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Electrical Receptacles/Outlets


Structure of a Residential 15-Amp Duplex Receptacle

 

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Leviton Duplex Receptical
Front and Back of a Leviton Duplex Receptacle.
Receptacle without Cover
Duplex Receptacle with Face Removed.
Interior Parts of a Duplex Receptacle
Interior Parts of a Duplex Receptacle
Receptacle without Body and Male Plug
Duplex Receptacle and Male Plug without Plastic Body.
Screw and Stab-In Receptacle Connections
Screw and Stab-In Receptacle Connections.
Receptacle Screw Connection
Screw Connection to Neutral Bus.
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

Aluminum connections are especially susceptible to loose connection due to creep.

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Damaged Receptacle due to Loose Screw Connection
Damaged Receptacle due to Loose Screw Connection.
IReceptacle Rated for Copper (CU) - Not Rated for Aluminum (AL)
Receptacle Rated for Copper (CU) - Not Rated for Aluminum (AL).

Structure of Mobile Home Receptacles

The National Electrical Code (NEC), Chapter 3, Section 300.15(E), allows for integral enclosure receptacles and light switches with brackets that secure the device to the wall. They do not require a separate junction box, nor are they mounted to a stud. The integral boxes are designed to be used only with nonmetallic (type NM) sheathed cables (Romex). Only the sheath or outer jacket must be stripped from the cable. The wire connections are made by jaws that accept multiple wires and displace (cut) the wire insulation. They are primarily used in mobile homes and manufactured buildings.

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Photo: Front Mobile Home Receptacle
Integral Enclosure Receptacles with Swing-Arms Screws
Integral Receptacle Enclosure and Swing-Arm Bracket
Integral Receptacle Enclosure and Swing-Arm Bracket.
Integral Receptacle Wire Connection
To Ensure a Connection, there are Two Splicing Jaws for each Wire.
Second View of Splicing Jaws
Second View of the Splicing Jaws.
Splicing Jaws with Wires
Splicing Jaws with Wires Removed.
Wire with Insulation Cut by Splicing Jaws
There is not a lot of wire in contact with the splicing jaws.
Mobile Home Light Switch
Mobile Home Light Switches also have the Integral Enclosure.

Structure of a Ground-Fault Circuit-Interrupter (GFCI) Receptacle

A ground-fault circuit-interrupter is a device that interrupts electricity to the load when the fault current to ground exceed a predetermined value. The fault current is the difference in the line current and the neutral current. For Class A devices, the predetermined value of the fault current is 6 mA (6/1000 amps). For fault currents between 6 mA and 264 mA, class A devices must interrupt electricity to the load according to the following equation: T = (20/I)^(1.43). When I = 6 mA, T = 5.6 sec; when I = 264 mA, T = 0.025 sec. A plot of this curve is well below the curve that causes heart fibrillation and death in heathy adults [Ref.: Leviton GFCI Brochure]. Underwriters Laboratories UL 943 is the Standard for Ground-Fault Circuit-Interrupters. GFCI were introduced in the National Electrical Code in 1968. Now they are required in all wet locations, within 6 feet of any sink, in garage/carports and outside locations.

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Front of GFCI Receptacle
Front of the Leviton GFCI Receptacle.
 
Front of GFCI Receptacle
Back of the Leviton GFCI Receptacle.
 
Rust on Frame of GFCI Receptacle
Side View of GFCI Receptacle with Face Removed.
GFCI Receptacle PC Board
GFCI - Difference Current Transformer and Relay.
GFCI Difference Current Transformer
GFCI - Difference Transformer Winding.
GFCI Difference Current Transformer
GFCI - Back of Printed Circuit Board.
GFCI Difference Current Transformer
Older Leviton GFCI - Difference Current Transformer.

Case History - Water Damaged GFCI

This Ground Fault Circuit Interrupter (GFCI) receptacle was given to me by Reid Sampey with Joe Gay Electric in Vicksburg, MS. It was on outside of a home without a waterproof cover. Water leaked into the receptacle.

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Back of GFCI Receptalce
Melted Hole in the Back of a GFCI Receptacle.
Front of GFCI Receptacle
There was no Damage to the Front of the GFCI Receptacle.
Rust on Frame of GFCI Receptacle
Definite Signs of Rust inside the GFCI Receptacle.
GFCI Receptacle PC Board
GFCI Receptacle Printed Circuit Board.
GFCI Difference Current Transformer
The Hole was at the Difference Current Transformer.