ELECTRICAL ELECTRICAL

SAFETYSAFETY

ELECTRICAL ELECTRICAL

SAFETYSAFETY

Part 2: Working SafelyPart 2: Working Safely

ELECTRICITY - THE DANGERS

SHOCK

BURNS

ARC FLASH

FALLS

ELECTRICAL SHOCK

An electrical shock is a current flow through the body.

The shock occurs when any part of your body completes a circuit by being:

• In contact with two wires• In contact with a wire and ground• In contact with a metal part that is

in contact with a wire in a circuit and ground.

ELECTRICAL SHOCK

The response could range from a faint tingling sensation to death.

You can perceive a currentas low as 1 milliamp.

At 5 mA you will feel a slight shock. Most people can let go.

ELECTRICAL SHOCK

“Can’t Let Go” Current

10 mA to 30 mA

Painful shockand sustainedmuscle contraction.

ELECTRICAL SHOCK

50 mA to 150 mAExtreme pain, respiratory arrest, severemuscle contractions, possible death

1,000 mA to 4,300 mAVentricular fibrillation, muscle contractions,nerve damage, deathlikely.

ELECTRICAL SHOCK

ELECTRICAL SHOCK

The duration and the amount of currentaffect the severity of an electrical shockinjury.

Death can occur in 2 seconds with a current of 0.1 amps (100 milliamps).

100 mA for 3 seconds is as dangerous as 900 mA for 0.03 seconds.

ELECTRICAL SHOCK

Other factors that may affect the severity of the shock are:

• The voltage of the current.• The presence of moisture.

• The phase of the heart cycle when the shock occurs.

• The general health of the person prior to the shock.

ELECTRICAL SHOCK

High voltages increase shock injuriesbecause a higher voltage produces agreater current.

I = E/R

Resistance - the lower the resistance, thegreater the current will be.

R = E/I

ELECTRICAL SHOCK

Resistance between  major  extremities  of  an  average human body is 1,500 ohms hand to hand or hand to foot.

 If you grabbed a wire carrying 120 volts alternating current  how much current would flow through your body?

I = E/R

ELECTRICAL SHOCK PATHWAYS

4. Left hand left foot path

3. Right handright foot path

2. Right foot left foot path

1. Right hand left hand

ELECTRICAL BURNS

Electrical burns are the result of heat generated by the flow of electric current through the body.

The dark spot is where thecurrent entered the body.

ELECTRICAL BURNS

Electricity arced through the air as a result of a power box explosion.

The arc was drawn to this man’s arm pits because of perspiration.

ELECTRICAL BURNS

Current exited this man at his knees, catching his clothing on fire and burning his upper leg.

ELECTRICAL BURNS

The current exited the foot of this man. Becauseof severe internal injuries, the foot had to be amputated a few days later.

ELECTRICAL BURNS

This worker was shocked by a tool he was holding.

A few days later.

ARC FLASH

An arc flash is a shortcircuit through the air.

It can occur if a conductiveobject gets too close to ahigh-amp current sourceor by equipment failure such as opening orclosing disconnects.

FALLS

Workers who get shocked while on a ladder or other elevated location can fall, resulting in serious injury or death.

ELECTRICAL HAZARDS

• Exposed electrical parts• Overhead power lines• Inadequate wiring• Defective insulation

• Wet conditions

• Improper grounding

• Improper PPE• Improper tools• Overloaded circuits

Electrical shocks, fires or falls can result from:

ELECTRICAL HAZARDS

Exposed Electrical Parts

ELECTRICAL HAZARDS

Overhead Power Lines

NIOSH Case StudyUntrained worker raising a 21 foot fence rail under a 7,200 volt power line. Worker was electrocuted.

ELECTRICAL HAZARDS

Inadequate Wiring Wire Gauge - wire size or diameter

Ampacity - the maximum amount of current a wire can carry safely without overheating

Incorrect wiring practices can cause fires! If you touch live electrical parts, you will be shocked. Overloaded wires get hot!

ELECTRICAL HAZARDS

Copper Wire Ampacity Table   

Wire Gauge  Maximum Ampacity 

14   15  12   20 10   30  

8   45  6   65   4   85  2   115   0   150 

2/0   175  4/0   250

ELECTRICAL HAZARDS

Defective Insulation

ELECTRICAL HAZARDS

Defective Insulation

Screw penetrated insulation creating asmall arc flash.

ELECTRICAL HAZARDS

Wet Conditions

Wet clothing, high humidity, and perspiration also increase your chances of being electrocuted.

ELECTRICAL HAZARDS

Improper grounding

ELECTRICAL HAZARDS

Improper grounding

ELECTRICAL HAZARDS

Overloaded Circuits

Too much current in a circuit can lead to a fire or electrical shock.

THE REGULATIONS

CalOSHA Low voltage (600V) Electrical Safety Orders

Article 3, § 2320.1Only qualified persons shall work on electrical equipment or systems.

A qualified person is defined as a person designated by the employer, who by reason of experience or instruction has demonstrated familiarity with the operation to be performed and the hazards involved.

THE REGULATIONS

§ 2320.2Work SHALL NOT be perform on energized parts of equipment or systems until the following conditions are met:

1.Responsible supervision has determined that the work is to be performed while the equipment or system are energized.

2.Involved personnel have received instructionson the work techniques and hazards involvedin working on energized equipment.

THE REGULATIONS

§ 2320.2 (cont’d)

3. Suitable personal protective equipment and safeguards (approved insulated gloves or insulated tools) are provided and used.

4. Approved insulated glovesshall be worn for voltages in excess of 250 volts to ground.

THE REGULATIONS

§ 2320.2 (cont’d)

5. Suitable barriers or approved insulating material shall be provided and used to prevent accidental contact with energized parts.

6. Suitable eye protection has been provided and used.

THE REGULATIONS

§ 2320.2 (cont’d)

7. Where required for personnel protection, suitable barricades, tags, or signs are in place.

THE REGULATIONS

§ 2320.2 (cont’d)

• Each employee who is exposed to the hazardsof flames or electric arcs wears apparel that, when exposed to flames or electric arcs, does not increase the extent of injury that would be sustained by the employee.

THE REGULATIONS

§ 2320.3All electrical equipment and systems shall be treated as energized until tested or otherwise proven to be de-energized.

THE REGULATIONS

General Safety Orders § 3314 (g)

A hazardous energy control procedure shall be developed and utilized by the employer when employees are engaged in the cleaning, repairing, servicing, setting-up or adjusting of prime movers, machinery and equipment.

LOCKOUT/TAGOUT

LOCKOUT/TAGOUT

Overview of Procedures

Must use own lock and keep key on his/her person until job is done.

Procedures apply to all Sources of energy - electrical, thermal, hydraulic, pneumatic, mechanical, etc.

LOCKOUT/TAGOUT

Notify all affected employees.

Identify all applicable isolating devices - breakers, switches, valves, etc.

LOCKOUT/TAGOUT

Obtain a padlock and tag from lockoutstation.

Isolate source of power at the circuit breaker on MCC paneland at other sourcesof hazardous energy.

LOCKOUT/TAGOUT

On the tag, write name, date, time and why equipment is locked out.

BLOCK

DRAIN

BLEED

TEST

Test to be sure there is no release of hazardous energy.

LOCKOUT/TAGOUT

Always take precautions to guard against

the possibility of faulty switches or short

circuits when locking out equipment.

Test the equipment with a meter when

doing electrical work.

THE REGULATIONS

Do not use conductive measuring tapes or ropes when working near energized parts of equipment.

Legibly mark each motor controller to indicate the motor it controls and provide a corresponding marking on each motor.

When a circuit is discontinued, remove the conductors from the raceway or treat the circuit as if it is in use.

THE REGULATIONS

Do not use conductive fish tape in raceways entering enclosures with exposed energized parts unless the parts are isolated by barriers.

At least 3 feet of cleared space (no storage) shall be available in the direction of access to control panels, circuit breakers, switchboards, fused switches, and similar equipment.

THE REGULATIONS

All electrical equipment shall have markings giving voltage, current, wattage, or other ratings.

Circuit breakers shall clearly indicate whether they are in the open “off” or closed “on” position.

THE REGULATIONS

Flexible cords or cables SHALL NOT be used • as a substitute for fixed wiring of a structure, • where run through holes in walls, ceilings or floors, • where run through doorways, windows or similar openings, • where attached to building surfaces, or • where concealed behind building walls,

ceilings or floors

THE REGULATIONS

Flexible cords shall be used only in continuous lengths without splice or tap.

Hard service flexible cords No. 12 or larger can be spliced as long as the splice retains the insulation, outer sheath properties, and usage characteristics of the cord.

GROUND FAULT CIRCUITINTERRUPTER

Use a GFCI when working on circuits or using electrical equipment in damp or wet areas.

DOUBLE INSULATED TOOLS

Use double insulated toolsif GFCI is not available.

Always check cord and plug on all power tools before use

ELECTRICAL FIRES

NEVER put water on an electrical fire.

Use Class C or ABC fire extinguishers.

THE REGULATIONS

Wrist watches, rings, or other jewelry should not be worn while working with or around machinery with moving parts in which such objects may be caught, or around electrically energized equipment.

BE SAFE !

THE

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