while energized and can be performed using hotstick or barehand techniques. The history of live-line tools began in 1916 with the introduction of electrical hooks for tapping energized circuits. Over time, live-line tools evolved and were accepted for higher voltages, from 34kV initially up to 345-769kV today. Live-line maintenance requires following safety precautions like calculating minimum approach distances, using protective clothing and equipment, and having multiple workers present for high voltage work.
Live-line maintenance involves maintaining electrical equipment while energized and includes barehand and hotstick techniques. Historically, live-line tools were introduced in 1916 and fiberglass poles in 1959, allowing work on higher voltages. Key terms include barehand technique (worker at conductor potential), hotstick technique (worker grounded), and minimum approach distance. Workers are positioned using insulated booms and ladders to maintain the minimum distance. Different maintenance methods include helicopter and climbing/swinging. General precautions include calculating distances, coordinating protection, using eye protection for arcs, having multiple workers, and postponing for weather.
The document discusses arc flash hazards, describing that arc flashes occur frequently in the US and can cause severe burns. It explains the differences between bolted and arcing faults, lists various standards to protect workers from arc flash like OSHA, NFPA 70E, and IEEE 1584, and describes how to perform an arc flash analysis to determine appropriate personal protective equipment.
This document discusses lockout/tagout (LOTO) procedures and regulations. It notes that craft workers, electricians, machine operators, and laborers face the greatest risk of injury from servicing energized equipment. It provides examples of hazardous energy sources and discusses OSHA regulations regarding contractor LOTO procedures and prohibiting work in proximity to energized electrical circuits. The document discusses common causes of electrical deaths like changing fluorescent lighting ballasts and presents case studies of accidents that occurred due to failures to properly de-energize equipment. It emphasizes the importance of LOTO programs and procedures to isolate, lockout, and tagout all energy sources before servicing equipment.
The document discusses electrical safety standards and best practices from NFPA 70E. It covers statistics on electrical injuries and fatalities to emphasize the importance of safety. NFPA 70E requirements are summarized, including establishing electrically safe work conditions, approach boundaries for live parts, protective equipment, hazard analysis, documentation and training. The presentation emphasizes creating an electrically safe work environment by de-energizing whenever possible, and having proper documentation, coordination and PPE for any justified live work.
This document provides an overview of heat pump systems, including:
- Heat pumps use a refrigeration cycle to convert low temperature heat to higher temperature heat.
- Common heat sources are air, ground, and water. Suitable emitters include underfloor heating and tank-in-tank water cylinders.
- Heat pumps can provide 300-500% more energy output than electrical input, with efficiencies described as Coefficient of Performance.
This document provides guidance on electrical safety in dwellings as required by Part P of the Building Regulations. It outlines the technical requirements for electrical work in dwellings, defines the scope of Part P and what work is considered notifiable, and describes the certification, inspection and testing processes for electrical work.
This document provides guidance on complying with regulations related to combustion appliances and fuel storage systems in England and Wales. It covers requirements for air supply, flues, hearths, protection from fire, warning of carbon monoxide release, and liquid fuel storage. The document gives guidance on materials, ventilation, construction methods, installation, and other provisions to ensure appliances are safely installed and operated. It also outlines the responsibilities of those involved in building work and provides checklists and examples to demonstrate compliance.
This document provides guidance on the Building Regulations 2010 concerning drainage and waste disposal in the United Kingdom. It outlines the key requirements for foul water drainage systems, wastewater treatment systems, rainwater drainage, building over sewers, and solid waste storage. The guidance covers topics such as pipe layout and sizing, pumping installations, protection from settlement, materials, testing, and maintenance of drainage systems. It also addresses repairs and alterations to existing drains and connection to public sewer systems.
This document provides information about The Building Regulations 2010 Approved Document G: Sanitation, hot water safety and water efficiency. It outlines where copies of the Approved Document can be purchased. It also summarizes some of the main changes made in the 2010 edition compared to previous editions, including new requirements for water efficiency in dwellings, enhanced provisions for hot water supply safety, and requirements for sanitary conveniences and washing facilities. The document notes that the 2010 edition incorporates further amendments made in the same year.
This document summarizes the main changes to the Building Regulations 2010 regarding ventilation requirements. The key changes include new requirements for commissioning and air flow testing of mechanical ventilation systems, providing information to building owners on system maintenance, and increased ventilation provisions for very airtight dwellings. Technical guidance was also updated, including increasing the minimum passive stack ventilator size, clarifying ventilation when bathrooms/kitchens are refurbished, and referencing a new domestic ventilation compliance guide.
This document summarizes The Building Regulations 2010 document. It contains 3 key points:
1) It provides guidance on complying with the energy efficiency requirements and regulation 7 of the Building Regulations 2010 for England and Wales. This includes requirements for new dwellings to meet targets for limiting carbon dioxide emissions.
2) It describes the general provisions, including definitions, types of work covered, exemptions, methods of demonstrating compliance, and notifying building work.
3) It outlines 5 criteria for achieving compliance: 1) meeting carbon dioxide emission rate targets, 2) following limits for building fabric and system efficiencies, 3) limiting solar gain in summer, 4) ensuring building performance is consistent with specifications, and 5)
The document discusses rainwater harvesting and greywater reuse systems. It describes how rainwater harvesting collects rainwater from roofs to use for non-potable purposes like gardening and flushing toilets in order to reduce water usage. Greywater reuse systems collect wastewater from laundry, dishwashing, and bathing for similar non-potable reuse after treatment. The document covers installation considerations and regulations for setting up these types of environmental technology systems.
The document discusses several UK environmental protection acts and regulations:
- The Environmental Protection Act 1990 defines the structure for waste management and emissions control. It covers waste disposal, contaminated land, and genetically modified organisms.
- The Hazardous Waste Regulations aim to reduce hazardous waste generation and properly manage such waste.
- The Pollution Prevention and Control Act 1999 controls industries that emit significant pollution to all environmental media.
- The Waste Electrical and Electronic Equipment Regulations require proper treatment and disposal of electronic waste without environmental harm.
This document provides information on rainwater harvesting and greywater reuse systems. It discusses the basic principles of how these systems work to collect and store rainwater and greywater for non-potable uses. The document also outlines the key regulatory requirements and installation considerations for these systems in the UK, as well as typical advantages and disadvantages.
This document discusses micro-hydroelectric power systems. It explains that small-scale hydropower can provide clean electricity generation for homes using flowing water from streams or rivers. The key components of a micro-hydro system are described, including an intake, penstock, turbine, generator, and tailrace. Equations are provided to calculate the mechanical and electrical power output based on factors like flow rate, head, and system efficiencies. Advantages are reliable renewable energy without emissions, while disadvantages include high initial costs and limited expansion options.
Micro-CHP, or micro combined heat and power, is a technology that generates electricity and heat simultaneously for individual homes or buildings. It works by using a fuel like natural gas to power a system, such as a Stirling engine, to produce both electricity and hot water. Micro-CHP systems typically produce around 1kW of electricity and have a 6:1 ratio of heat to power output. Any excess electricity can be sold back to the grid. While not considered renewable, micro-CHP can reduce carbon emissions and energy costs when properly installed.
The document discusses micro wind technologies. It explains that micro wind turbines harness wind energy to generate electricity. It describes the basic workings of horizontal and vertical axis wind turbines. The document also outlines planning requirements, regulations, advantages such as feed-in tariffs, and disadvantages like inconsistent power generation from variable wind speeds.
This document discusses biomass as an environmental technology system. It defines biomass as biological material derived from living or recently living organisms, including both plant and animal material. Biomass is a renewable, low-carbon fuel available in the UK that can provide environmental and social benefits if managed sustainably. Properly managed biomass can deliver significant carbon emission reductions compared to fossil fuels. The document also discusses biomass systems, considerations for biomass installations, building regulation requirements, advantages and disadvantages of biomass systems.
A photovoltaic system uses doped silicon semiconductors that generate electricity when exposed to light. N-type silicon has extra electrons added by doping, while P-type silicon has electron deficiencies added by doping. When joined together, the silicon types allow electrons to flow when struck by photons, generating electricity. A feeding tariff is a subsidy for solar power. An installer of a PV system would need qualifications in electrical work and safety procedures.
Solar photovoltaic (PV) systems convert sunlight into electricity and require planning for optimal installation angles and orientation. An inverter in a solar PV system converts the variable direct current (DC) output of the solar panels into alternating current (AC) that can power homes or feed into electrical grids. Solar PV systems provide advantages such as reduced energy costs, reliability, and reduced environmental impact but also have disadvantages including high installation costs, dependence on sunlight, and limited storage capacity.
The document discusses solar photovoltaic (PV) systems, including how PV cells work by converting sunlight into electricity, how solar inverters convert the direct current from PV panels into alternating current, and considerations for installing a solar PV system such as suitable roof orientation and any planning or building regulation requirements. It also outlines advantages such as receiving feed-in tariffs for electricity exported to the grid and reducing carbon emissions, and disadvantages like needing a large unshaded south-facing roof area to maximize returns.
The document discusses air source heat pumps, which absorb heat from outside air to heat buildings. It explains that air source heat pumps extract heat from outside air using a refrigerant cycle, even when temperatures are as low as -15°C. The document also outlines the types of air source heat pump systems, how they work, considerations for installation location and planning, and the advantages and disadvantages of air source heat pumps.
Ground source heat pumps extract heat from the ground through a system of pipes or coils to heat buildings. They work like a refrigerator by using a compressor to move heat from one place to another. The heat pump unit is installed indoors while horizontal coils are buried underground to absorb heat from the ground. Ground source heat pumps have advantages like reduced running costs and emissions but require careful installation to work effectively.
The document discusses solar thermal hot water systems, which use solar panels fitted to roofs or other surfaces to collect sunlight and heat water. It notes the main renewable energy sources for homes include sunlight, heat from the earth/air/water, biomass, waste, hydropower, and wind. Solar thermal systems can reduce energy bills and carbon footprint while providing hot water year-round, though they only work during the day and have high upfront costs. Proper installation requires checking the roof's structural ability to support panels and avoiding shaded areas, with some systems qualifying as permitted development under planning rules.
1. 7 Electrical installation
operations
This chapter covers the learning outcomes for:
Understand and demon
strate fundamental elec
operations trical installation
City & Guilds unit number 106; EAL unit code QACC1/06; ABC unit
code A04 for Level 1 and A02 for Level 2.
In this chapter, you will learn about basic electrical practical applications.
You will gain knowledge of the types of tools, materials and equipment used
within the electrical industry. You will also consider how to use them safely in
accordance with key health and safety legislation.
The electrical industry is a large and diverse sector. It covers domestic,
commercial and industrial installations, from domestic lighting and power
to industrial heating and specialist installations, such as intruder alarms and
CCTV. It also includes electrical repair and maintenance. This means that
different organisations require specialist skills, tools, materials and equipment.
For example, you will require different expertise for domestic lighting compared
to the skills required by an alarm engineer.
In this chapter you will learn about:
■ health and safety when carrying ■ materials and components used
out basic electrical practical within the electrical industry
applications ■ basic electrical practical
■ electrical hand tools and their safe applications.
use and maintenance
2. Access to Building Services Engineering
Introduction to electrical circuits
The two main types of electrical circuit that you need to
understand are:
■ the power circuit – otherwise known as the ring main
or radial
■ the lighting circuit.
Power circuits
Key terms
This type of circuit feeds a 13 A (ampere or amp)
Junction box: socket. The ring main flows in two directions to reach
Contains terminals the socket, as shown in Fig. 7.1. Junction boxes can be
for joining electrical
used to extend the circuit.
cables.
Line (hot/phase/live)
T O O L B OX TA L K Neutral
Earth (ground)
Part P of the
Building Regulations
states that only a
competent person
is allowed to carry
out installation and Junction box
modification of Consumer unit
electrical wiring.
Fig. 7.1 A ring main circuit with a junction box spur and a
spur from a socket
The consumer unit will have devices, such as fuses,
Key terms
that control and protect the circuit. Both the power
PVC: Polyvinyl chloride. and lighting circuits use PVC-insulated cable and are
supplied by the consumer unit.
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3. Electrical installation operations
Lighting circuits
A lighting circuit is protected by a 5 A or 6 A protective
device in the consumer unit. The cable is routed from
the consumer unit through a number of ceiling roses or
wall light fittings. Each of these is, in turn, connected via
a light switch.
Junction box
Consumer unit
Fig. 7.2 A simple lighting circuit
Health and safety when carrying out
basic electrical practical applications
Personal protective equipment
When you work with electrical applications, it is essential
that you wear the correct personal protective equipment
(PPE). For example, you will need to ensure that you
have adequate protection for your:
■ eyes (e.g. safety goggles)
■ hands (e.g. gloves)
■ head (e.g. a hard hat)
■ clothing (e.g. overalls)
■ feet (e.g. steel-capped boots with rubber soles).
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4. Access to Building Services Engineering
Turn back to Chapter 2, pages 34–6, to remind yourself
of the different types of PPE and their uses.
Identify and report any potential workshop hazards
Key terms
When carrying out a risk assessment, you need to:
Risk: The chance, ■ state the task
high or low, that
somebody will be ■ identify any hazards associated with that task
harmed by a hazard. ■ name any people who could be affected by those
Hazard: Anything hazards
that could cause
harm. ■ account for any existing control measures
■ evaluate the risks by considering both the likelihood
of the identified hazards causing injury and the
possible severity of such injuries
T O O L B OX TA L K
■ decide upon any further actions required to reduce
the risks, and prioritise those actions.
You need to review
your risk assessment
Demonstrate how to reduce the risks for workshop
annually, or when
making changes in activities
the workplace, such To control any risk of an accident occurring in the
as new machinery, workplace, you need to consider the following risk controls.
substances,
procedures or These can be summarised using the acronym ERIC.PD:
employees, or if
there is an accident
■ Elimination – it might be possible after a risk
or near miss. assessment to completely remove the hazard and,
therefore, any danger associated with it.
■ Replacing or substitution – this means replacing items
or equipment with safer alternatives. For example,
using an electric screwdriver insulated to 1000 V in
place of a standard screwdriver will help prevent
electric shock when working on installations.
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5. Electrical installation operations
■ Isolation or enclosure – this is also known as Did you know
encircling. For example, it could be restricting access
to electrical panels or using barriers to prevent entry In 2009–2010:
to working areas. 147 workers were
killed at work.
■ Control – this means controlling the working 121,430 other
environment by ensuring protective measures injuries to employees
and safe systems of work, and informing others were reported.
1.3 million people
of these. One example is a permit to work on live who worked during
electrical circuits that includes a safe isolation the previous year
procedure. were suffering from
a work-related
■ PPE– always use the correct PPE for the work activity. illness.
■ Development – this refers to the need for proper (Source: www.hse.
gov.uk/statistics/
supervision and the provision of information and index.htm)
training regarding the workplace and the hazards
involved.
activity
Consider what you learnt about health and safety in
Chapter 2.
Then identify any hazards in your working
environment, for example, chemicals, asbestos,
electricity, tools and ladders.
Now assess the risks arising from these hazards.
You need to consider all people in the workplace,
whether young or old, people with disabilities,
apprentices, trainees or visitors.
When evaluating the risks, you need to take into
account any existing control measures, such as
machine guards or competent persons who are
trained in the work activity.
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6. Access to Building Services Engineering
Electrical hand tools
and their safe use and
maintenance
There are two basic categories of hand tool:
■ General engineering, construction work, repair and
maintenance hand tools
■ Electricians hand tools.
Electricians need specialist tools and equipment due
to the nature of their working environment and the
dangers associated with electricity.
One of the key differences with tools used by electricians
is that they are insulated to provide protection from
electric shock. Electricians’ tools are insulated to 1000 V,
which is classed as low voltage in the BS 7671 IET
REMEMBER
Wiring Regulations (17th Edition, 2011).
Only use tools insulated
to 1000 V when Electric shock occurs when a person becomes part of the
working on electrical
installations. circuit. The severity of shock will depend on the level of
current and the length of time it is in contact with the body,
but the lethal level is usually 100–200 mA (0.1–0.2 A). At
this level of current, the heart fibrillates and breathing stops.
T O O L B OX TA L K
Screwdrivers
There are various types of screwdrivers, for example:
Do not use electrical
screwdrivers on live ■ a slotted flat tip (engineer’s screwdriver) is used for
equipment if there is
installing accessories and general use
any damage to the
tip or insulation. ■ crosshead screwdrivers (Phillips and Pozidriv) give
better torque when used with crosshead screws,
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7. Electrical installation operations
which are often used to secure accessories and Key terms
terminals in miniature circuit breakers
■ electrical screwdrivers are designed and certified by VDE: Verband der
Elektrotechnik, the
VDE for use around live equipment up to 10,000 V. Association for
They are available in slotted or crosshead. Electrical, Electronic
and Information
When using a screwdriver: Technologies.
■ always make sure that the tip fits snugly into the
head of the screw as this will prevent damage to the
screwdriver
T O O L B OX TA L K
■ check that it is dry after use, as moisture left on the
screwdriver will cause it to rust and corrode
Flat tip screwdrivers
■ replace it if it is damaged, as using it may cause you should never be
to slip and harm yourself or damage the work used on crosshead
screws, or as a
■ only use it for the job it is designed for – screwdrivers centre punch or
are NOT designed for prising open paint cans, scribe to make holes
chiselling brickwork, hammering, door wedges and for screws.
lifters, prying or lifting boards.
Pliers and cutters
■ Side cutters – a key tool for all electricians, they are
used every day to cut and prepare wire for connection.
Side cutters should not be Trade tip
used to cut cable wider
Side cutters and
than 2.5 mm2 as this
pliers should
will damage the cutting be kept dry and
blades. lubricated as per
Fig. 7.3 Insulated side cutter the manufacturer’s
■ Combination pliers – as instructions.
their name implies, they
have a combination of features designed to make
them versatile. The flat serrated jaw is used to twist
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8. Access to Building Services Engineering
together stranded copper wire before making a
connection. The curved serrated jaw is designed for
gripping round metal rod or tube. It can also be used
for holding screwheads or nuts.
■ Long nose pliers – these are simply a type of
combination pliers specially adapted for working in
Fig. 7.4 Pliers confined spaces, for example, when placing small
washers or nuts on to fittings, and assembling wiring
in tight spots.
■ Pliers wrench – this is ideal for gripping flat surfaces,
such as nuts, without damaging the surface. The jaw
can be adjusted to suit the size of the conduit or nuts.
■ Insulation strippers – these are used to remove the
insulation from around the conductor. Care needs to
be taken and the wire strippers set to the correct cutting
depth so as not to damage the copper conductor. (Any
damage will reduce the current-carrying capacity and
size of the conductor.)
Fig. 7.5 Insulation strippers
■ Crimping tools – electrical cables are often
terminated using metal lugs that are fitted to the
conductor either by soldering or crimping. Part of the
lug is squeezed securely on to the conductor using a
crimping tool.
Trade tip
Fig. 7.6 Crimping tool and Never leave tools wet – always dry them and use
crimps a recommended lubricant to protect from rust.
Never drop tools into your toolbox.
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9. Electrical installation operations
Measuring equipment
As an electrician, you will need to use a range of
measuring equipment in order to ensure that cables and
support systems are installed level and at the correct
distances (i.e. in line with drawings and diagrams). The
measuring tools you use will range from simple rulers to
laser levelling equipment. However, you need to take care
to ensure that all measuring equipment does not get wet
or dropped, as this will cause inaccurate readings.
■ Steel rulers – used for general measurements of
trunking or tray.
■ Steel tape measures – used for longer Fig. 7.7 Laser and tape
measurements, for example, trunking and conduit measure
lengths or the area of a room.
■ Spirit levels – used to check both vertical and
horizontal alignment.
■ Laser measuring tools – used to measure long
distances, for example, one end of a large
Fig. 7.8 Spirit level
warehouse to the other end.
■ Plumb bobs and chalk lines – used to install and align
equipment and accessories vertically. They are weights
on the end of a string – when the weight stops moving,
the string is at true vertical.
Power tools REMEMBER
If electrical equipment
Before using any power tools, you will need to carry is operated at 230 V
out the portable appliance testing (PAT) pre-use checks or higher, it should be
described in Chapter 2, page 49. protected by an RCD
(residual current device).
■ On a construction site, electrical tools usually operate
at 110 V to reduce the risk of electric shock.
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10. Access to Building Services Engineering
■ Portable electric tools should only be used for their
designed purpose.
■ Never use worn, blunt or damaged bits or other
accessories.
■ Use battery-operated drills and saws where possible,
to prevent electric shock.
Multimeters and test instruments
All test instruments and test leads must comply with the
relevant regulations. The HSE has published guidance
notes, called GS38, Electrical Test Equipment For Use
by Electricians. The BS 7671 IET Wiring Regulations
specifies the test voltage and current required to carry
out a particular test.
GS38 states that:
■ all probes should have finger barriers
■ the probe tips should be insulated, to prevent more
than 2 mm showing, or spring-loaded retractable
screened probes used
■ probes should be protected by a 500 mA high
breaking capacity (HBC) fuse
Did you know ■ leads should be adequately insulated, of
distinguishable colours, flexible and of sufficient
The symbol for length.
alternating current
(AC) is: Test equipment should be regularly checked and
calibrated. Before use, ensure that:
The symbol for direct
current (DC) is:
■ batteries are in good condition
■ there is no damage to the casing
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11. Electrical installation operations
■ test leads and probes are undamaged and conform
to GS38 (see page 182)
■ the calibration certificate is valid and current.
Digital multimeters
Digital multimeters are designed to measure alternating
current (AC) and direct current (DC).
■ AC is generated at 25 kV and stepped down to 230 V
for domestic properties using a transformer.
■ DC voltage uses battery or photovoltaic (solar) panels.
The meters will measure voltage, current and resistance
at different values from millivolts and milliamperes (or
milliamps) to kilovolts and kiloamperes (or kiloamps).
■ When measuring voltage, the multimeter must be
connected in parallel across the load or across the
supply, from positive to negative (see Fig. 7.10). Fig. 7.9 A digital multimeter
■ To measure current in a circuit, the multimeter is
connected in series, as shown in Fig. 7.11.
■ To measure ohms using a multimeter, you need to set
it to Ω and then decide on the value you want – low
ohms (mΩ) or high ohms (kΩ).
V
A
V A Ω
V A Ω
Supply Load
Supply Load
Fig. 7.10 Measuring voltage in parallel Fig. 7.11 Measuring current in series
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12. Access to Building Services Engineering
REMEMBER HAVE A Go...
Voltage (V) is measured
Make up a circuit using a 2.4 V krypton (cycle)
in volts (V).
Current (I) is measured light bulb, a lamp holder, a 9 V battery, a switch to
in amperes (A). control the circuit, and 1 mm2 conductors or similar.
Resistance (R) is
measured in ohms (Ω). Then measure the voltage and current.
Next, measure resistance in ohms (Ω) in the circuit
at various points. To do this, measure each length of
conductor. Check for breaks in the conductors and
Trade tip the resistance across the lamp (this is checking the
continuity of the conductors). Remember to attach
When terminating
the positive test probe to the positive terminal and
cables, it is good
practice to double the negative probe to the negative terminal.
over the end of the
conductor. (There You can now calculate your answers to check
should be no against your readings using Ohm’s law (V = I × R
exposed copper at or I = V/R or R = V/I).
the terminals.)
If you measure the current and the voltage, you will
get: R = 9 V ÷ 0.7 A = 12.86 Ω
Materials and
components used within
the electrical industry
Cables
Cables conduct electricity in circuits and usually consist
of a conductor, such as copper or aluminium.
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13. Electrical installation operations
PVC-insulated and sheathed flat wiring cables
This type of cable (manufacturers’ reference code 6242)
is commonly used for domestic and commercial wiring
circuits. It can be sunk into walls and installed in conduit
or trunking. It can also be surface-mounted when there
is little risk of mechanical damage.
The conductors within PVC-insulated cable have a
colour-coded insulator (brown = live and blue = neutral)
and a bare copper conductor that is sheathed green
and yellow to indicate the circuit protective conductor
(earth cable). They are sheathed mechanically, and the
sheathing is usually grey or white PVC.
Single PVC unsheathed cables are used in conduit
and trunking installations (see page 188). PVC cable
is flexible and the least expensive type. It must not be
installed below 0 °C or above 60 °C. The conductors can
be solid or stranded.
PVC cables are fixed vertically or horizontally with
Fig. 7.12 Twin and earth in
plastic cable clips, using a cross pein hammer. (The new colours, including earth
requirements for bends and support can be found in sheathing
Tables 4A to 4E in the IET On-Site Guide).
To terminate PVC/PVC cable you need to follow these
steps:
1. Nick the end of the cable with an electrician’s knife
and pull it apart.
2. When the required length has being stripped, cut off
the surplus sheathing with the electrician’s knife.
3. To remove the insulation from the conductors, use
the wire strippers. Check that the conductors are not
damaged and double the ends over with your pliers. Fig. 7.13 Cable clips
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14. Access to Building Services Engineering
■ Stranded conductors should have the strands twisted
together to provide a better connection – there
should be no bare copper and no loose strands that
protrude out of the terminal.
PVC-insulated and sheathed flexible cables
This type of cable falls under manufacturers’ reference
codes 3092Y and 3093Y.
The construction of the flexible cord is made up of
stranded copper conductors insulated in heat-resistant
PVC. It is suitable for installations up to 85 °C, so must
not be used on heating appliances.
General purpose flexible cord
These types of cord (manufacturers’ reference codes
3182Y and 3183Y) are available in:
T O O L B OX TA L K
■ twin core (brown, blue) used on Class 2 appliances
It is important to ■ three core, where an earth is required (brown, blue,
check that all cables green/yellow)
conform to British
Approvals Service
■ four core (black, grey, brown, green/yellow)
for Cables (BASEC). ■ five core (black, grey, brown, blue, green/yellow).
This cable is used to connect domestic appliances to
13 A plug tops and is used for light pendants.
Flexible cable does not require earth sheathing as there
are no bare copper conductors.
Wiring systems
There are many different types of wiring systems,
enclosures and equipment. They all have to conform
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15. Electrical installation operations
to the current BS 7671 IET Wiring Regulations. The
regulations require that all electrical installations are
designed to provide:
■ protection of persons, livestock and property
■ the proper functioning of the electrical installation for
the intended use.
This type of work is carried out by the designer at the
planning stage.
PVC-insulated and sheathed wiring systems
These are used extensively for lighting and power
installations in domestic dwellings. To minimise
mechanical damage to the cable caused by impact or
penetration, the cables:
■ must be installed into walls 50 mm below the surface
or protected against damage by screws or nails using
earthed metal conduit
■ must be run within 150 mm of the top of a wall
or within 150 mm of the corner and must run
horizontally or vertically to the item of equipment.
In addition:
■ when installed under floors and above ceilings,
cables must be at least 50 mm below the surface or
protected against mechanical damage
■ when installing into metal back boxes, grommets
must be fitted and all sharp edges removed from any
accessories used
■ cables should not cross over each other or come into
contact with gas or water pipes or other non-earthed
metal work.
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16. Access to Building Services Engineering
Conduit
Earth or circuit protective conductor
Load The earth wire is the circuit protective conductor (CPC)
and is there to protect you, the equipment and the cable
Earth from a fault in the circuit.
You must make sure that the earth connection is continuous
Line Supply Neutral
all the way through the circuit from the supply to the load.
Fig. 7.14 Load supply and
earth
Steel conduit
The three main types of steel conduit that are commonly
used are:
■ black enamel conduit, which is used where there is
no likelihood of dampness
■ stainless steel, which is used in catering environments
■ galvanised conduit, which is used outdoors.
PVC non-sheathed cables are run inside the steel
conduit, which provides excellent mechanical protection
and, in certain conditions, may also provide the means
of earth continuity.
The steel conduit is screwed into accessories using
special tools called stock and die. These are used to put
Trade tip
a thread on to the end of the steel conduit, so that the
When installing
conduit can be bent to form right-angle bends and sets.
conduit or trunking, The bends are then put into the steel conduit using a
remove all burrs and bending machine.
sharp edges using a
conduit reamer or a Conduit should have a minimum bending radius of 2.5
file. This will avoid times the diameter. The amount of PVC non-sheathed
damage to the PVC
non-sheathed cables.
cable installed in conduit or trunking should not exceed
45% of the internal cross-sectional area (CSA).
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17. Electrical installation operations
Both PVC and steel conduit come in lengths of 3.75 m.
Typical diameters are 16 mm, 20 mm, 25 mm and 32 mm.
The types of fittings used are spacer bar saddles,
distance saddles, hospital saddles and grampets. A
terminal end box is used to attach lamp holders, and
through boxes and tee boxes are used to add vertical or
horizontal drops to the installation.
PVC conduit
There are two types of PVC conduit: flexible and rigid. Fig. 7.15 Bending
machinery and fittings
Expansion couplers need to be fitted to rigid PVC
conduit, to allow for expansion of the conduit.
■ PVC glue should be used with care to join the
accessories together.
■ PVC conduit can be cut with a junior hacksaw.
■ To put different bends into the PVC conduit, heat is
applied to the area and a coiled spring inserted; the
bend is then formed using the knee or thigh.
Trunking
Trunking is available in 3 m lengths and a range of
CSAs. There are many types of trunking available, for
example:
■ busbar and rising mains is used for special installations
■ special trunking is used for skirting, dado and floor
trunking
■ PVC mini trunking is often used in domestic dwellings
for surface wiring – it can be bought with a self-
adhesive backing
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18. Access to Building Services Engineering
■ steel trunking is used for commercial and industrial
T O O L B OX TA L K purposes – it is fixed using roundhead screws and
raw plugs.
Fire barriers must The same fittings are used for both PVC and steel
be fitted inside the trunking. You can buy bends and adaptors for trunking
trunking every 5 m,
ready formed.
on every floor level
or room and any To cut trunking, you need to use a hacksaw; burrs and
dividing wall.
sharp edges are removed using a file. When joining two
lengths of steel trunking together, copper earth straps
are used to provide an earth path.
Conduit is often used with trunking as a combined
system.
Types of circuits and accessories used
with PVC-insulated cables
REMEMBER
Within domestic dwellings, there are three common
All switches and sockets
must be installed at types of lighting circuits and two different power circuit
a height of between arrangements. These are:
450 mm and 1200 mm
■ lighting circuits – one-way; two-way; intermediate
■ power circuits – radial; ring main.
Radial circuits
Line (hot/phase/live) Radial circuits use twin or single sockets. They do not
Neutral
Earth (ground) loop back to the consumer unit; they end at the last
socket.
■ A2 radial circuits are wired in 4 mm2 PVC/PVC and
Consumer unit protected with a 30/32 A MCB, cartridge fuse, RCD
Fig. 7.16 Radial circuit or RCBO. The floor area must not exceed 75 m2.
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19. Electrical installation operations
■ A3 radial circuits are wired in 2.5 mm2 and protected
by a 20 A protective device. The floor area must not
exceed 50 m2.
Ring main circuits
Ring main circuits start and finish at the consumer unit
(line, neutral and CPC). They are connected to each
socket in turn, and return from the last socket to the
correct terminals in the consumer unit. (Single or twin
sockets are classed as one outlet.)
Line (hot/phase/live)
Neutral
Earth (ground)
Non-fused REMEMBER
socket
When installing PVC
cables, use grommets
with metal boxes and
remove all sharp edges
from PVC back boxes.
Consumer unit
Fig. 7.17 Ring circuit with a spur
Ring main circuits are connected in 2.5 mm2 PVC/PVC. Trade tip
A 30/32 A protective device is used. The floor area must
not exceed 100 m2. An unlimited number of sockets can Remember to check
that all terminals
be installed, provided the regulations are adhered to. are secure, by
gently tugging the
conductor, before
Non-fused spurs attaching sockets to
These are limited to the number of sockets or items of the back boxes.
fixed equipment on the ring and they must use the same
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size cable. So, for example, in Fig. 7.17, you could have
three non-fused spurs, single or twin sockets or a fixed
item of equipment.
Spurs are connected to the ring directly from the
consumer unit by the use of a junction box or from a
Fig. 7.18 Double-switched
socket (see Fig. 7.17).
socket
The circuits are constructed using switched socket outlets
(single and double) or non-switched sockets, which
prevent a circuit being turned off accidently. The sockets
can be metal clad or PVC and are attached to metal or
plastic back boxes.
Fig. 7.19 The reverse side
of a single-switched socket Lighting circuits
Lighting circuits are connected using metal or PVC light
switch plates and back boxes. They are used for ceiling
roses and lamp holders.
One-way circuit
The most basic lighting circuit is the one-way circuit.
A circuit’s name depends on the switching arrangement
– the one-way switch controls the lamps from one
Fig. 7.20 Ceiling pendant position (see Fig. 7.22). In this case, the switch feed is
lamp holder connected from the fuse to the common (C) in the switch
and the switch wire is connected between the L1 switch
terminal and the lighting point. The neutral is connected
directly to the lighting point.
To connect two lamps, the supply is connected to the
switch and a neutral is connected to the lamps. It is a
common neutral.
Fig. 7.21 Light switch
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21. Electrical installation operations
■ The switch wire feeds both lamps and they will come Loop-in
Switch feed
on together. Neutral Switch wire
■ The two lamps are connected in parallel, so that the
supply voltage appears across each lamp. Fixing holes
Support for flex
Switch feed One-way switch
Feed from
Switch wire the supply
Line
C L1
Common
CPC Light point
Neutral L1
Fig. 7.22 One-way lighting circuit diagram Fig. 7.23 Connections for
the loop in method at ceiling
rose (not showing the light
Consumer unit fitting connections) and one-
way switch
Neutral Earth Neutral
ON ON ON
TEST TEST
OFF OFF
6A 32A 32A 32A RCD 6A 45A RCD OFF
Fig. 7.24 A consumer unit
REMEMBER
When using metal
This should be a 17th edition consumer unit housing accessories, ensure all
exposed conductive
45 A, 32 A and 6 A MCBs to BS EN 60898. It should parts are earthed.
also include additional protection by means of 80 A and
63 A / 30 mA RCD, with a 100 A double pole isolator.
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The 45 A is used to protect the shower circuit, the
three 32 A are for the kitchen, upstairs and downstairs
sockets, and the two 6 A are used for upstairs and
downstairs lighting circuits.
Protective devices
Residual current device (RCD)
T O O L B OX TA L K An RCD monitors the current in the line and neutral
conductors on a continuous basis. It operates when
there is an earth fault; in a healthy circuit, both currents
RCD functional
testing should be will be equal. When a fault occurs, some current will
carried out quarterly flow to earth and the line and neutral currents will
by pressing the test become unbalanced. The RCD will detect the imbalance
button.
and disconnect the circuit.
Residual current circuit breaker with overload
protection (RCBO)
RCBOs are a combination of an MCB and an RCD.
They offer protection against earth leakage, overload
and short circuit currents.
An overload of the circuit occurs when too much power
Fig. 7.25 25 A 30 mA RCD is drawn from a healthy circuit, for example when
extra load is added to an existing circuit or too many
adaptors are used in socket outlets, exceeding the rated
load current.
A short circuit occurs when there is a severing of live
conductors and insulation breakdown.
Examples of an earth fault include insulation
breakdown, incorrect polarity and poor terminations.
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23. Electrical installation operations
Plug tops
REMEMBER
13 A plug tops use BS EN 1362 fuses to protect the
A fuse protects the
appliance flexible cord. They have three pins. The earth cables from damage. BS
pin is connected to the circuit protective conductor (CPC) 7671 Regulation 43-02-
of the ring or radial circuit and is longer so that it is the 01 states that current
rating (In) must be no
last electrical connection to be removed from the circuit. less than the design
The other two partially insulated pins are connected to current (Ib) of the circuit.
the line (brown cable), which is connected to the fuse,
and the neutral (blue cable).
HAVE A Go...
Terminating flexible cable into accessories
Using a BS 1363 plug top, terminate a three-core
flexible cord.
You will need to:
1. use the stripping knife and lightly score around
the flex’s outer sheathing
2. bend the flex where you have scored it (this
should part the outer sheathing)
3. pull the outer sheathing off (you should not be able
to see any copper where you have used the knife)
Fig. 7.26 13 A plug top
4. use the wire strippers to strip back the ends of with conductor lengths
the wire around 10 mm to reveal the copper
(make sure the strippers are set to the correct
cutting depth)
5. twist the stranded copper conductors tightly and
insert into the correct terminals (brown = line; REMEMBER
blue = neutral; green/yellow = CPC). Always use the cable
grips in plug tops and
Note: the earth wire in a flexible cable already has ceiling roses.
sheathing fitted.
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24. Access to Building Services Engineering
HAVE A Go... Working out the correct fuse required
It is important to check that you are using the correct BS
Select an electrical 1362 fuse. This should be either a 3 A red up to 700 W,
piece of equipment a 5 A black up to 1000 W (1 kW) or a 13 A brown up to
and look at its power 3000 W (3 kW).
rating. Calculate the
fuse required. Power (P) in a circuit is found using the formula
P = I × V. As you want to find current (I), you need to
transpose the formula to I = P/V.
For example, for a 1300 W drill supplied by 110 V: I =
1300 W/110 V = 11.82 A
You would therefore use a BS 1362 13 A cartridge fuse.
Basic electrical practical
applications
Common types of fixings
Within the electrical industry, a large variety of fixings are
used. These range from girder clamps used on RSJs to
raw bolts used to secure equipment to walls and floors.
The various types of fixings and their uses include:
■ wood screws and plasterboard fixings, fast fix, spring
toggles and gravity toggles are used on cavity walls
■ masonry nails are used with PVC clips
■ galvanised clout nails are used for fixing capping
onto masonry walls
■ pop rivets are used to install two pieces of metal together
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25. Electrical installation operations
■ different types of threaded metal bar and wire cables
are used to support or suspend cable systems (basket
tray or lighting trunking)
■ wood screws are used to secure equipment to wood
or, when used with plastic raw plugs, to fix equipment
to masonry.
Different types of raw plugs have different types of heads. Fig. 7.27 Different types of
Those with round heads are used for trunking, while raw plugs
those with counter sunk heads are used for spacer bar
saddles or when accessories have counter sunk recess.
Screws are selected by the shank diameter, length, type
of head (cross, slotted) and the metal finish used for the
type of environment, for example, non-ferrous is coated
with rust prevention.
Cable clips are used to secure PVC cable to walls. It is
good practice to place the nail part underneath the cable
when installing horizontally, to give additional support.
Diagrams and drawings
There are many different types of electrical drawings
and diagrams, for example, circuit, schematic wiring,
layout, and block diagrams.
Block diagrams
This is the simplest type of diagram. Squares or
rectangles are used to represent pieces of equipment. Service Energy Consumer
cut out meter control
Block diagrams show how the components of the circuit
relate to each other, but do not show details of termination. Fig. 7.28 Block diagram
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26. Access to Building Services Engineering
Circuit diagrams
Circuit diagrams are very similar to schematic diagrams
and use BS EN 60617 symbols. They show how the
circuit is connected but not the physical connections.
Did you know N L1 L2 L3
A common ratio for
drawings is 1 : 50. So
10 mm on a drawing
using this ratio would
represent 500 mm in
real life.
Fig. 7.29 Three-phase motor circuit diagram
Schematic wiring diagrams
These show how the circuit is wired. They include a
physical layout of the cable route and the accessories.
HAVE A Go...
1. Produce a circuit
Loop
and wiring Neutral Line
diagram for a
Line
two-way one-light Neutral
circuit.
Common
2. Using BS EN
symbols, produce ON
TEST
a layout diagram OFF
RCD 6A
L1
for a room in
your house.
Fig. 7.30 One-way wiring diagram. (This shows a simplified
consumer unit for clarity)
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27. Electrical installation operations
Layout diagrams
One-way
switch
Layout diagrams use BS EN 60617 symbols and are
scaled drawings (common scales are 1 : 50 and 1 : 100).
Safe isolation procedure
Before testing a circuit, you need to ensure that the Fluorescent lamps
circuit is dead and isolated from the supply. Consumer
unit
1. Locate and identify the circuit or equipment to be
isolated and the means of isolation (this could be the
fuse or isolation switches).
2. Lock off the electrical supply and place a warning Fig. 7.31 Layout diagram
sign (e.g. ‘Safety electrician at work’). with six fluorescent lamps, a
consumer unit and a one-
3. Select an approved voltage indicator or test lamp.
way switch
4. Check that the device is functioning correctly on a
known supply or a proving unit.
5. Check the circuit or equipment to be worked on is
dead using the approved voltage indicator or test
lamp. (Test line to earth, line to neutral, neutral to
earth.)
6. Recheck the approved voltage indicator or test lamp
on a known supply or proving unit. Fig. 7.32 Kit for safe
isolation
Continuity of the CPCs test
REMEMBER
Two tests are used to check that the conductors are SOLO (Switch Off, Lock
electrically sound and correctly connected. Off).
Always carry out safe
isolation before starting
Link method work.
1. Link the line conductor and the protective conductor
together at the consumer unit.
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28. Access to Building Services Engineering
2. Use the low ohmmeter to test between the line and
earth terminals at all light switches, light fittings and
equipment.
3. Record the highest value of R1 and R2 on the
installation schedule.
4. Use the value of R1 and R2 to calculate the earth fault
loop impedance.
Ω
V A Ω
Line Neutral CPC
Temporary link
Fig. 7.33 Link method of testing
Long lead method
This method is used to obtain continuity of the bonding
Trade tip
conductors.
When using both 1. Connect one lead to the consumers’ main earth
test methods to
check continuity terminals, and the other lead to a trailing lead.
of the CPC, it is 2. Test the protective conductors at light switches and
important to remove
light fittings.
supplementary
bonding to prevent 3. Record the highest value of R2 on the installation
false readings from schedule.
parallel paths.
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29. Electrical installation operations
Ω
V A Ω
Line Neutral CPC
Fig. 7.34 Long lead method of testing (also check earth in switch)
Continuity of ring final circuit conductors test
The continuity of each conductor, including the CPC of
every ring final circuit, must be checked to ensure that
the ring is complete, has no interconnections and is not
broken. The test is carried out in three steps.
1. Test the line, neutral and CPCs end to end at the
consumer unit. Assume R1 is the line, R2 is the earth,
and Rn is the neutral. If wired in PVC/PVC twin and
earth, the reading for the earth conductor should be
1.67 times greater than R1 (within 0.05 Ω), when the
same size conductors are used.
Neutral Earth Neutral
Ω
ON ON ON V A
TEST TEST
OFF OFF
6A 32A 32A 32A RCD 6A 45A RCD OFF
Fig. 7.35 Continuity of ring testing step 1
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30. Access to Building Services Engineering
2. Connect the line and neutral conductors together
L1 N1 L2 N2
so that the outgoing line (L1) is connected with the
returning neutral (N2) and the outgoing neutral (N1)
is connected to the returning line (L2). Measure the
resistance of the line and neutral conductors at each
Fig. 7.36 Continuity of ring socket outlet. The readings obtained should be mostly
testing step 2 the same; the measured value would be a quarter of
(R1 + Rn) if readings are obtained in step 1.
L1 E1 L2 E2 3. Repeat the previous steps with the line and CPC
cross connected at the consumer unit and test each
socket. Record the highest resistance value of R1 +
R2 on the installation schedule. This test also confirms
polarity of each socket outlet and can be used to
Fig. 7.37 Continuity of ring
determine the earth loop impedance value of the
testing step 3
circuit. The measured value at each socket outlet
and at the consumer should be mostly the same;
the measurement would be a quarter of (R1 + R2 ) if
readings are obtained in step 1.
Completing the task
It is important that you ensure that the work area is left
in a safe condition after the task. You will need to make
sure that you:
■ leave the area clean and tidy
■ return tools and equipment to their proper place
■ return excess materials
■ dispose of any waste materials in accordance with
the Waste Electrical and Electronic Equipment (WEEE)
Regulations (2006).
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31. Electrical installation operations
check your knowledge
Level 1
1. What tool would you use to remove insulation from a conductor?
2. Name three checks to be carried out on test equipment before use.
3. What is measured in parallel and what is measured in series?
4. What is measured in ohms? Draw the ohms symbol.
5. At what height should sockets and switches be installed in domestic
properties?
6. A ring main wired in 2.5 mm2 and 1.5 mm2 PVC/PVC should have what size
of protective device?
7. Explain why lighting circuits are connected in parallel.
8. Explain why the earth pin of a 13 A plug top is longer than the line and
neutral.
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