Electric Portable Tools

A review of the use of electrically powered tools is in order because of the many accidents caused by them on a construction project.

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 electrical shock.

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 terminals.

.    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.