Electrical Safety-L&I v1

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ELECTRICAL SAFETY

OSHA 29 CFR 1910 SUBPART SBureau of Workers Comp

PA Training for Health & Safety(PATHS)

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AN AVERAGE OF ONE WORKER ISELECTROCUTED ON THE JOB EVERY DAY!

There are four main types of electrical injuries:

Electrocution (death due to electrical shock)

Electrical Shock

Burns

Falls

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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 toelectricity.

GROUNDING = A conductive connection to the earth

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Received when current passesthrough the body.

Severity of the shock depends on:

Path of current through the body

Amountof current flowingthrough the body

Length of time the body is in thecircuit

LOW VOLTAGE DOES NOT MEANLOW HAZARD!

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Currents greater than 75mA(1/1,000 of an ampere) cancause ventricular fibrillation(rapid, ineffective heartbeat)

Will cause death in a fewminutes unless adefibrillator is used.

75mA is not much currenta small power drill uses30 times as much.

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When two wires have different potential voltages,current will flow if they are connected.

In most household wiring the black wires are at

110 volts relative to ground.

The white wires are at zero volts because theyare connected to ground.

Contact with an energized (live) black wirewhile touching the white grounded wire =ELECTRICAL SHOCK!

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Contact with an energized wire/any energizedelectrical component + any grounded object =SHOCK!

You can even receive an electrical shock when youare not in contact with a ground.

CONTACT BOTH WIRES OF A 240 VOLT CABLE =

SHOCK, POSSIBLE ELECTROCUTION!

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Are the most common shock-related nonfatal injury

Occur when you touch electrical

wiring or equipment that isimproperly used or maintained

Typically occurs on the hands

Very serious injury that needsimmediate attention

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Electrical shock can also causeindirect or secondary injuries.

Employees working in anelevated location whoexperience a shock can fall,resulting in serious injury or

even death.

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A hazard exists when a conductor istoo small to safely carry the current.Example: Using a portable tool withan extension cord that has a wire

too small for the tool.

Tool draws more current than cordcan handle = overheating,possible fire without tripping thecircuit breaker

Circuit breaker could be the rightsize for the circuit but not for the

smaller wire extension cord

Wire Gauge

WIRE

Wire gauge measureswires ranging in size from

number 36 to 0 American

wire gauge (AWG)

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Too many devices pluggedinto circuit = wires heat to

very high temperature =possible fire

Wire insulation melts =arcing may occur = fire in

area where overloadexists (even inside a wall)

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Shut off electricity flow in the event of anoverload or ground-fault in the circuit.

Include fuses, circuit breakers and ground-fault circuit interrupters, or CGCI.

Fuses and circuit breakers are over currentdevices (too much current = fuses melt and

circuit breakers trip open).

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Protects you from dangerous electricalshock.

Detects a difference in current betweenthe black and white circuit wires (could

happen when electrical equipment is notworking properly causing a currentleakage known as ground fault).

Ground fault detected = GFCI can shutoff electricity flow in as little as 1/40 ofa second protecting you from adangerous shock.

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Some of the most frequently violated OSHAstandards.

Metal parts of an electrical wiring system that we

touch should be at 0 volts relative to ground (switchplates, ceiling light fixtures, conduit, etc.).

Housings of motors, appliances or tools that areplugged in to improperly grounded circuits may

become energized.

If you come into contact with an improperly groundedelectrical device YOU WILL GET SHOCKED!

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GROUNDING PATH

The path to ground from circuits, equipment andenclosures must be permanent and continuous.

The violation shown here is an extension cord withthe third/grounding prong missing.

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HAND-HELD ELECTRICAL TOOLS:

Hand-held electrical tools pose apotential danger because they makecontinuous good contact with the

hand.

To protect you from shock, burns andelectrocution, tools must:

Have a 3-wire cord with ground and beplugged into a grounded receptacle

Be double insulated

Be powered by a low-voltage isolation

transformer 16PPT-008-01


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Must guard live parts of electricequipment operating at > 50 voltsagainst accidental contact by:

Approved cabinets/enclosures

Location or permanent partitions(thereby only accessible to qualifiedpersons)

Elevation of 8 feet or more above thefloor or working surface

Mark entrances to guarded locationswith conspicuous warning signs

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Where electricalequipment is inlocations that it can

suffer physicaldamage it must beguarded.

The violation shown

here is physicaldamage to conduit.

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Junction boxes, pull boxesand fittings must haveapproved covers.

Unused openings in cabinets,boxes and fittings must beclosed (no missingknockouts).

Photo shows violations ofthese two requirements.

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Are more vulnerable than fixed wiring.

Should not be used if recognized wiring methods can be used

instead.

Flexible cords can be damaged by: Aging

Door or window edges

Staples or fastenings

Abrasion from adjacent materials

Activities in the area

Improper use of flexible cords can cause shocks, burns or fire.

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Pendant or Fixture Portable lamps, Stationary equipment

Wiring tools or appliances to facilitate interchange

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Substitute for Run through walls, ceilings Concealed behind

fixed wiring floors, doors, or windows or attached to

building surfaces

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Tripped circuit breakers or blown fuses

Warm tools, wires, cords, connections or

junction boxes

GFCI that shuts off a circuit

Worn or frayed insulation around wire or

connection

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Train employees working with electrical equipmentin safe working practices including:

De-energizing electrical equipment beforeinspecting or making repairs

Using electric tools in good repair

Using good judgment when working nearenergized lines

Using appropriate protective equipment, or PPE

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Hazards

- Inadequate wiring

- - Exposed electrical parts

- Wires with bad insulation

- Ungrounded electrical tools/systems

- Overloaded circuits

- Damaged power tools/equipment

- Overhead power lines

- All hazards are made worse in wetconditions!

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Protective Measures

Proper grounding

Using GFCIs

Using fuses and circuit breakers

Proper use of flexible cords

Training

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The bottom line with electricity:

RESPECT

COMMON SENSE

SAFETY

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Electrical Safety-L&I v1

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