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I recently completed replacing all outlets and switches in my house. In just about each room in the house one outlet had 3 black and 3 white wires going into it. The receptacles I purchased had room for max 2. You could side wire or backstab. I side wire as is recommended. For these outlets I created pigtails with the 3 existing wires and a 4th wire to go to the receptacle.

Yesterday, after replacing the last switch, I flipped on the power in the room and noticed half the receptacles were not working. These are all on the same circuit that the switch was on. I checked all the receptacles and there were no issues. However, the wirenut on the pigtail I created for one of the receptacles melted. I am stumped how this melted. I replaced the pigtail and all is working fine. But I don’t want this to happen again.

Can someone chime in with anything I did incorrectly?

Details: Hot side melted, 15 amp circuit, 14 gauge wire, 15 amp receptacle, Red wing twist wire nut used, Electrical tape used at bottom of wire nut, South wire 14 solid thhn black wire (used to receptacle)

user
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Jordan Alhadeff
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    I think Harper will come along and give you a tutorial on wire nuts: Twist hard. **Really hard**. Then **pull test**. Basically, a loose wire comes *mostly* out, arcs a bunch = small fire = melts until the breaker kicks in and stops it. Related: Why did you need electrical tape? Electrical tape has its uses, but should not be needed for routine pigtails. – manassehkatz-Moving 2 Codidact Dec 20 '20 at 22:20
  • Thank you. I do twist very hard and even use pliers to continue tightening after finger tight. I believe I saw that it is advised to use electrical tape on the wire nut over the sheathed wire at the bottom of the nut – Jordan Alhadeff Dec 20 '20 at 22:29
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    If the wire is stripped the correct length and the wire nut is installed correctly, there is no need for electrical tape, and it usually is a sign that the nut wasn't installed correctly. The one use it can have is to bind a large number of wires in positoon to get the nut on in the first place without one of them slipping too far forward or backwards, but then you want to remove it to do the "pull test" after the nut is on. – Ecnerwal Dec 20 '20 at 22:50
  • Thank you. Based on what I am reading, sounds like user error. I am thinking of switching to the push in wire connector. Thoughts on those? – Jordan Alhadeff Dec 20 '20 at 23:08
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    The copper did not melt. The plastic wire nut did – Jordan Alhadeff Dec 20 '20 at 23:24
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    Just for the Brits & others who like me are going, "What the heck is a wire nut?" - https://diy.stackexchange.com/questions/10144/why-are-wire-nuts-not-used-in-the-uk – Tetsujin Dec 21 '20 at 11:48
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    @JordanAlhadeff the push in connectors are very much not recommend if they're the spring loaded type, the spring gets weak over time and often leads to the same issue you've had already - melted things and malfunctions. If you can get a nicer respectable with slide in connections that are clamped by a screw, those are nice. – nexus_2006 Dec 21 '20 at 13:35

1 Answers1

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Why do you tape the wire nuts?

I can't speak for you... but generally... The usual reason people tape wire nuts is because, in their experience, the splice falls apart if they don't. Well, if they fall apart that easily, it is a defective connection that is prone to arc faults. Arc faults make a LOT of heat and will do just that.

The other thing about taping wire nuts is, they preclude doing a pull test. You can't do a proper pull test on a taped nut.

A pull test is, hold the nut very firmly, then pull on the wire so hard that the nut slips out of your fingers. I'm talking really hard. Do that for each wire.

Tightening "really hard" is good, but not conclusive.

The problem is that certain craft errors assembling the wires can cause the connection to fail even though you tightened really hard. E.G. the wires are not even (staggered) when inserting them. Stripping too little will also do it.

Here's how you can "post-mortem" whether that was the problem. Go back to all your other wire nut splices that you've ever done, and give them the full "pull test". From that, you will have a sampling of how good your wire-nut splices are. If you have any fail, that suggests technique may be the root of your problem.

Abandoning wire-nuts for other splice techniques is like learning how to ride a bike, and quitting the first time you fall off. You can't learn until you test and pay attention to the feedback the test gives you.

Harper - Reinstate Monica
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    Thank you, Harper. I appreciate the time and detail in your response. I will do as you suggested. I overestimated the fool proof of wire nuts and now know that each wire needs the pull test and that over tightening does not make up for pull test. – Jordan Alhadeff Dec 20 '20 at 23:45
  • Are there any tools or tips on proper pigtails? I am using pliers grabbing all 4 wires and twisting. My pigtails are not the prettiest but ensure all wires are touching – Jordan Alhadeff Dec 20 '20 at 23:56
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    Yea I'm gonna say it: this is another reason people ought to suggest Wago lever-nuts. They're quite a bit easier for a beginner to get right the first try, on top of the other ergonomics they already provide. Ok I'll see myself out. ;) – GManNickG Dec 21 '20 at 06:30
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    This is precisely why the very concept of wire-nuts terrifies me. – SiHa Dec 21 '20 at 09:17
  • @SiHa -- I personally think the Wago lever-nuts are pretty good myself, but they have one limitation that keeps them from being a complete solution: you can't get them to take wires fatter than 10AWG, AIUI. ILSCO's MAC-Block is a more universal solution, but requires a torque screwdriver... – ThreePhaseEel Dec 22 '20 at 03:09
  • @ThreePhaseEel - Yes, I've used the Wago blocks a few times now and love them. Anything larger than 2.5mm² I'd use some sort of screw-fixture anyway. – SiHa Dec 22 '20 at 07:06
  • @SiHa -- sadly, UL 1953 listed PDBs (fixed, single-or-multipole, screw-terminal connection means) don't become a practical option until you hit oh 4AWG or so, or are working in a big box *anyway* (such as inside a loadcenter cabinet). The MAC-Block and not-related-but-similar-idea Alumiconn are screw-termination based, but in a "floating" style like a wirenut – ThreePhaseEel Dec 22 '20 at 12:47
  • @SiHa *So did bicycles, how do they stay up????... but I tried, examined failure, learned, iterated. Now they're not so bad*. The key to understanding wire nuts is to unscrew your first 50 nuts and see how they came out. Wire nuts re-use, so you can correct, then put the nut back on. Once you *see what you are doing*, you get the hang of it. – Harper - Reinstate Monica Dec 22 '20 at 23:52
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    @Harper-ReinstateMonica. Indeed. when used correctly, they are perfectly safe. My problem is that there is so much scope for them to go wrong when *not* fitted correctly by a less-than-competent person. And let's be honest here, there are plenty of people who fit that category who are messing with electricity regardless of whether they should be or not. Anyway - end of discussion. I don't like 'em, you do - and that's fine. – SiHa Dec 23 '20 at 10:40