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Wire being pushed into the back of a back-wired spring clip type receptacle (C) Daniel FriedmanBackwired Electrical Receptacle & Switch Failures
Photos of overheated, failed, burned, shorted back-wired electrical devices

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Back wired electrical receptacle failures:

Photos of failures occurring at or within back-wired electrical receptacles and switches. At page top we illustrate a #14 solid copper wire being pushed into the backwire opening of a common electrical receptacle. The wire has not been pushed fully into the connection as I wanted to show the diameter of the wire entering the push-in connector opening.

This article series illustrates and explains possible electrical failures and fire risk when using the push-in rear connectors on some back-wired electrical devices such as receptacles and switches.



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Photo-Examples of Failures in Back-Wired Electrical Receptacles Illustrate the Failure Condition

Push-in backwired receptacle failure causing fire ignition (C) InspectApedia.com Jess Aronstein Mike Lane 2015

Using the back-wire or push-in type connection points on an electrical receptacle or switch may be just fine, or it may not be reliable nor safe, depending on the age and type of back-wire connector provided.

This article series explains receptacle types, receptacle grounding, connecting wires to the right receptacle terminal screws, electrical wire size, electrical wire color codes, and special receptacles for un-grounded circuits.

The photograph shown here illustrates a failure of a push-in type back-wired electrical receptacle. A fault occurred between the live contact assembly and the grounded receptacle mounting strap (center of the photo) causing fire ignition.

The photograph shows the end result of a long-term and multi-step process, where the overheating push-in wire termination caused carbonization of the bakelite around it, which then faulted (probably when it absorbed moisture from the atmosphere during long "off" periods). - J. Aronstein to D Friedman, private email, 10/29/2015

Dr. Aronstein reports having encountered this failure multiple times and in each occasion the receptacle had been push-in backwired.

Low Contact Force is a Key Performance Difference Between Push-In Wire Connections & Clamp or Screw Terminals on Receptacles & Switches

Low contact force between the wire and the receptacle connector where spring-type push-in backwired terminals are used on receptacles is probably the most significant reason that these connections can be expected to deteriorate over many years.

The small contact area afforded by these connectors, documented at RECEPTACLE WIRE-TO-CONNECTOR CONTACT AREA SIZES may increase that risk.

Watch out:

The key performance difference between the push-in and clamp or screw terminals is the rate of deterioration of the electrical connection. The condition of the connection and connector and rate of deterioration become important over a time frame of years in the typical installed environments (which are highly variable).

There may also be considerable variation in the conditions among the 30 or more push-in wire connections in a typical string of receptacles on each receptacle circuit in a home. Those receptacles that are subject to more frequent use and those subject to heavier loads get more disturbance over time.

A push-in spring connection, inherently much weaker than a screw or clamp type connection, will suffer more disturbance, movement, and weakening than the stronger connectors as the receptacle is used, possibly increasing the risk of a subsequent failure.

The time scale of this deterioration usually is years and decades. This means that the fact that electrical failures or problems with these devices were not seen early in their installed life is no assurance whatsoever that the connectors and devices in an older home will continue to remain safe and reliable in the future.

In other words, the probability of a failure, overheating, and a possible fire and loss increase over time. In a 40 or 50 year old home, push-in wired electrical connections on the home's electrical system are not to be trusted. - J. Aronstein Op. Cit.

Below are front and rear view of another push-in type back-wired electrical receptacle failure. These photographs are provided courtesy Jess Aronstein.

Push-in backwired electrical receptacle failure (C) InspectAPedia.com Jess Aronstein Sprole 2015

and

Push-in backwired electrical receptacle failure (C) InspectAPedia.com Jess Aronstein Sprole 2015

Reader comment: field report of backwired device failures

2017/03/20 J W said:

A very large number of my service calls are due to push in receptacles. I have had burn outs as shown above, but usually the result is an open circuit, often causing lack of current in down line receptacles.

I always replace with side clamp wire receptacles and sometimes home owners or landlords have had me remove and replace all of them in the home.

Reply:

JW

Thank you for your important comment. This topic has been a thorn in the side of safe electrical wiring for some time. It is particularly useful (and compelling) to have feed-back from people who have both expertise and field experience with electrical wiring failures.

If you come across a burned, failed backwired device and can send me photos those would be most helpful. My email is at the page top or bottom CONTACT link.

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Or see WIRE-TO-CONNECTOR FORCE COMPARISONS

Or see RECEPTACLE WIRE-TO-CONNECTOR CONTACT AREA SIZES for a discussion of the areas of wire-to-receptacle contacts on electrical receptacles.

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