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Twice in the last two years I have had appliances in my house fail due to (what appears to be) the wire nut being "evaporated."
With my dishwasher, one day the appliance had no power. I pulled the unit out and found that all that was left of the wire nut was the spiral metal piece of it. All of the plastic and melted away, leaving that metal spiral and the ends of the wires for the connection.
A few days ago, the same thing happened with my water heater.
There isn't much to wire nuts that I'm aware of. It just seems suspect that this happened twice. The only thing in common with these two instances is that they both involve appliances that use water. For the record, I don't recall there being any cases of the dishwasher overflowing or the water heater using the emergency pressure release valve.
It appears that the installer used regular building wirenuts for those applications
rather than something more appropriate to the heat/caustic conditions
-OR- the junction box these connections should be in wasn't appropriate.
It is odd that the plastic is melting or decaying. That indicates intense heat. Intense heat comes from a bad connection. It can also occur where you connect aluminum and copper wire together. Check your wire. If it is aluminum you need special connectors. Another possibility is that the wire is undersized for those appliances. It shoudl be 12 GA wire. If it is 14 ga, you could be getting excessive heat.
A junction box has nothing to do with heat, unless it is too small for the number of connections crammed into it. Even then it is not ging to accumulate enough heat to melt a wire nut. That is really really hot.
You need to find out if and why there is so much heat at the connection. It could cause a fire.
Another possibility - sometimes if you overtighten a wire nut, the metal cone pulls out of the placstic, especially ith cheapo wire nuts. Maybe your original electrician did this and just left it that way.
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Quote:
Originally Posted by Coldjensens
It is odd that the plastic is melting or decaying. That indicates intense heat. Intense heat comes from a bad connection. It can also occur where you connect aluminum and copper wire together. Check your wire. If it is aluminum you need special connectors. Another possibility is that the wire is undersized for those appliances. It shoudl be 12 GA wire. If it is 14 ga, you could be getting excessive heat.
A junction box has nothing to do with heat, unless it is too small for the number of connections crammed into it. Even then it is not ging to accumulate enough heat to melt a wire nut. That is really really hot.
You need to find out if and why there is so much heat at the connection. It could cause a fire.
Another possibility - sometimes if you overtighten a wire nut, the metal cone pulls out of the placstic, especially ith cheapo wire nuts. Maybe your original electrician did this and just left it that way.
A little bit loose and they overheat and the plastic outercoating overheats, turns brittle, then eventually just turns to powder. Seen it plenty of times over the past 28-30 years being an Electrician, sloppy initial installation is what it points to. Usually the wire spiral that is left is bluish colored and the insulation on the wire itself is brittle or even melted a bit. Just because they are used on an appliance that uses water, doesn't mean the connections are exposed to water, there is zero reason to use "special" wirenuts for these applications. At a junction there should be no heat so that isn't a factor, and there should be no "caustic" substances either. If there is noticeable heat at a wire junction itself, then the connection is loose.
It is odd that the plastic is melting or decaying. That indicates intense heat. Intense heat comes from a bad connection. It can also occur where you connect aluminum and copper wire together. Check your wire. If it is aluminum you need special connectors. Another possibility is that the wire is undersized for those appliances. It shoudl be 12 GA wire. If it is 14 ga, you could be getting excessive heat.
The bolded is a very good point and one that needs to be checked into. The wire size should also be checked as well. Water Heater should be #10 AWG.
Quote:
Another possibility - sometimes if you overtighten a wire nut, the metal cone pulls out of the placstic, especially ith cheapo wire nuts. Maybe your original electrician did this and just left it that way.
That is all I can think of.
Also true about the cheep crap wirenuts. Maybe they were replaced by a former owner and they did just stuff it back in the box without the outer portion. Just out of curiosity I would like to know if it was on the neutral on the dishwasher... it is amazing how many people don't think it is important to keep the neutral insulated at a connection. Water heater is probably 240 so both legs are "hot" that would just be stupid to think it was OK to close it up without insulation... but I have seen that as well over the years. Nothing surprises me anymore.
When making an electrical connection, any connection, the wires should be tightly twisted against each other, then the wire nut screwed onto the the wires. You should never rely on just the wire nut to make the connection for you. That's how you get bad connections and heat that caused the plastic wire nut to melt. It's a real fire hazard in my opinion. There is special paste you can use on aluminum wires that are spliced (ie twisted together) together to prevent the degradation. It was mainly for houses wired with aluminum during the 70's. It's not typically used on appliance connections to copper.
Quote:
Originally Posted by Bydand
Also true about the cheep crap wire nuts.
Wire nuts are wire nuts in my opinion, the only wire nuts I would consider cheap are are the ones they occasionally give you when you buy a light fixture. And the only reason I dislike them is they tend to be very small, it's far easier to work with orange nuts instead.
Last edited by TechGromit; 12-21-2011 at 10:16 AM..
After 28+ years twisting wire-nuts, I would have to disagree with you about that remark. There are some remarkably crappy wire-nuts out there that you can buy.
After 28+ years twisting wire-nuts, I would have to disagree with you about that remark. There are some remarkably crappy wire-nuts out there that you can buy.
Agreed and there are some really execellent ones. You really notice the difference when you find the good ones, but they are not easy to find.
After 28+ years twisting wire-nuts, I would have to disagree with you about that remark. There are some remarkably crappy wire-nuts out there that you can buy.
This is true. I don't know why anybody would fool with cheap wire nuts, considering that the cheap wire nut can start a fire, burn your house down, and maybe kill you and yours - the good ones are not that expensive.
It's possible that someone used the wrong size wire nut, I'm not sure you can get a too-small one on the wires, but I guess some wingnut could use one that's too big and does not get tight enough.
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