Aluminum Wiring and Wire Nut

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Old 10-26-14, 07:44 PM
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Unhappy Aluminum Wiring and Wire Nut

Long story short, my HVAC unit's internal wiring harness seems to have burned itself recently (luckily no fire).

The original part for the wire harness is no longer sold. I bought a new one (revision) that is copper but it's not the exact same connectors ... that's when I thought of doing the splice.

I cut the burnt wires look to cut off the burnt section and splice the two good sections together. That was, to my surprise that it was aluminum inside. Looking at a old thread, it seems like this is not recommended to use a wire nut for AL-AL.

But, maybe, in my case because it's the hvac wiring harness, this may be ok? Specifically, the wires are 18AWG, 600-volt, 105c max temp, stranded (there's 10-12+ strands).
 
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Old 10-26-14, 07:58 PM
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That is most likely plated copper. Aluminum is not used in internal condensor wiring.

18AWG, 600-volt, 105c max temp, stranded (there's 10-12+ strands).
If it were #18 aluminum it would have to be solid.
 
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Old 10-26-14, 08:00 PM
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I doubt that your unit is wired with AL. I suspect it is tinned copper if anything.

Using regular wire nuts for AL to AL or Al to CU is not an approved method. The connector need to be approved for use with AL.
 
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Old 10-27-14, 04:27 AM
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Thanks, you are probably both right that it's tinned/plated copper. Aluminum was what immediately popped into my head.

I guess I can try and scratch off the top coating to see if there's copper?

I bought the ideal brand outdoor/indoor wire nuts. If it's the case that it's tin or plated then the wire nut would be ok?
 
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Old 10-27-14, 04:42 AM
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I bought the ideal brand outdoor/indoor wire nuts. If it's the case that it's tin or plated then the wire nut would be ok?
Yes.

Looking at a old thread, it seems like this is not recommended to use a wire nut for AL-AL.
I also doubt it is aluminum, but if it were here are a couple things to keep in mind. There is only one wire nut that is U.L. Listed for a Cu to Al connection, the Ideal Purple #65 Twister, but they have an unusually high failure rate. There is NO WIRE NUT U.L. Listed for a Al to Al connection, not even the purple Twister by Ideal. The U.S. Consumer Products Safety Commission approves NO WIRE NUT for use with aluminum wire whether it be Al to Al or Al to Cu.

Cut a piece of the suspect wire and look at the end and I think you'll see the wire has a copper core.
 
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