Electrical – Reasons why a receptacle would fail


A friend has asked for my help to replace a wall receptacle that has stopped working. I asked if it was loose-fitting or otherwise physically worn out. She said that plugs fit tightly and it generally seems OK.

Are there faults that could cause a receptacle to fail that I should check for while replacing it? Other than physically wearing out, I've never experienced a receptacle that simply quit working.

The house is old, possibly nearing 100 years. The receptacle likely does not have a modern ground wire to it. It was used for her computer and unlikely ever needed to supply more than a few amps.

Best Answer

A GFCI upstream

This outlet may be supplied from a GFCI/RCD outlet upstream, which has tripped or failed. Since you think this circuit doesn't have ground, this would be a good reason to have used a GFCI. People generally use GFCI receptacles, even in odd places, because they are cheaper than GFCI breakers.

Stab connections

A common reason for a socket to fail is the "back stab" connections on the back of the socket. These are holes you jab the wire into, and then "magic springs" hold the wire in. And the socket must cost 50 cents wholesale, which tells you the wizards aren't really making an effort. This is not a quality receptacle, and it will tend to fail there.

Switching to the screw connections helps, and using a more quality $4-tier receptacle also helps. Some of them have screw-and-clamp, where you jab the wires but must use the side screws to clamp the wire, those are fine.

Aluminum wiring

Mainly a problem for homes wired in the 50s and 60s, a reault of having a housing boom at the same time 3/4 of the civilized world is rebuilding from the ashes, which overwhelmed the copper mines. Aluminum wire can be tolerated, but needs special splicing that is beyond the scope of this answer. Ask.

Is it grounded?

It is grounded if there's a continuous grounding path from the receptacle to the panel... and that ground is either wired to the receptacle, or wired to a steel junction box and the receptacle's metal yoke (ears) is bottomed out hard against that metal box. If the yoke bottoms out on plaster or drywall and there's a gap to the metal box, not good enough.

If there is not a good grounding path, then either

  • install a 2-prong receptacle. This is unrealistic, as the tenant will defeat it with cheaters or breaking off ground pins, and you can't allow that.
  • install a GFCI receptacle, or assure that this receptacle is fed from a GFCI receptacle or breaker, rated for personnel protection. Label the receptacle "No Equipment Ground", and "GFCI Protected" if that is not obvious.