Environmental Health and Safety Office (MC 645)
1140 South Paulina Street, Suite 245
Chicago, Illinois 60612-7217
Phone (312) 996 7411
Electrical Safety
Overview
Offices and laboratory equipment that uses electricity is potentially
hazardous and can cause death, serious shock, or burn injuries if
improperly used or maintained. Electricity normally travels through this equipment through electrical
conductors such as wires, switches, motors, circuit boards, and lights. Most metals and moist skin
readily conduct electricity because they offer very little electrical resistance. Substances that offer
higher resistance to the flow of electricity include dry wood, porcelain, or pottery, which can be used
to prevent the flow of electrical current. If a part of the body comes in contact with the electrical
circuit, a shock can occur. The electrical current will enter the body at one point and leave at
another.
The passage of electricity through the body can cause great pain, burns, destruction of tissue,
nerves, and muscles and even death. Factors influencing the effects of electrical shock include the
type of current, voltage, resistance, amperage, pathway through the body, and the duration of
contact. The longer the current flows through the body, the more serious the injury. Injuries are less
severe when the current does not pass through or near nerve centers and vital organs. Electrical
accidents usually occur as a result of faulty or defective equipment, unsafe installation, or misuse of
equipment on the part of office workers.
When electrical current passes through the body, macroshock can occur. There are five major causes
of death by electrical shock in the macroshock situation:
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Almost everyone reacts with violent muscle contractions when a current of 1 to 10
milliamperes flows through an arm or leg. Such reactions may cause secondary actions (i.e.,
falling from a ladder or dropping an object) that may cause serious injury or death.
Ventricular fibrillation usually results when a current of approximately 100 milliamperes flows
from arm to arm for one second. Unless the fibrillation is stopped and normal heartbeat
reestablished within a very short time, death results.
If a current of 10 to 20 milliamperes flows directly through the chest muscles, the induced
muscular contractions can make breathing impossible resulting in asphyxiation within a few
minutes.
Death from electric shock can result from direct respiratory arrest. Usually, this occurs when
current flows through the head. The effect may be temporary (lasting 8 to 10 minutes or
longer) or permanent. In the temporary case, if artificial respiration is promptly applied,
recovery may result.
Death will most likely occur when many amperes of current flow through the body, resulting in
severe burns which can destroy nerve and muscle tissue.
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Environmental Health and Safety Office (MC 645)
1140 South Paulina Street, Suite 245
Chicago, Illinois 60612-7217
Phone (312) 996 7411
Acceptable Electrical Uses
To protect employees, students, and visitors
against electrical accidents, the University
follows these guidelines:
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The use of three-pronged "cheater"
adapters (which eliminate the ground
connection) and multiple-outlet adapters
are prohibited. (pictured below in Figure 1)
All extension cords for 110-120 volt service
to portable power tools must be of
standard heavy duty three-wire cord, one
wire of which is a grounding conductor and
shall be equipped with a three-pronged
grounding-type plug.
Extension cords are not acceptable as
permanent extensions of electrical service
in buildings. They are permissible for such
light load appliances as desk lamps and
clocks provided that:
o The cord is Underwriters Laboratories
(UL) listed, not longer than six feet,
and is in good repair.
o The cord is entirely visible and does not
pass through wall openings, doorways,
partitions, or under rugs.
o The cord is not spliced, tied in knots,
wrapped around metal fixtures, or
draped over pipes
Heavy load appliances, including
refrigerators, freezers, heating devices,
etc., shall be connected directly to
permanent outlets by the service cord
attached to the appliance. No extension
cords are allowed.
Refer to the University of Illinois Hospital, Hospital
Management Policy and Procedure, 01-08-01, Use
of Personal electrical Equipment, Space Heaters,
and Extension cords for specific hospital and clinic
requirements
Ungrounded Equipment
Grounding is a method of protecting
employees from electric shock. By grounding
an electrical system, a low-resistance path to
earth through a ground connection is
intentionally created. When properly done, this
path offers sufficiently low resistance and has
sufficient current-carrying capacity to prevent
the buildup of hazardous voltages. Most fixed
equipment such as large, stationary machines
must be grounded. Cord and plug connected
equipment must be grounded if it is located in
hazardous or wet locations, if operated at
more than 150 volts to ground, or if it is of a
certain type of equipment (such as
refrigerators and air conditioners). Smaller
office equipment, such as coffee pots, would
generally not fall into these categories and
therefore would not have to be grounded.
However much of the newer laboratory and
office equipment is manufactured with
grounded plugs as a precaution (three prong
plugs). In such cases, the equipment should
be used in accordance with the manufacturer's
instructions. In any case, never remove the
third (grounding) prong from any three-prong
piece of equipment. Take caution when dealing
with 2-prongged plugs!
Overloaded Outlets
Insufficient or overloading of electrical outlets
should be avoided. A sufficient number of
outlets will eliminate the need for extension
cords. Overloading electrical circuits and
extension cords can result in a fire. Floor
mounted outlets should be carefully placed to
prevent tripping hazards.
FIGURE 1 Example of a three-prong cheater adapter (left)
and multiple outlet adapter (right). Neither is safe to use.
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Environmental Health and Safety Office (MC 645)
1140 South Paulina Street, Suite 245
Chicago, Illinois 60612-7217
Phone (312) 996 7411
Unsafe/Non-Approved
Equipment
or aisles due to the potential tripping hazard.
If you must run a cord across a walkway,
either tape it down or purchase a cord runner.
The use of poorly maintained or unsafe, poor
quality, non-approved (by national testing
laboratory) coffee makers, radios, lamps, etc.
(often provided by or used by employees)
should be discarded. Such appliances can
develop electrical shorts creating fire and/or
shock hazards. Equipment and cords should be
inspected regularly, and a qualified individual
should make repairs.
Live Parts Unguarded
Defective, Frayed or
Improperly Installed Cords
When the outer jacket of a cord is damaged,
the cord may no longer be water-resistant.
The insulation can absorb moisture, which
may then result in a short circuit or excessive
current leakage to ground. If wires are
exposed, they may cause a shock to a worker
who contacts them. These cords should be
replaced. Electric cords should be examined on
a routine basis for fraying and exposed wiring.
Improper Placement of Cords
A cord should not be pulled or dragged over
nails, hooks, or other sharp objects that may
cause cuts in the insulation. In addition, cords
should never be placed on radiators, steam
pipes, walls, and windows. Particular attention
should be placed on connections behind
furniture, since files and bookcases may be
pushed tightly against electric outlets,
severely bending the cord at the plug.
Electrical Cords Across
Walkways And Work Areas
An adequate number of outlet sockets should
be provided. Extension cords should only be
used in situations where fixed wiring is not
feasible. However, if it is necessary to use an
extension cord, never run it across walkways
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Wall receptacles should be designed and
installed so that no current-carrying parts will
be exposed, and outlet plates should be kept
tight to eliminate the possibility of shock.
Pulling of Plugs to Shut Off
Power
Switches to turn on and off equipment should
be provided, either in the equipment or in the
cords, so that it is not necessary to pull the
plugs to shut off the power. To remove a plug
from an outlet, take a firm grip on and pull the
plug itself. Never pull a plug out by the cord.
Working On "Live Equipment"
Disconnect electrical machines before
cleaning, adjusting, or applying flammable
solutions. If a guard is removed to clean or
repair parts, replace it before testing the
equipment and returning the machine to
service.
Blocking Electrical Panel Doors
If an electrical malfunction should occur, the
panel door, and anything else in front of the
door will become very hot. Electrical panel
doors should always be kept closed, to prevent
"electrical flashover" in the event of an
electrical malfunction.