Electrical Receptacles/Outlets

© 2011 Dr. Ray Franco, PhD., PE    r.a.franco@ieee.org



Anatomy of a Residential 15-Amp Duplex Receptacle

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Photo: Leviton Duplex Receptacle

Front and Back of a Leviton Duplex Receptacle.

Photo: Receptacle without Cover

Duplex Receptacle with Face Removed.

Photo: Location of Manufacturer's Data

Interior Parts of a Duplex Receptacle.

Photo: Receptacle without Body and Male Plug

Duplex Receptacle and Male Plug without Plastic Body.

Photo Screw and Stab-In Receptacle Connections

Screw and Stab-In Receptacle Connections.

Photo: Receptacle Screw Connection

Screw Connection to Neutral Bus.

Photo: Receptacle Stab-In Connection

Stab-In Connection to Neutral Bus.

It is not necessary for a receptacle to have something plugged into it for it to cause a fire. The reason that there are two screw terminals on each bus is so that power can be supply to another receptacle or device. Hence, electrical current may be passing through the receptacle even though it has nothing plugged into it.

Stab-in / Push-in connections were common in the 1970's and 1980's. In 1996, UL Standard 498 was revised to only permit stab-in (push-in) connections with solid copper conductors that were size AWG #14. The manufactures reduced the size of the holes so that AWG #12 wire would not fit. AWG #12 wire is thicker and more stiff than AWG #14 wire. When the receptacle was pushed into the outlet box, too much pressure was being inserted on the spring metal gripper, and this was causing loose connections.

On duplex receptacles, there is a break tap between the screws terminals on both the "hot" and neutral buses. This allows the duplex receptacle to be spilt into two receptacles. A common use for this is to control one of the receptacles from a wall switch that turns on a table lamp.


Case History - F10-051: Loose Screw Connection

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Photo: Damaged Receptacle due to Loose Screw

Damaged Receptacle due to Loose Screw Connection.

Photo: Receptacle Not Rated for Aluminum (AL)

Receptacle Rated for Copper (CU) - Not Rated for Aluminum (AL).


Mobile Home Receptacles

The National Electrical Code, Section 300.14, allows for integral enclosure receptacles with brackets that secure the receptacle to the wall. They do not require a separate receptacle box. The wire connections are made by jaws that accept multiple wires and displace the wire insulation. Only the sheath or outer jacket must be stripped from the cable. The receptacles are designed to be used only with nonmetallic (type NM) sheathed cables (Romex). These are primarily used in mobile homes and manufactured building.

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Photo: Front Mobile Home Receptacle

Some Integral Enclosure Receptacles have an Underlying Small Faceplate and an Outer Faceplate that hides the Swing-Arm Screws.

Photo: Receptacle Not Rated for Aluminum (AL)

Integral Receptacle Enclosure and Swing-Arm Bracket.

Photo: Receptacle Not Rated for Aluminum (AL)

To Ensure a Connection, there are Two Splicing Jaws for each Wire.


 

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