1. ELECTRICAL SAFETY!
It’s shocking!
OSHA 29 CFR

2. Introduction
An average of one worker is electrocuted on the job every day.
There are four main types of electrical injuries:
Electrocution (death due to electrical shock)
Electrical shock
Burns
Falls

3. Electrical Terminology
Current – the movement of electrical charge
Resistance – opposition to current flow
Voltage – a measure of electrical force
Conductors – substances, such as metals, that have little resistance to electricity
Insulators – substances, such as wood, rubber, glass, and bakelite, that have high resistance to electricity
Grounding – a conductive connection to the earth which acts as a protective measure

4. Leading causes of injury
Unsafe work practices
(cause of 75% of fatalities)
Working with unsafe equipment
Working in an unsafe environment

5. Qualified worker vs. Unqualified Worker
OSHA Definitions
Qualified worker vs. Unqualified Worker
Qualified
One who is familiar with the construction and operation of the equipment and hazards involved (licensed electrician). Or
One who is undergoing “on-the-job” training and has demonstrated competency in performing the duties safely (apprentice).

6. OSHA Definitions Qualified workers Unqualified workers
How to identify exposed energized parts
How to safeguard or work on energized parts
Unqualified workers
How electricity works
Risks of working with energized equipment
Tasks to be performed only by qualified workers

7. Electrical Shock Received when current passes through the body
Severity of the shock depends on:
Path of current through the body
Amount of current flowing through the body
Length of time the body is in the circuit
LOW VOLTAGE DOES NOT MEAN LOW HAZARD

8. Electrical Shock Dangers of Electrical Shock Defibrillator in use
Currents greater than 75 mA* can cause ventricular fibrillation (rapid, ineffective heartbeat)
Will cause death in a few minutes unless a defibrillator is used
75 mA is not much current – a small power drill uses 30 times as much
Defibrillator in use
* mA = milliampere = 1/1,000 of an ampere

9. Electrical Shock How is an electrical shock received?
When two wires have different potential differences (voltages), current will flow if they are connected together.
In most household wiring, the black wires are at 110 volts relative to ground.
The white wires are at zero volts because they are connected to ground.
If you come into contact with an energized (live) black wire, and you are also in contact with the white grounded wire, current will pass through your body and YOU WILL RECEIVE A SHOCK.

10. Electrical Shock
If you are in contact with an energized wire or any energized electrical component, and also with any grounded object, YOU WILL RECEIVE A SHOCK!!
You can even receive a shock when you are not in contact with a ground.
If you contact both wires of a 240-volt cable, YOU WILL RECEIVE A SHOCK and possibly be electrocuted.

11. Electrical Hazards
Shock
Arc
Blast

13. Rules of Electricity Electricity travels in a completed circuit
Electricity always travels in the path of least resistance
Electricity tries to travel to the ground

14. Effects on the Human Body
1 mA: Can be felt by the body
2-10 mA: Minor shock, might result in a fall
10-25 mA: Loss of muscle control, may not be
able to let go of the current
25-75 mA: Painful, may lead to collapse or death
mA: Last 1/4 second, immediately fatal
110/120 Volts = 60 mA 220/240 Volts = 120 mA
440/480 Volts = 240 mA

15. Severity Of Shock Depends On: Amount of current flowing through body
The path it takes through the body
Elapsed time during shock

16. Body’s Resistance Skin offers most of the body’s electrical resistance
Increased resistance
Thick and callused skin (foot or hand)
Dry skin
Decreased resistance
Thin skin (inner forearm)
Wet or sweaty skin
Broken or abraded skin (scratches)

17. Conductor vs. Insulator
Stops electricity
Does Not Conduct electricity
Conductor
Transfers electricity

18. General Electrical Hazards
High-voltage overhead power lines
Damaged insulation on wires
Digging or trenching near buried lines
Broken switches or plugs
Overloaded circuits
Overheated appliances or tools

19. Hazard Control Injuries typically occur when:
Procedures are inappropriate
Procedures are not followed
Safety systems are circumvented

20. Portable Power Tools Inspect portable power tools before every use!
Never use damaged equipment.
Tag it out of service
Have it repaired or replaced

21. Portable Electric Equipment
UL approved equipment and cords
Graded for hazardous locations
Extension cords must have a ground wire polarity plug.
Inspect for frays, breaks or other damage to the cord insulation
Inspect for grease, oil or chemicals on cords
Do not unplug or raise equipment by cord
Do not use around combustible atmospheres
(“Intrinsically Safe” only)
Work in dry area - avoid water

22. Extension Cords Inspect and check for capacity For temporary work only
Do not use as a rope to pull or lift objects
Should not be fastened with staples or hung over hooks

23. Electrical Cord Inspection
Deformed or mission pins
Damaged outer jacket or insulation
Evidence of internal damage
If damaged, take out of service until repaired

24. Grounding Equipment
Most electrical equipment is designed with a grounding system
Do not use equipment with damaged grounding connectors
Do not use adapters that interrupt the grounding connection

25. Static Electricity Created when materials rub together
Can cause shocks or even minor skin burns
Reduced or prevented by:
Proper grounding
Rubber matting
Grounding wires, gloves, or shoes

26. Ground Fault Circuit Interrupters
GFCIs reduce the likelihood of fatal shocks
Detect small amount of earth current and automatically switch off the power
Used with extension cords and portable tools
Fuses and circuit breakers protect equipment, not people

27. Most effective piece of safety gear ever created…

28. contact with electricity!
Never touch anyone in
contact with electricity!
What to do in emergencies:
Shut off power
Call for emergency help
Administer First Aid/CPR
If unable to shut off power, use a wooden chair, pole, or PVC to free the person.

29. Training
Train employees working with electric equipment in safe work practices, including:
Deenergizing electric equipment before inspecting or making repairs
Using electric tools that are in good repair
Using good judgment when working near energized lines
Using appropriate protective equipment

30. Summary Protective Measures Hazards Proper grounding Inadequate wiring
Using GFCI’s
Using fuses and circuit breakers
Guarding live parts
Proper use of flexible cords
Training
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