A review of the use of electrically powered tools is in order
because of the many accidents caused by them on a construction
What follows is a typical occurrence, taken from
the file of a national safety agency: A mechanic was standing
on the top of a form, about six feet from floor level, preparing
to drill holes with an electric drill. The mechanic had his
arm around a metal pole for support. When the drill was turned
on, the man received a shock and could not release his grip
on the drill. Another mechanic, working nearby, immediately
pulled the plug, cutting off the power. The injured mechanic
sustained burns on the neck and both hands.
Assuming the man was standing on a wood form that
was off the floor or surface level, his body resistance was
considerably lessened. The dampness of perspiration plus
his placing his arm around the pole all contributes to the
Grounding portable electric tools is the most
efficient way of safeguarding an operator. If there is any
defect or short inside the tool, the current is drained from
the metal frame through the ground wire and does not pass
through the operator's body.
Ground fault protection in temporary power systems
used on construction sites is the modern method of protecting
the operator of electrical equipment from the slightest shock.
A periodic check of portable electrical equipment, using specialized
measuring devices to determine any possible internal short
circuits, is suggested in lieu of ground fault protectors.
Insulating platforms, rubber mats, and rubber
gloves are other means to guard against electrical shock.
Generally, all tools should be inspected by their
operators frequently for the following obvious malfunctions:
. Defective or broken insulation or cord.
. Improper or poorly made connections to
. Broken or otherwise defective plugs.
. Loose or broken switches.
. Brushes sparking.
Make sure that OSHA regulations for equipment
grounding are followed when working with cord-and-plug-connected
equipment that requires grounding, including use of ground
fault circuit interrupters (GFCI) or an effective equipment
grounding conductor program for all cord sets, receptacles
(temporary), and equipment connected by cord and plug.