# Wires melted down in Furnace



## dsymonds (Jun 7, 2016)

Hi all, 

Today my air conditioner stopped running in the middle of the day - we have an HVAC unit outside, central air, and an electric furnace. All controlled by the thermostat on the wall. Thermostat was blank, nothing on the screen, and unresponsive. I opened it up, but no batteries, just wiring leading to the furnace in the garage. Shut off the power, and opened up the furnace to find a bit of scorching/burnt spot on the insulation inside, and some burned/melted wires. Pictures attached show the burnt wires and information about the unit. It's a Carrier brand Electric Furnace.

You can see a couple of wires joined together with a blue cap that look nice and tidy, and then you can see the melted disaster next to it with a burned cap that's fallen to the bottom of the unit.

Now, I don't know anything about furnaces and very little about working with electrical wiring. 

My first thought though is that I should be able to cut these wires back, screw a new cap on them, and fire up the furnace. If I do that, are they going to just melt down again? Is there a way to get at the root of this problem and fix it so it doesn't happen again? 

Thanks everyone for any help you can provide!


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## joed (Mar 13, 2005)

Your plan should be fine. It was most likely a poorly made connection that overheated over time and finally burnt up.


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## dsymonds (Jun 7, 2016)

Thanks joed, I'll give it a try! Hopefully that solves the problem and has me back up and running.


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## dsymonds (Jun 7, 2016)

Update! I picked up a new cap, cut back the melted wires and then stripped about 3/4" off the ends, screwed on a new cap, and then flipped the power back on to the furnace. Thing fired right up, thermostat display back on, cold air blowing, all's working normally. Feels pretty good to DIY! Thanks for the help joed!


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## bernie963 (Dec 18, 2010)

hi, just an observation.

The large black wires, are they copper or aluminum? If aluminum you may have the wrong kind of wirenuts, which may explain the overheating of the connection. looks like there is an aluminum ground/neutral wire in the background. You may want to post this on the electrical forum.

bernie


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## dsymonds (Jun 7, 2016)

Hmm... Okay thanks Bernie - the black wire is aluminum, yellow is copper. I'll do some reading and see if maybe there's a different wirenut option I should swap out. Thanks for looking out!


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## bernie963 (Dec 18, 2010)

great, think you need a purple wire nut. not an electrician, but would post on electrical side of the diy forum, good, great advice over there.

better safe than sorry.

bernie


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## supers05 (May 23, 2015)

If it's aluminum, (scratch it with a knife, and it'll be silver colour not copper color,) then you'll need special wire nuts. The new one will only last a short while before burning up again. 

Cheers!


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## user_12345a (Nov 23, 2014)

the special nut has some type of anti-corrosion compound in it right? stops the aluminum and copper from reacting or something.


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## dsymonds (Jun 7, 2016)

Oh cool! Great to know - I'll go pick up a purple wore it tomorrow and swap it out. Thanks for the help guys!


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## dsymonds (Jun 7, 2016)

Purple *wirenut* - apparently my phone doesn't know what that is. To be fair, I didn't know what that was yesterday. We're learning together.


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## bernie963 (Dec 18, 2010)

change both of them, you need two.....I would also use some anticorrosive paste. but again not an electrician. where does the neutral terminate, you may need three. 

bernie


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## roughneck (Nov 28, 2014)

There will be no neutral, it's a 208/230V furnace. I don't care for wire nuts in high amp draw situations, I much prefer split bolt connectors, wrapped in mastic, and sealed with tape. Very rare to overheat a connection then.


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## gwebb417 (Mar 15, 2018)

I was trying to figure out why in the world these wires would have burned up in my furnace and this old thread told me why. I appreciate everyone that took the time to post!


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## rmeador9905 (10 mo ago)

I know this is an old thread but I had recently googled my problem and this site’s thread and image showed up. I can’t find any similar images that match what my problem is. This thread is close and related to my problem. I do believe after reading these comments that whoever installed this did not use the proper purple connectors for aluminum and copper. My problem is I know that these wires need to be cleaned up a bit and given the proper connectors just like how the original guy did with his post here. My blue wires look pretty bad and one of my blue wires don’t seem to connect to anything. I need to know where these wires need to go and to which place. I wished this post showed the full component because it’s just such a close match to my unit.


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## user_12345a (Nov 23, 2014)

start your own thread


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## supers05 (May 23, 2015)

You'll need to replace some of that wiring. You'll need 14awg for any of the control wiring and appropriate connectors. You'll need a wire stripper and crimper. You'll need whatever the larger wire is. All of it needs to be rated for the same temp as the original.

@beenthere or other mods please make this a separate thread.


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## Temperreign (16 d ago)

Furnace stopped working all of a sudden. Checked the wires, found that its burnt. So redid the wirings, but now furnace is not working. Its on, but nothing works, not even the fan.


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## roughneck (Nov 28, 2014)

Temperreign said:


> Furnace stopped working all of a sudden. Checked the wires, found that its burnt. So redid the wirings, but now furnace is not working. Its on, but nothing works, not even the fan.


This is an old dead thread. Start your own with all the information about your unit. We have no idea what you have.


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