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Duplex receptacles
are the most common wiring device. Many types are available. The traditional duplex outlet has screw terminals around which
wire is wrapped to make contact. Then the screw is tightened. Some have holes designed to receive and hold a stripped wire
conductor. That eliminates wrapping the wire around a screw contact and tightening the screw. Other receptacles have both
screw terminals and insert holes. Some are side wired. Others are wired at the back.
Many duplex receptacles have a removable tab between the screw
terminals on each side. Remove the tab to isolate one part of the receptacle from the other. These are commonly used for switched
outlets. Some residential rooms are wired so that a switch by the entrance controls one or more outlets where table lamps
will be installed. Outlets with tabs can also be wired to two different circuits.
Clock hanger receptacles are usually mounted high on a wall. They have a recessed single
outlet for a clock. They also have a tab to hold the clock. This is a decorative item, so many colors and styles are available.
Clock hanger outlets are usually connected to an unswitched circuit. Locking receptacles come in a variety of sizes and configurations. Each service load
capacity has a different size and configuration as set by NEMA (National Electrical Manufacturers' Association) standards.
They're made that way so that appliances that use the receptacles can use only receptacles rated at the correct capacity.
Locking receptacles can be wall-mounted in a box or may be attached to an extension cord.
Be careful
when selecting trim plates for locking receptacles. The size of the receptacle face varies with the service rating. A 20-amp,
4-wire receptacle is larger than a 20-amp, 3-wire receptacle. Locking receptacles are commonly called twist-lock devices because
they must be rotated or twisted when inserted and removed.
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Standard-grade
devices used in residences will be the least expensive because they're made in great quantity and carried by every electrical
supplier. Less common devices are made to meet special requirements and constructed of special materials. For example, switches
and trim plates made of nylon are intended for heavy use. They cost more than standard residential-grade devices and may not
be stocked by your local supplier. Every modern wiring device has a voltage and amperage rating. This rating has an effect on cost. Usually,
the greater the ampacity and voltage rating, the higher the cost. Devices intended to meet exacting specifications or to serve in special applications
are said to be specification grade. Usually these devices are made with more expensive contact material, are designed with
special features, or are built to be particularly durable. That increases the cost, often to several times the cost of the
standard-grade device. But the added cost may be a good investment from the owner's standpoint. For example, one specification-grade
convenience outlet has contact material with better shape-retention characteristics. That ensures better electrical contact
after years of hard use. You've probably seen duplex outlets that will hardly hold an electrical plug in place after a year
or two of service. Most manufacturers offer wiring devices with smooth surfaces that stay cleaner longer -- and are easier to clean when
they do get soiled. Older switch covers had decorative grooves that accumulated smudges and were hard to clean. Standard colors for wiring
devices are ivory, white and brown. Other colors are available but will cost more.
Some devices have built-in grounding. There are two
common types of grounded devices. One has a screw or terminal for attaching a ground conductor. The other has a special spring
on one of the mounting screws. This spring provides a positive ground through the device frame to the mounting screw and on
to a metal-backed outlet box. Automatic grounding devices cost a little more but install a little faster than the type with
a grounding terminal or grounding screw, because the electrician saves one connection
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PARKO HOME RENOVATIONS, Phone: (734) 812-3884
43812 Leeann Lane Canton, Michigan 48187 Written "By
Ron Parko" Author
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