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  • Trainer's Notes:
    Duration: One Hour
    Demonstration Materials:
    Extension cords (good, defective, household use only)
    GFCI example types (receptacle, breaker, portable)
    3. Short piece of 12-2 wire.
    4. Jury-rigged items as may be available as bad examples.
  • Trainer's Notes:
    This training module is not designed to teach you to work as a qualified electrician.
    It is designed to help you recognize and avoid some of the Focus Four electrical hazards associated with masonry work.
    If you spot problems on your job site, notify your supervisor.
  • Trainer's Notes:
    The law requires your employer to follow these standards.Your employer also must ensure that you and you co-workers follow the safe work practices within the electrical standard.
    OSHA standards are considered the bare minimum needed to protect the worker.
    NEC requirements that directly affect employees in construction workplaces have been placed in the text of the OSHA standard.
  • Trainer's Notes:
    Stress the importance of electrical safety.
    Remind them not to underestimate the hazards associated with electricity. We sometimes become complacent about electrical hazards because we cannot hear, smell, or see electricity.
    Ask participants if they have ever experienced an electrical shock.
  • Trainer's Notes:
    Leading causes are usually viewed as “symptoms” to a deeper problem.
    Often management and leadership problems (root causes) allow the leading causes to exist or form.
    Ask the participants to name some root causes which might allow some of these leading causes to exist.
  • Trainer's Notes:
    Ask the participants the difference between a shock and electrocution. (Electrocution means DEATH. )
    Explain that shocks lead to other, secondary injuries such as falls due to the worker’s reaction.
    Ask the participants for examples of how each of the accidents might occur.
    Explain NFPA 70E which requires workers to stay at least 4 feet away from any exposed electrical devices
    such as open disconnects and electrical panels with missing covers
  • Trainer's Notes:
    Explain that most workers are exposed to 120 volts.
    Explain that even with a constant 120 volts, the electric flow rate (Amperage) through the body will vary depending on how much Resistance it encounters.
    Explain that the path through your body, your clothing, and whether or not your skin is wet will determine the resistance.
    Amperage through you = Voltage divided by Resistance
  • Trainer's Notes:
    Remind them that metals conduct electricity.
    Explain that some metals, such as copper, are excellent conductors and are used as wire.
    Explain that the human body will conduct electricity.
    Explain that things like rubber, plastic, glass and ceramic are insulators. Further explain the sentence ‘Explain that things like
    rubber, plastic, glass and ceramic are insulators.’ These materials are especially made to be insulators. For
    example, rubber tires for vehicles are not insulators because of the steel belts and carbon black added to
    color the tire black.
  • Trainer's Notes:
    Explain that when a circuit works right, current flows through the HOT wire to the tool. It returns to the source through the NEUTRAL wire.
    Explain that when something goes wrong with a circuit, it is called an electrical fault.
    Explain that when things are right the GROUND has no current flow. A low resistance ground can
    help protect the workers from an electrical injury. If there is a short in a piece of electrical equipment, the
    current will take the path of least resistance. If the worker has a higher resistance than the ground, then the
    current will flow through the ground.
  • Trainer's Notes:
    Explain that the worst part of the body for current to pass through is the chest cavity. Question: WHY?
    ANS. Current directly through the heart is most likely to cause heart fibrillation, that is, interruption of the tiny electrical current that determines the heart’s correct rhythm.
    Technically, the heart’s electrical current is 2-3 micro-amps, or .000002-.000003 amps. Compare that to 20.0 amps in a regular 120 volt circuit – 1.0 amp = 1,000 milliamp = 1,000,000 micro-amp.
  • Trainer's Notes:
    Use the12/2 wire with some of the outside sheathing removed for a visual aid.
    Demonstrate the possible scenarios.
  • Trainer's Notes:
    Ask to see a show of hands of those that have been shocked.
    Remind them that the shock that startled them could very easily have been fatal under different circumstances.
    Explain that there are too many variables to not take electricity seriously.
  • Trainer's Notes:
    Ask the participants to read the incident.
    Ask them if they ever pushed against a drill with their chest.
    Ask them for suggestions on what could have prevented this incident.
  • Trainer's Notes:
    Explain that when it comes to electricity and the human body’s inability to deal with it, we can no longer talk in terms of Amps and must use smaller units.
    Explain that 1 Amp is equal to 1000 milliamps.
    Explain that 1/20 of an amp (50 ma) going through the chest cavity can stop the heart and be fatal.
    Ask them when the typical circuit breaker will trip ?
  • Trainer's Notes:
    Point out the vast difference between wet skin resistance and dry skin resistance.
    Remind the participants that often this alone can be the difference between a shock and an electrocution.
    Also point out using this graphic OSHA’s requirement for guarding of live parts relates directly to the point at which (with reduced resistance) current becomes sufficient to cause an electrocution.
  • Trainer's Notes:
  • Trainer's Notes:
    Explain that at a minimum, employers must follow the OSHA Electrical Standards.
    Explain that these standards provide protection for using temporary wiring in construction.
    Explain that all four proactive methods must be implemented for a safe site.
    Installation
    Guarding live Parts
    Approval for use
    Protection from damage
    Electrical safe practices
  • Trainer's Notes:
    Remind the participants that the whole purpose of electrical isolation is to prevent worker contact with electricity.
    Covers shall be installed on all electrical devices, such as panels, disconnects, motor terminal boxes.
  • Trainer's Notes:
    Explain that an insulator is any material with a high resistance to electric current.
    Stress the importance of ensuring that the tools and equipment they use is free from insulation related defects.
    Ask participants: How does insulation get damaged?
  • Trainer's Notes:
    1926.405(g)(2)(iii) Splices (repaired)
    1926.404(f)(6) Path to ground shall be continuous
    1926.416(e)(1) and (2) Frayed and damaged extension
    cords
    1926.405(g)(2)(iv) Strain relief (explain the hazard)
    Damaged and cut cord with exposed conductor.
    Remind them of just how serious this situation is.
    Ask them: What should they do if they see a cord like this on their site?
  • Trainer’s Notes:
    Review the incident with the participants.
    Ask them what caused the accident?
    Ask them how it could have been prevented?
    Use of GFCI would have prevented the accident. Even with the use of GFCI, there is an instant shock which could have resulted in a ‘fall’.
  • Trainer's Notes:
    Ask them: How many different ways could you contact overhead lines working in the masonry business?
    Assume all overhead lines are energized unless told by the electric company or a competent person.
  • Trainer's Notes:
    Explain that power line contacts account for a large percent of electrocutions.
    Stress the importance of the 10 foot rule.
    Remind them that it also applies to the material they handle and the equipment they use.
    Stress the fact that the power company is very willing to de-energize lines and work with the contractor.
    Clearance also applies to secondary lines going to the house because the lines are usually old, cracked, or maybe even damaged which could
    expose energized parts.
  • Trainer’s Notes:
    Review the incident with the participants.
    Ask them what caused the accident?
    Ask them how it could have been prevented?
    Always look over the jobsite before beginning work.
  • Trainer's Notes:
    Explain that as little 50 volts has the ability to produce enough current flow across the chest to stop the heart within 6 seconds.
    Remind them that most of the time they are dealing with at least twice that amount.
    When masons need electric power, they need to use a qualified person.
    The photo is a violation.
    Abatement: Cover the hole with an approved cover.
  • Trainer's Notes:
    1st hazard - No cover around receptacles leaves exposed energized 120 volt parts.
    Abatement: Since box is outside, this would need a rain tight cover.
    2nd hazard: This box needs to be secured and the non-metallic shield cable (romex) needs to be protected from damage.
    Abatement: Mount box on wall, support romex, and protect from damage.
  • Trainer's Notes:
    Stress the serious nature of these situations.
    Ask participants if they have seen similar situations on their job sites.
    Electrical Safety: As per NFPA 70E, workers should stay at least 4 feet from energized devices.
    Abatement: The left photo needs covers. The electrical installation (in the photo on the right side) needs to be replaced with the proper
    electrical equipment. It has too many hazards and can not be abated. It must be totally redone by a qualified person.
  • Trainer's Notes:
    Explain that equipment grounding helps to safeguard the equipment operator in the event that a malfunction causes the metal frame of the tool to become energized.
    Ground prong on the extension cord is very important. It provides a low resistance path to ground (or source).
  • Trainer's Notes:
    Stress the importance of looking for the ground prong (or the designation for double-insulated) on all equipment, tools and cords.
    If the resistance is equal in the ground and in the workers, the current will flow on both paths.
  • Trainer's Notes:
    Explain the importance of a grounding.
    Remind them that without a ground, in the event of a tool’s internal short circuit, their body will most likely become the ground.
    Missing ground is a violation and will be cited.
  • Trainer's Notes:
    Explain that devices which by-pass the ground prong on any piece of equipment, tool, or cord are extremely dangerous and not permitted on site.
    Remind them that often these devices are referred to as “suicide plugs”. Show audience the devices called ‘suicide plugs.’
    Make sure everyone sees that the ground prong has been removed from the plug on the right and that the cord should be removed from service.
    Remind them of the potentially serious consequences of eliminating the ground path.
  • Trainer's Notes:
    Remind them of the potentially serious consequences of eliminating the ground path. On a three-pronged plug often the other two prongs are the same size and with the ground pin removed, you can reverse the plug, thus reversing the polarity.
    Some double insulated tools use a ground prong to ensure that reverse polarity will not occur.
  • Trainer's Notes:
    Explain that fuses are designed to melt when too much current flows through them
    Explain that circuit breakers are designed to trip open the circuit by electromechanical means.
    GFCI protects people. GFCI are the only electrical devices to protect people. Branch circuits require GFCI protection. Not having
    GFCI in branch circuits (extension cords) is a violation.
  • Trainer's Notes:
    Explain the misconception that a fuse or circuit breaker will save their life in the event of accidental contact with electricity.
    Stress that fuses and circuit breakers protect equipment, not people, and don’t protect against shocks and electrocutions!
    GFCI are very important to protecting people. This can not be stated enough times. Make sure the trainer distinguishes between circuit
    breakers, fuses, and GFCI.
  • Trainer's Notes:
    Explain that unless you plug the machine, tool, or light directly into the building’s permanent wiring, it must be run through a GFCI, or must be included in an Assured Equipment Grounding Conductor Program..
    Remind them that any and all extension cords must be GFCI- protected or color-coded for the Quarter in which they have been inspected by the Competent Person in charge of the Assured Equipment Grounding Conductor Program.
    Show an example of GFCIs.
    Assured Equipment Grounding Conductor Program is a very complicated program that takes a competent person to set up the program and
    provide the training. All workers need to be trained in this program.
  • Trainer's Notes:
    Explain that a GFCI is a fast-acting circuit breaker which senses small imbalances in the circuit caused by current leakage to ground and, in a fraction of a second, shuts off the electricity.
    Explain that the GFCI monitors the current “going” to the tool and compares it to the current “returning”.
    Explain that whenever it senses approximately a 5ma difference it shuts down the circuit in 1/40 of a second.
    A GFCI does work if there is no ground, since it is working based on the difference in current between the two conductors. However, there is no protection against a dead short with no path to ground.
    Further explain about strain relief. Further explain that if the neutral is pulled away, then there is not GFCI protection.
  • Trainer's Notes:
    Discuss and demonstrate various types of GFCI equipment.
    Explain how they can be wired incorrectly and have the indicator lights work but actually fail to protect.
    Explain GFCI-protected receptacles in series.
    Explain how often GFCI should be tested and how.
  • Trainer's Notes:
    This would be a citable offense by OSHA.
  • Trainer's Notes:
    Explain that the GFCI will work without the ground BUT without the ground YOU are still the best path to ground, so if there is a dead short,( like crossed wires), especially if anywhere near your heart, a shock and potential electrocution can still occur. REMEMBER, the GFCI trips at 4-6 milliamps, which is >1000 times the heart’s current. A shock can induce fibrillation BEFORE the GFCI trips.
    Explain that GFCIs must be tested.
    Explain GFCI’s can also be tested without a tester by plugging in a tool, such as a drill, running it and pressing the test button on the GCFI.
    Explain that simply pushing the test button without a load (running tool) is not an accurate test. GFCI’s can be wired wrong and the test button will still operate.
    All of the above testers will only test 120 volt circuits. They will not test the 220 volt circuit going to the brick saw. Remind audience to read
    the instructions that come with the breaker.
  • Trainer's Notes:
    Explain that OSHA does permit this option instead of GFCI protection.
    Tell them that some contractors choose to do both.
    Also if there is a possibility of damage to the electrical device, it must be taken out of service and tested (by a competent person) before being used again.
    Competent person: One who is capable of identifying existing and predictable hazards in the surrounding or working conditions that are unsanitary, hazardous, or dangerous to employees and who has authorization to take prompt corrective measures to eliminate the hazards.
  • Trainer's Notes:
    Discuss strain relief and checking the windings and bushings to the motor.
    The tester used in this photo is a continuity tester.
  • Trainer's Notes:
    Ask the student why it is important to have separate circuits for electric tools and lighting ?
    Double insulated tools and equipment still need GFCI protection.
  • Trainer's Notes:
    Explain to participants that although these make handy home-made extension cord ends, they are not approved for portable and temporary use.
    Explain that the listing and labeling of the box requires it to be fastened to something.
    Also, Romex is not flexible enough for temporary use, and with knock-outs missing there is additional opportunity for problems.
    This violation will be cited by OSHA. Only approved boxes can be used as a splitter box.
  • Trainer's Notes:
    Remind the participants how often cords are used on the site.
    Ask them how cords can get damaged and how to protect cords from damage.
    Explain the rating of cords and read a cord rating to them.
    Demonstrate how to inspect a cord.
    Extension cords can only be repaired by a qualified person.
    Extension cords shall be heavy or extra heavy duty insulation which is stamped on the outer jacket. (see code on cord).
    Extension cords can only be repaired if after being repaired the cord is equal or better than the original condition of the cord.
  • Trainer's Notes:
    Pass around various pieces of acceptable cord types.
    Ask participants to locate markings.
    After participants have located markings, pass around a section of 2-wire household cord.
  • Trainer's Notes:
    This cord should be pulled from service.
    Remind them that splices are not permitted.
    This is a violation of the OSHA Standards.
  • Trainer's Notes:
    The extension cord on the left is a ‘hard, or extra-hard usage’ type.
    The one on the right is not. Discuss the potential for exposure of the conductors.
    Ask them why they think these flat molded cords are not permitted on site?
    Explain to them that the yellow molded cord has the conductors molded into the outside covering only and does not have double the insulation.
    The cord on the right is a violation of the OSHA Standards.
  • Trainer's Notes:
    Ask the participants for their opinion of this kind of “jury-rigging” , given the very real possibility of electrocution?
    If a compliance officer would see either of these homemade electrical devices, it would indicate that there is no competent person on this site. OSHA
    violation.
  • Trainer's Notes:
    Explain that even though most of the time temporary lighting is well out of the worker’s reach, often a piece of conduit, re-bar, and other materials are capable of making contact. Explain the importance of keeping systems in good shape.
    The photos show OSHA violations.
  • Trainer's Notes:
    It may be helpful to have an owner’s manual for a given generator to help explain generator safety.
  • Trainer's Notes:
    Explain that having the physical environment in good shape (i.e., tools, circuits, equipment etc..) is only half of the safety equation. Safe work practices is the other half.
    Need competent person.
  • Trainer's Notes:
    Stress the importance of thinking through each operation to determine whether a tool, material or process will effect their proximity to an energy source.
    Workers and equipment must be 10 feet from overhead lines. Competent person has the knowledge and the authority to correct hazards.
  • Trainer's Notes:
    Remind them that they should not be exposed to energized unguarded electrical circuits.
    Workers shall stay away, 4 feet or more, from exposed energized devices which are 600 volts or less. If panels and disconnects are
    open, see a qualified person to correct the hazard.
  • Trainer's Notes:
    Ask student if they can think of any additional safe work practices?
    Ask them what type of ladders should be used around electricity?
    Is there a competent person on this jobsite?
  • Trainer's Notes:
    Review the Top Five Serious Citations
    Ask the participants how each of the five hazards could be abated.
    1926. 416(a)(1), and/or (2), and/or (3)
    1926.416 (e)(1) and/or (2)
    1926.20(b)(1)
    1926.21(b)(2)
  • Trainer's Notes:
    Stress the importance of thinking through each operation to determine whether a tool, material or process will effect their proximity to an energy source.
  • Trainer's Notes:
    Answers:
    1. TRUE
    2. FALSE
    3. FALSE - 1/20 of an amp (50 ma) going through the chest cavity can stop the heart and be fatal.
    4. TRUE

  • Trainer's Notes:
    Answers:
    5. TRUE
    6. FALSE – 10 feet
    7. TRUE
    8. TRUE
  • Trainer's Notes:
    Answers:
    9. FALSE – only GFCIs are designed to protect the worker.
    10. TRUE
    11. FALSE
    12. FALSE

Transcript

  • 1. Focus Four Hazard Training For Masonry Construction Module 1 - Electrical Safety Susan Harwood Grant Training Program
  • 2. Disclaimer/Usage Notes This material was produced under grant number SH-17793-SH8 from the Occupational Safety and Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government. Images shown may depict situations that are not in compliance with applicable OSHA requirements. These photos are clearly marked as non-compliant. It is not the intent of RMMI to provide compliance-based training in this presentation, the intent is more to address Focus Four hazard awareness in the masonry construction industry, and to recognize overlapping hazards present in many construction workplaces. It is the responsibility of the employer, its subcontractors, and its employees to comply with all pertinent rules and regulations in the jurisdiction in which they work. Copies of all OSHA regulations are available from www.osha.gov. This presentation is intended to discuss Federal regulations only. If this training is held in a state that is operating under an OSHA-approved State Plan, State OSHA requirements for that state must be included in the training. It is assumed that individuals using this presentation or content to augment their training programs will be "qualified" to do so. Developed under an OSHA Susan Harwood Grant, # SH-17793-SH8, by the Rocky Mountain Masonry Institute, Denver, Colorado
  • 3. SUBPART K Masonry Electrical Safety Training Objectives  After completing this unit, you will: – Be familiar with the basic concepts of electricity. – Understand the potential effects of electricity on the human body. – Be able to recognize common electrical hazards associated with masonry work. – Be familiar with electrical protective devices. – Be knowledgeable of safe work practices. 1
  • 4. SUBPART K Masonry Electrical Safety References 29 CFR 1926.400; Subpart K  National Electric Code (NEC)  2
  • 5. SUBPART K Masonry Electrical Safety 3 Take Electricity Seriously  Electricity is the second leading cause of death in construction.  Electrocutions make up 12% of construction fatalities annually.  Over 30,000 non-fatal shocks occur each year.  Over 600 deaths occur annually due to electrocution. Source: Bureau of Labor Statistics
  • 6. SUBPART K Masonry Electrical Safety Electrical Accidents  Leading Causes of Electrical Accidents: – – – – – – – – – – Drilling and cutting through cables Using defective tools, cables and equipment Failure to maintain clearance distance of 10 feet Failure to de-energize circuits and follow Lockout/Tagout procedures Failure to guard live parts from accidental worker contact Unqualified employees working with electricity Improper installation/use of temporary electrical systems and equipment By-passing electrical protective devices Not using GFCI (ground fault circuit interrupters) devices Missing ground prongs on extension cords 4
  • 7. SUBPART K Masonry Electrical Safety 5 Hazards of Electricity      Shock – Most common and can cause electrocution or muscle contraction leading to secondary injury which includes falls Fires – Enough heat or sparks can ignite combustible materials Explosions – Electrical spark can ignite vapors in the air Arc Flash - can cause burns ranging from 14,000 degrees f. to 35,000 degrees f Arc Blast – In a short circuit event copper can expand 67,000 times. The expansion causes a pressure wave. Air also expands adding to the pressure wave
  • 8. SUBPART K Masonry Electrical Safety Fundamentals of Electricity Like Water In A Garden Hose Resistance = Diameter of Hose Example – Larger hose (less resistance), more water flows Voltage = Water Pressure Example – 45 PSI ter low of Wa F Current = Flow Rate Example – 15 gallons per minute 6
  • 9. SUBPART K Masonry Electrical Safety Fundamentals of Electricity Electrical current is the flow of electrons through a conductor.  A conductor is a material that allows electrons to flow through it.  An insulator resists the flow of electrons.  Resistance opposes electron flow.  7
  • 10. SUBPART K Masonry Electrical Safety Current Flows in a Loop or Circuit  Circuits are AC (alternating current) or DC (direct current).  Current is usually AC.  AC current has five parts: (1) Electrical source (2) HOT wire to the tool. (3) The tool itself (4) NEUTRAL wire returns electricity from the tool (5) GROUND 8
  • 11. SUBPART K Masonry Electrical Safety How Shocks Occur Current travels in closed circuits through conductors (water, metal, the human body).  Shock occurs when the body becomes a part of the circuit.  Current enters at one point & leaves at another.  9
  • 12. SUBPART K Masonry Electrical Safety Shocks Occur in Three Ways    Contact with both conductors Contact with one conductor and ground With a tool: contact with “hot” metal part and ground (1), (2) & (3) 10
  • 13. SUBPART K Masonry Electrical Safety Severity of the Shock  Severity of the Shock depends on: – Amount of current • Determined by voltage and resistance to flow – Path through the body – Duration of flow through the body – Other factors such as general health and individual differences. 11
  • 14. SUBPART K Masonry Electrical Safety He sweats - and he dies... Luling, La. - A man was electrocuted when his sweat dripped into the electric drill he was using to build a swing set in his backyard, the coroner said. Richard Miller was pronounced dead Sunday at St. Charles Hospital, said David Vial, St. Charles Parish coroner. Miller, 54, had been using an electric drill in 90 degree heat, Vial said Monday. “Apparently the man was sweating profusely,” Vial said. “He probably was pushing against the drill with his chest and his perspiration went into the drill itself and made a contact.” The Associated Press 12
  • 15. SUBPART K Masonry Electrical Safety 13 Effects of Current Flow        More than 3 milliamps (ma): painful shock More than 10 ma: muscle contraction More than 20 ma: considered severe shock More than 30 ma: lung paralysis - usually temporary More than 50 ma: possible ventricular fibrillation (usually fatal) 100 ma to 4 amps: certain ventricular fibrillation (fatal) Over 4 amps: heart paralysis; severe burns
  • 16. SUBPART K Masonry Electrical Safety 14 Using a 120 volt circuit and resistance for wet & dry skin: E=IR: Voltage=Current x Resistance (Volts) (Amps) (Ohms) So: I=E/R Dry Skin =120/100,000=.0012 amps =1.2ma flowing through body to ground Wet skin =120/1000=.120 amps =120ma flowing through body to ground Remember: 1 Amp = 1000 milliamps
  • 17. SUBPART K Masonry Electrical Safety Effects of Current Flow 15
  • 18. SUBPART K Masonry Electrical Safety Controlling Electrical Hazards    Employers must follow the OSHA Electrical Standards (Subpart K) Electrical installation Subpart K includes four proactive methods: – – – – Electrical Isolation Equipment Grounding Circuit Interruption Safe Work Practices 16
  • 19. SUBPART K Masonry Electrical Safety Electrical Isolation  We can be safe by keeping electricity away from us. We can: – Insulate the conductors. • Example: The insulation on extension cords. – Elevate the conductors. • Example: Overhead powerlines. – Guard the conductors by enclosing them. • Example: Receptacle covers, boxes, & conduit. 17
  • 20. SUBPART K Masonry Electrical Safety Insulating the Conductors     The first way to safeguard workers from electrically energized wires is through insulation. Rubber and plastic is put on wires to prevent shock, fires, short circuits and for strain relief. It is always necessary to check the insulation on equipment and cords before plugging them in. Remember, even the smallest defect will allow leakage! 18
  • 21. SUBPART K Masonry Electrical Safety Defective Extension Cords Photos depict hazardous condition 20 19
  • 22. SUBPART K Masonry Electrical Safety 20 Defective Cord Incident     Depicts hazardous condition Worker attempted to climb scaffold with electric drill. Drill’s cord was damaged with bare wires showing. The bare wire contacted the scaffolding. The worker died!
  • 23. SUBPART K Masonry Electrical Safety Elevating the Conductors     The second way to safeguard workers from electrically energized wires is by elevating them. Wires are often elevated by the power company. It is always necessary to check the location of overhead lines before you begin work each day. Remember, never allow yourself, your tools, or the materials you are working with to be within 10 feet of energized lines! Photo depicts hazardous condition 21
  • 24. SUBPART K Masonry Electrical Safety Working Near Overhead Lines  Clearance of worker and any equipment, tools, materials, or scaffold near uninsulated lines is 10 feet! Photo depicts hazardous condition 22
  • 25. SUBPART K Masonry Electrical Safety 23 Overhead Line Incident A worker was attempting to move mobile scaffold.  Scaffold made contact with 7200 volt line.  The worker died.  Photo depicts hazardous condition
  • 26. SUBPART K Masonry Electrical Safety 24 Guarding the Conductors     The third way to safeguard workers from electrically energized wires is by guarding them. Covers, boxes, and enclosures are often put around conductors to prevent worker contact. It is always necessary to check that electrical boxes and panels are covered and free from missing “knock-outs”. Remember, electric equipment operating at 50 volts or more must be guarded! Photo depicts hazardous condition
  • 27. SUBPART K Masonry Electrical Safety Guarding the Conductors Photos depict hazardous condition 25
  • 28. SUBPART K Masonry Electrical Safety Guarding the Conductors Photos depict hazardous condition 26
  • 29. SUBPART K Masonry Electrical Safety Equipment Grounding  We can be safe by providing a separate, low resistance pathway for electricity when it does not follow normal flow (ground prong).  Grounding gives the stray current somewhere to go and keeps you from becoming part of the circuit. 27
  • 30. SUBPART K Masonry Electrical Safety Can You Rely on Grounding?  Grounding will not work if the electricity can flow through you more easily than the ground. This can happen when: – Your tool doesn’t have a ground pin. – You’re working in wet locations. – You’re touching a metal object. 28
  • 31. SUBPART K Masonry Electrical Safety What Must be Grounded? All circuits and extension cords.  All noncurrent carrying metal parts.  Portable & semi-portable tools and equipment unless double insulated.  29
  • 32. SUBPART K Masonry Electrical Safety Do Not Eliminate the Ground! You become the next-best path for current! Photos depict hazardous condition 30
  • 33. SUBPART K Masonry Electrical Safety 31 Do Not Reverse Polarity The prongs are different sized so you can’t turn the plug around. If you do, the electrical fields within the motor are always energized. If there is moisture present, the case is likely to be “hot”. Even with double-insulated tools, you still could get a shock. Photo depicts hazardous condition
  • 34. SUBPART K Masonry Electrical Safety Circuit Interruption    We can be safer by automatically shutting off the flow of electricity in the event of leakage, overload, or short circuit. Ground Fault Circuit Interrupters (GFCI) are circuit protection (or “overcurrent”) devices that protect you, the worker. Circuit breakers & fuses protect equipment, not you, because they take too much current & too much time to trip. 32
  • 35. SUBPART K Masonry Electrical Safety Circuit Protective Devices  Circuit Breakers and Fuses – Only protect the building, equipment, and tools from heat build-up! – Never depend on circuit breakers or fuses to prevent shocks!  Ground Fault Circuit Interrupter (GFCI) – Is the only device which will protect the worker from shock and electrocution! 33
  • 36. SUBPART K Masonry Electrical Safety 34 GFCI Protection All temporary circuits are required to have GFCI protection or: – Equipment & cords must be included in an Assured Equipment Grounding Conductor Program  An extension cord is a temporary circuit.  Types of GFCIs: receptacle, circuit breaker and portable  Must be wired correctly and tested. 
  • 37. SUBPART K Masonry Electrical Safety How a GFCI Works The GFCI detects ‘leakage’ of 4-6 milliamps & opens the circuit in 1/40th of a second. It will work without the ground plug but not fast enough if you are the ground . 35
  • 38. SUBPART K Masonry Electrical Safety Types of GFCI Protection 36
  • 39. SUBPART K Masonry Electrical Safety 37 Types of GFCI Protection A GFCI breaker must be installed to protect workers using 220V masonry saws.
  • 40. SUBPART K Masonry Electrical Safety GFCI Testers 38
  • 41. SUBPART K Masonry Electrical Safety Assured Equipment Grounding Conductor Program Requires the following: -Written program and specific procedures -Program implemented by a Competent Person (one who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them. -Equipment grounding conductors must be tested (tools, extension cords, and circuits): At least every three months for cords & tools At least every six months for receptacles Results recorded - equipment coded (colored tape) 39
  • 42. SUBPART K Masonry Electrical Safety Checking for Ground Continuity What else we should we notice here? Photo depicts hazardous condition 40
  • 43. SUBPART K Masonry Electrical Safety Temporary Wiring There must be separate circuits for electric tools and lighting, each labeled as such.  Light circuits do not require a GFCI.  – Unless used in a wet location. Test branch circuits before use.  Maintain vertical clearances.  Insulate wires from their supports.  41
  • 44. SUBPART K Masonry Electrical Safety 42 Permanent Equipment in Temporary Use What is wrong with using this as a ‘splitter’? Photo depicts hazardous condition
  • 45. SUBPART K Masonry Electrical Safety Extension Cords and Cables       Must be in good shape without splices. Cannot be secured with staples, nails or bare wire. Must be protected from damage. Must have a ground pin. Should be inspected regularly and pulled from service if defective. Cannot be repaired with electrical or duct tape. Must repair with heat-shrink sleeve or bonding/vulcanizing tape to retain original insulation properties. Photos depict hazardous condition 43
  • 46. SUBPART K Masonry Electrical Safety Acceptable Cord Types All cords must meet the National Electric Code’s (NEC) requirement for Hard/Extra Hard type.  Look for markings stamped on cords.  Acceptable Cord Types  – Extra Hard Use Markings: S, ST, SO, STO – Hard Usage Markings: SJ, SJO, SJT, SJTO 44
  • 47. SUBPART K Masonry Electrical Safety Photo depicts hazardous condition 45
  • 48. SUBPART K Masonry Electrical Safety 46 Extension Cords-What’s the Difference? No flat cords allowed on construction sites!
  • 49. SUBPART K Masonry Electrical Safety Clever Or Foolish? Photos depict hazardous condition 47
  • 50. SUBPART K Masonry Electrical Safety Temporary Lighting All bulbs must be guarded  No broken bulbs or empty sockets  Not suspended by wiring  Low voltage for wet locations  Photos depict hazardous condition 48
  • 51. SUBPART K Masonry Electrical Safety Portable Generators  The frame of the portable generator need not be grounded if: – the generator supplies only cord and plug connected equipment. – The non-current carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame. – GFCI is required if >5kV or if generator provides 220V as well as 110V. 49
  • 52. SUBPART K Masonry Electrical Safety Safe Work Practices    Before work begins, the employer must determine where exposed and concealed electrical circuits are located. Once found, warning signs/labels must be posted. Workers need to know the location, hazards, and protective measures. 50
  • 53. SUBPART K Masonry Electrical Safety Safe Work Practices  Competent Person determines if performance of work could bring contact with energy. – Distance of the worker to the energy source should be considered first. – Tools, materials, and processes should also be considered to see if they could potentially shorten the safe separation distance. • Examples: Metal Ladders, Re-bar, Forklift, Scaffold Frames, etc. 51
  • 54. SUBPART K Masonry Electrical Safety Safe Work Practices  Must not permit work near electric circuits unless the worker is protected by: – De-energizing the circuit and grounding it. – Guarding it effectively by insulation. – Other means (maintaining safe separation)  De-energized circuits and equipment must be locked/tagged out. 52
  • 55. SUBPART K Masonry Electrical Safety Safe Work Practices No metal ladders for or near electrical work.  No wet hands when plugging or unplugging cords/equipment.  No raising or lowering tools by the cord.  Unless equipment is designed for it, cannot be used in damp and wet locations.  Photo depicts hazardous condition 53
  • 56. SUBPART K Masonry Electrical Safety Electrical Safety Common OSHA Citations: – .404(b)(1)(i): Branch circuits: GFCI protection/Assured Equipment Grounding Conductor Program – .404(f)(6): Grounding path – .403(b)(2): Equipment installation and use – .404(b)(1)(ii): GFCI – .403(i)(2)(i): Guarding live parts How can the hazards addressed by these Standards best be corrected, controlled, or eliminated? 54
  • 57. SUBPART K Masonry Electrical Safety 55 Summary – Hazards & Protections Hazards            Inadequate wiring Exposed electrical parts Wires with bad insulation Ungrounded electrical systems and tools Overloaded circuits Damaged power tools and equipment Using the wrong PPE and tools Overhead power lines All hazards are made worse in wet conditions Damaged extension cords Unqualified workers doing electrical work Protective Measures            Proper grounding Use GFCI’s Use fuses and circuit breakers Guard live parts Lockout/Tagout Proper use of flexible cords Close electrical panels by Competent Person Employee training Ensure Competent Person on site Use proper approved electrical equipment Qualified person install electrical devices
  • 58. SUBPART K Masonry Electrical Safety REVIEW QUESTIONS  True or False? 1. Shocks and Electrocutions are the most common type of electrical accident and are the fourth leading cause of worker deaths. 2. The human body will not conduct electricity. 3. It takes at least 1 amp going through a worker to kill them. 4. Insulation on extension cords & elevating power lines are examples of protection through isolation. 56
  • 59. SUBPART K Masonry Electrical Safety REVIEW QUESTIONS  True or False? 5. All portable and semi-portable tools and equipment must be grounded unless double insulated. 6. You, your tools, and the materials you are working with, must never be closer than 3 feet of energized power lines! 7. Electric equipment operating at 50 volts or more must be guarded! 8. All circuits and extension cords must be grounded. 57
  • 60. SUBPART K Masonry Electrical Safety REVIEW QUESTIONS  True or False? 9. Circuit breakers and fuses are designed to protect the worker from electrocution. 10. GFCI protection or Assured Ground Continuity is required on all temporary circuits. 11. Extension cords are not required to have a ground prong when they are GFCIprotected. 12. It is OK to work on a circuit which has not been de-energized. 58