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4/8/20, 9:24 PMFive common causes of electrical fatalities | 2013-10-09 | ISHN

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October 10, 2013

Five common causes of electrical fatalities

Almost all American

workers are exposed to

electrical energy at

sometime during their work

day, and the same electrical

hazards can affect workers in

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4/8/20, 9:24 PMFive common causes of electrical fatalities | 2013-10-09 | ISHN

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different industries. Based on the analysis of these cases, NIOSH

identified five case scenarios that describe the incidents resulting in 244

fatalities:

(1) direct worker contact with an energized powerline (28%);

(2) direct worker contact with energized equipment (21%);

(3) boomed vehicle contact with an energized powerline (18%);

(4) improperly installed or damaged equipment (17%);

(5) conductive equipment contact with an energized powerline (16%).

Scenario 1

Workers in various occupations such as sign technicians, tree trimmers,

utility line workers, and telecommunication workers are often exposed to

overhead powerlines. These exposures can be greatly reduced by isolating

or insulating the energy source from the worker. This can be

accomplished by erecting a physical barrier, by insulating the powerline,

or by following required clearance distances. More than once during

NIOSH fatality investigations, co-workers interviewed did not know the

powerlines posed a hazard, i.e., they thought the powerlines were

insulated.

Scenario 2

Direct worker contact with energized equipment can occur in a variety of

ways. Maintenance technicians might inadvertently contact overhead

crane runway conductors. Electricians or technicians troubleshooting or

testing electric circuitry might contact an energized circuit. Maintenance

workers may fail to replace an isolating plate covering electrical

conductors, exposing passing workers. Compliance with the applicable

articles of the National Electrical Code and lockout/tagout procedures

established by OSHA could eliminate the potential for such contact,

thereby reducing the risk of electrocution.

Scenario 3

4/8/20, 9:24 PMFive common causes of electrical fatalities | 2013-10-09 | ISHN

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Workers guiding suspended loads, or standing against or near a crane or

other boomed vehicle—such as a concrete pumping truck, or derrick truck

—whose boom contacts a powerline are in danger of electrocution. The

risk of electrocution could be reduced if OSHA regulations regarding

clearance distances [(29 CFR 1926.550 (a)(15)] are observed, or if the

required lookout person [29 CFR 1926.550 (a)(15)(iv)] is utilized.

Scenario 4

Improperly installed or damaged equipment can be responsible for

occupational electrocutions in a variety of ways. The most frequently

cited OSHA electrical regulation is improper grounding of equipment or

electrical circuitry. If the frame of a piece of electrical equipment or

machinery does not have a grounding conductor attaching the frame to

ground, as required to divert dangerous fault current to ground, and an

electrical fault occurs, anyone touching that frame and any other object

at ground potential would receive an electrical shock. Should a fault

occur with a grounding conductor present, the circuit would open or trip

as an alert that a problem existed, except in high-resistance grounding

applications. Damaged guards can expose workers to energized

conductors in proximity to their work areas. Additionally, damaged

extension cords or extension cords with their ground prong removed can

expose workers to the danger of electrocution. Failure to maintain a

continuous path to ground can expose entire electrical systems to

damage and can expose the structures within which they are housed and

workers within these structures to electrical and fire hazards.

For example, many electrical systems are installed in a manner that

allows a structure’s water pipes or other conductive conduit to serve as a

continuous path to ground in compliance with the NEC. However, NIOSH

fatality investigations have identified cases of electrocution or fire as a

result of an interruption in a continuous path to ground. During

4/8/20, 9:24 PMFive common causes of electrical fatalities | 2013-10-09 | ISHN

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renovation or repair activities, conductive components may be replaced

by nonconductive components such as PVC pipe, which will interrupt the

path to ground.

This may result in fire due to the intense overheating of components of

the electrical system. Additionally, workers contacting improperly

grounded components while being at ground potential would be exposed

to electric shock.

Scenario 5

The task of positioning or repositioning conductive equipment may place

more than one worker at risk. The weight of mobile scaffolding, grain

augers, or aluminum extension ladders equipped with pendant-operated

lifts often requires more than one worker for positioning or repositioning,

resulting in multiple electrocutions if contact with an overhead powerline

occurs. Using a lookout person, observing required clearance distances, or

lowering this equipment before transport would greatly reduce worker

exposure to any potential electrical hazards present.

Fatality data help to illustrate the magnitude of the electrocution

problem nationally and allow a comparison of the potential risks in

various industries. The information from NIOSH investigations allows for

the identification of more detailed information on electrocution hazards,

such as contact with overhead powerlines, contact with exposed

conductors, inadequate personal protective equipment, and nonexistent

lockout/tagout procedures, or other measures necessary for working

around energized conductors and equipment.

Fatality reports and death certificates identified many of the same

hazards for fatal electrocutions.

The largest number of deaths were in Construction,

Transportation/Communication/Public Utilities, and Manufacturing,

while the highest fatality rates were in the Construction and Mining

industries.

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Linemen were involved in the largest number of electrocutions.

Direct worker contact with an energized powerline caused the largest

number of electrocution deaths.

Almost all of the incidents investigated by NIOSH involved alternating

current. More than half of these incidents involved voltages of more than

600 volts. Of the 147 higher-voltage electrocutions, over two-thirds

involved distribution voltages (7,200-13,800 volts).

While progress has been made in reducing the number of work-related

electrocutions, (50% decrease from 1980-1992), additional efforts are

needed if we are to continue progress towards preventing deaths due to

electrocution, according to NIOSH.

It’s clear the positive and life-saving role training can play in preventing

these tragedies.