Tip of the Month - October 2008
OUTLETS
Source: HOUSES-Henry S. Harrison-3rd Edition
The duplex receptacle was,
until 1960, the most common type of household outlet in use. It
accepts a two-prong plug, the type most often found on lamps and small
appliances. In 1960, the NEC and the MPS required that all
receptacles be of the grounding type, designed to also accept a
three-prong plug. Many small appliances are wired with a third
ground wire that is attached to the frame or metal housing of the
appliance. The third slot in a grounded outlet is connected to a
water pipe or other grounding metal. Grounding of an appliance
using a three–prong plug and receptacle reduces its shock hazard.
Special waterproof receptacles with caps are available for
outside use, clock outlets, TV outlets, locking outlets and a variety
of other special purpose outlets. The receptacle for a 220-volt to 240
volt line is designed to accept only special plugs. A standard
two-prong or three-prong plug cannot be plugged into it. It also
is designed to accept only plugs for appliances using only the exact
number of amperes that it will supply.
Outlets should be located conveniently throughout
the house. The MPS requires that three-prong duplex grounding
outlets should be installed in all habitable rooms so that no point
along the floor line is more that 6 ft. from an outlet. It also
requires that an additional outlet between all doors and between doors
and a fireplace should be supplied (unless the wall is too small for a
piece of furniture); that in rooms without permanent light fixtures, at
least three outlets should be provided regardless of the room size;
that two outlets should be installed in the kitchen over the counters;
and that an outlet should be installed next to the mirror in the
bathroom.