1. Electrical safety is the 4th largest contributor to fatalities in the construction industry, with 5% of deaths due to electric shock or discharge. 2. Conductors readily allow the flow of electricity while insulators have high resistance and prevent electricity from flowing. Water and human skin are normally insulators but become conductors when wet. 3. Electric shock occurs when a person becomes part of an electrical circuit, with current entering and leaving the body. The severity of shock depends on current amount, path through the body, and time in the circuit. Effects range from tingling to cardiac arrest.

1. 1
Electrical Safety in Construction Industry
 4th largest contributor in construction industry
fatalities.
5% contact with electricity or electrical discharge

2. 2
How Electricity Works
 Electricity is a natural energy force.
 Electricity is also a man made energy
force.
 It is essential to modern life and
taken for granted everyday.

3. 3
Conductors & Insulators
Substances with very little resistance to the flow of electrical current are
called conductors. Examples are metals.
Substances with such a high resistance that they can be used to prevent the
flow of electrical current are called insulators. Examples are glass, porcelain,
rubber, plastic, and dry wood..

4. 4
Water is a poor conductor of electricity, but
small amounts of impurities, such as salt and
acid (perspiration contains both), make it a
ready conductor. Therefore, although dry wood
is a poor conductor, when saturated with water
it becomes a ready conductor.
The same is true of human skin. When skin is
dry, it is a poor conductor of electrical current.
When it is moist, it readily conducts electricity.
Use extreme caution when working with
electricity where there is water in the
environment or on the skin.

5. 5
Hazards of Electricity
Electricity
Fire Flashover
Electric Shock
Injuries due to reaction
from electric shock.
Electric Burns
Electric Shock

6. 6
Electrical Safety - Identify Yourself ?
 There are two classifications of employees as related to electricity:
1. Qualified Employees: An employee who has received training in and
has demonstrated skills and knowledge in the construction and
operation of electrical equipment and installations and the hazards
involved.
2. Unqualified Employees: An employee who is not “qualified” and who
faces a risk of electrical shock, burns or other related injuries.
 Engineers
 Inspectors
 Operators
 Supervisors
 Mechanics
 Office workers
 Most people in this room fall into this category…

7. 7
Hazard No 1 - Electric Shock
 Electric Shock
 Thousands of non-fatal electrical shock accidents occur each year
 Hundreds of people die from electrocution each year
 Electrocution remains the fourth (4th) highest cause of industrial fatalities
 All injuries and deaths can be avoided

8. 8
How electric shock occurs
Electricity travels in closed circuits, normally through a conductor. Shock
results when the body becomes part of the electrical circuit - current enters
the body at one point and leaves at another. Typically, shock occurs when a
person contacts the following below:
Both wires of an energized
circuit.
One wire of an energized
circuit and the ground.
A metallic part in contact
with an energized wire
while the person is
also in contact with
the ground.
Metallic parts of electric tools and machines can become energized if there is a
break in the insulation of their wiring. A low-resistance wire between the metallic
case of the tool/machine and the ground – an equipment grounding conductor –
provides a path for the unwanted current to pass directly to the ground. This greatly
reduces the amount of current passing through the body of the person in contact
with the tool or machine. Properly installed, the grounding conductor provides
protection from electric shock.

9. 9
How electric shock affects the body
Three primary factors affect the severity of the shock a person
receives when he or she is a part of an electrical circuit:
 Amount of current flowing through the body (measured in
amperes).
 Path of the current through the body.
 Length of time the body is in the circuit.
Other factors that may affect the severity of the shock are:
 The voltage of the current.
 The presence of moisture in the environment.
 The phase of the heart cycle when the shock occurs.
 The general health of the person prior to the shock.
Effects can range from a barely perceptible tingle to severe burns
and immediate cardiac arrest.
Wet conditions are common during low-voltage electrocutions. Under dry conditions,
human skin is very resistant. Wet skin dramatically drops the body's resistance.

10. 10
Effect of Electric Shock
Current level
(in milliamps)
Probable effect on human body
1 mA
Perception level. Slight tingling sensation. Still dangerous under
certain conditions.
5 mA
Slight shock felt; not painful but disturbing. Average individual can let
go. However, strong involuntary reactions to shocks in this range may
lead to injuries.
6-30 mA
Painful shock, muscular control is lost. This is called the freezing
current or "let-go" range.
50-150 mA
Extreme pain, respiratory arrest, severe muscular contractions.
Individual cannot let go. Death is possible.
1000-4300 mA
Ventricular fibrillation (the rhythmic pumping action of the heart
ceases.) Muscular contraction and nerve damage occur. Death is
most likely.
10,000 mA Cardiac arrest, severe burns and probable death.
Burn + injuries

11. 11
Contact with Power Lines
Overhead and buried power lines at a construction site
are especially hazardous because they carry
extremely high voltage. Fatal electrocution is the
main risk, but burns and falls from elevation are also
hazards. Using tools and equipment that can contact
power lines increases the risk.
Examples of equipment that can contact power
lines:
 Backhoes
 Concrete pumpers
 Cranes
 Long-handled cement finishing floats
 Metal building materials
 Metal ladders
 Raised dump truck beds
 Scaffolds
Overhead power lines are un-
insulated and can carry tens of
thousands of volts, making
them extremely dangerous to
employees who work in their
vicinity.

12. 12
Power Lines
Stay clear from power lines at
least 10 feet
How Do I Avoid Hazards?
Look for overhead power lines and buried
power line indicators. Post warning signs.
Contact utilities for buried power line
locations.
Stay at least 10 feet away from overhead
power lines. Unless you know otherwise,
assume that overhead lines are energized.
De-energize and ground lines when working
near them. Other protective measures include
guarding or insulating the lines.
Use non-conductive wood or fiberglass
ladders when working near power lines.

13. 13
Power Lines
How Do I Avoid Hazards?
Never store materials or equipment under
overhead power lines.
Maintain safe distances between scaffolding
and overhead power lines.
.

14. 14
Main Power Supply Panel
 Must have suitable weather protection.
 Warning sign,notices & barricade
 Earthing of Main Panel.
 Integrity of Panel.
 No looseconnection.

15. 15
Sub Panels & distribution

16. 16
Earthing
 Grounding is the process used to
eliminate unwanted voltage.
 A ground is a physical electrical
connection to the earth.
 Electrical equipment must be properly
grounded.
 Grounding reduces the risk of being
shocked or electrocuted.

17. 17
Improper Earthing

18. 18
Improper Earthing
 The ground pin safely returns
leakage current to ground.
 Never remove the ground pin.
 Double insulated tools are labelled

19. 19
Damaged Insulation
 Never use tools or extension cords with
damaged insulation.
 Do not run extension cords through
doors or windows.

20. 20
Overload circuit
 Overloaded circuits can cause
fires.
 Use proper circuit breakers.
 Use a 3-way extension with a
GFCI instead in a wet
environment.

21. 21
Power Tools
 Never carry a tool by the cord.
 Never yank the cord to disconnect it from the
receptacle.
 Keep cords away from heat, oil, and sharp edges
(including the cutting surface of a power saw or
drill).
 Disconnect tools when not in use, before
servicing, and when changing accessories such
as blades, bits, etc.

22. 22
Power Tools
 Avoid accidental starting. Do not hold fingers on the switch button while
carrying a plugged-in tool.
 Use gloves and appropriate safety footwear when using electric tools.
 Store electric tools in a dry place when not in use.
 Do not use electric tools in damp or wet locations unless they are
approved for that purpose.
 Keep work areas well lighted when operating electric tools.
 Ensure that cords from electric tools do not present a tripping hazard.
 Remove all damaged portable electric tools from use and tag them: "Do
Not Use."
 Use double-insulated tools.

23. 23
Accident Prevention
 A willing, positive attitude
towards safety will help make a
safer work environment.
 Always consider these safety
precautions:
 Personal protective
equipment (PPE),
 Inspect tools,
 Ground fault circuit
interrupters (GFCIs),
 Lock-out/tag-out

24. 24
Lock Out – Tag Out
 Workers must ensure electricity is off and
“locked-out” before work is performed.
 The switch must be tagged.
 The tag lets others know why the switch is off.

25. 25

26. 26
What is portable tool ?
Portable equipment is not a part of fixed installation but when used is connected
to a fixed equipment by flexible cable, plug socket or compressed air point.
Types of portable tool is determined by their
power source
 Air Operated
.Electrically operated
 Liquid fuel operated
 Hydraulic fuel operated
 Powder actuated

27. 27
Hazards associated with Power Tools
Workers using hand and power tools may
be exposed to these hazards:
 Objects that fall, fly, are abrasive, or splash
 Harmful dusts, fumes, mists, vapors, and gases
 Frayed or damaged electrical cords, hazardous
connections and improper grounding
 Vibration and impact
Risks
Electric shock
• Flash burns
• Falling
• Hand and Eye injuries
• Hearing loss
• Crushing, cuts or losing a body part
• Ergonomic injuries

28. 28
Portable Tool
 Video

29. 29
Electric Power Tools : General
Electric Chord
 Don’t carry portable tools by the cord
 Don’t yank cord or hose to disconnect it
 Keep cords and hoses away from heat, oil, and sharp edges
 Replace damaged cords immediately!
Prevent Electrical Shock
 Frayed electrical wires.
 Earth wire often removed.
 Use of power from multiple plug points.

30. 30
Guarding
Machine guards must protect the
operator and others from:
 Point of operation
 In-running nip points
 Rotating parts
 Flying chips and sparks
Nip Point
Radial arm saw
equipped with
an upper and
lower blade
guard

31. 31
Oxy acetylene cutting General Safety Precaution
 keep hoses away from sharp edges and
abrasive surfaces or where vehicles can run
over them;
 Do not allow hot metal or spatter to fall on
hoses;
 maintain all equipment and regularly check its
condition.
 Use the correct lighting-up procedure.
 Make sure the blowpipe is fitted with spring-
loaded non-return valves.
 Never allow oil or grease to come into contact
with oxygen valves or cylinder fittings;

32. 32
Liquid Power Tools General Safety Precaution
 Main hazard : Fuel / Vapours
 Use only approved flammable liquid containers
 Before refilling a fuel-powered tool tank, shut down
the engine and allow it to cool
 Refuel at least 10 feet from combustible materials

33. 33
Management of Portable Tools