Yesterday, the modem and desk lamp in my home office started flashing. I thought the power strip was failing. When I touched the outlet to unplug the power strip, the outlet was hot to touch!!!

I immediately shut the power off and upon examination of the outlet, a copper crimp had been used to pigtail off two black wires. The insulation on the wires and electrical tape had melted and the crimp fell to the floor when I removed the outlet.

This is the second time this has happened. We were fortunate to find this before major damage. The first time I had an electrician inspect the first incident and he made the repair. This one, I rewired with wire nuts and electrical tape. Now I plan to inspect EVERY outlet to remove these crimps.


House was built in 1978 in central CA. Was this normal procedure back then? If so, with new technology and gadgets, is that causing the failure of the crimps. Thank you. Bk.

  • 2
    Yeah, they were experimental in the 70s, including with aluminum wire so watch for that too. You gotta figure, like backstabs (or any jab-and-forget connection) today, they knew at the time the crimps were hokey, and were making a conscious choice to be cheap. Sep 8 '17 at 17:41
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    My house, built in 1965 in California has crimps on copper wire and there have been no issues. Just an comment that they don't always fail.
    – DoxyLover
    Sep 8 '17 at 18:02
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    The crimps are on the ground wires too, and look to be intact with no problems. The problem is with the crimps on the hot wire(s). Thank you both!
    – o5delta
    Sep 8 '17 at 18:05
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    Most stranded wire is crimped to lugs and when splicing large cables crimps are standard. In some areas grounds are still required to be iriversable crimps so yes crimps were used and still are today.
    – Ed Beal
    Sep 8 '17 at 18:09
  • I would not expect crimps on grounds to be an issue, as they should never be carrying any current. What concerns me is the note on the hots. FYI... I would also expect you to see this on the neutrals where they are joined but more concerned about the use you are potentially placing on the circuit. Also advise you take the time to secure a breaker and check all plates/switches. Make notes of condition of each.
    – noybman
    Sep 8 '17 at 21:59

Somewhere between the practice of soldering / taping and the use of wire nuts, Barrel crimps were used to make joints in smaller wire.

If they are done properly they should last a lifetime. Just as any other compression type lug lasts. Millions of ring/fork type lugs are sold and used every year without incident unless they are not crimped tight enough. Then they can heat causing expansion and contraction and eventual failure.

Inspecting the electrical system for more failures would be prudent but I wouldn't rush to replace every joint in the house. If the wires are tight and there is no sign of excessive heating of the joint then they outlast us all.

Good luck and stay safe!


Crimps are NOT (necessarily) a bad thing. Yes it was standard practice and is still done in certain situations. However, in residential jobs it is not what is typically done today.

The more important points are:

  1. Are you maxing out the current draw on the line? Just because a run can support 15A does not make it wise to draw 14A 24/7.
  2. Are you actually cycling current? Drawing 10A then 0A then 10A then 0A is more of an issue in the long run.
  3. As @Harper touched on, is your wiring all copper or is there aluminum involved?

There are specific code driven requirements when aluminum wiring exists. Pigtailing to copper with dielectric grease helping to prevent oxidization is a common approach and then wired to outlets, gfci's, and switches.

When stranded wire is mixed with solid wire it is also imperative to ensure the pigtial is put together correctly, and often secured with electrical tape even though it does not solve the problem of #1 or #2 above.

Given your experience thus far, and the age of your home, it is possible all 3 are happening. Ask your electrician for a recommendation. ESPECIALLY since you have now had this happen twice, it's certainly worth it to fix the issues you are having.

Doing an assessment on all 3 points will give you peace of mind.

  • 1
    thank you all. All wiring is Copper. I did find the crimps on the neutral wire also. The crimp fell off and out at both ends. I will try and take a picture of it and if I find another like it and post it
    – o5delta
    Sep 9 '17 at 22:45
  • So #3 is off the list, and so is a whole mess along with it. @ArchOSX makes a good point, heck, its possible a helper who worked with the contractor or electrician was new to the work, or used the wrong tool or used the tool the wrong way. It makes more sense than a crimped copper copper falling apart unexplicably.
    – noybman
    Sep 10 '17 at 1:14
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    Yes, it sounds like the crimp was probably deployed incompetently. The heat was due to insufficient pressure holding the wires together. Loose connections=heat and possible fire. I would be a little concerned about the rest of the house. Sep 10 '17 at 9:18

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