Aluminum-Copper wire nut capacity


  #1  
Old 10-21-22, 02:18 PM
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Aluminum-Copper wire nut capacity

My house, built in 1974, has aluminum wires. All outlets and fixtures have been pigtailed with proper aluminum-copper wire nut connectors (purple ones). It seems that they are of the same size and there is one wire nut connecting 4 aluminum wires together (done by an electrician who pigtailed the house[condo] few years ago). Isn't that too much for one single wire nut? I skimmed through the charts (underwriters' laboratories), and it seems that 4 #10 (or even #12) aluminum wires would exceed the capacity of one wire nut.

The aluminum wires are likely part of a 20amps branch circuit, so I would assume they are #10. I came across this issue due the need of using a neutral wire for a new switch (those are neutral wires) and I would need to connect them to yet another wire to have a neutral available to the new light switch.

EDIT: It may be a 15amps circuit and not a 20amps. So, that would imply that it uses #12 aluminum wires. Went to the basement and checked the labels, but almost all the breakers are 20amps; this one though seems to be 15amps; but cannot be sure given that the previous owner may have used a 15amps breaker instead of a 20amps.
 

Last edited by tk3000; 10-21-22 at 03:38 PM.
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Old 10-21-22, 05:11 PM
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It depends on the wire nut. Manufacturers will list the wire sizes and counts allowed for a particular wire nut either on the packaging or on their website.

We use Ideal wire nuts and their reds can take up to 5 #12 wires.
 
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Old 10-21-22, 05:51 PM
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Tolyn:
Yeah, I know that. But these are wire nuts specifically made for aluminum-copper connections. It seems that there is only one type and size (and manufacturer: ideal). According to the manufacturer's website it seems that four #12 aluminum wires connected together would exceed its rating capacity. Also, I need to pigtail an extra wire to the bundle of four which already exceed the capacity; so likely I would need to add an extra al-cu wire nut -- hopefully there is enough room in the elect box.3

Edit:

The manufacturer states that it could be used with al-cu and cu-cu, but does not say anything about al-al.

On the table it says that "2 #12 AI solid w/1 #10 Cu" is ok, so I would assume that 3 #12 aluminum would be ok as well.

Actually, it seems that one more wire would not work either. Have to look into something else.
 
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Old 10-21-22, 08:14 PM
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The manufacturer states that it could be used with al-cu and cu-cu, but does not say anything about al-al.
Correct. Ideal purple wire nut is not approved for al to al connection. Be careful with Ideal purple wire nut. It is very easy to make bad splice with it and cause over heat. I have seen it many times.
Ideal states "For use only on copper-to-copper or aluminum-to-copper connections. Do not use on aluminum-to-aluminum connections." on their website.


AlumiConn from King Innovation is probably the best connector home owners can use for Al to Al or Al to Cu splices. Downside is it is bulky and expensive. You can buy a bulk package on eBay if you need to make lots of splices.
 
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Old 10-21-22, 09:23 PM
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lambtion:
No, the house has been pigtailed few years ago (by a supposedly reputable electrical company). The work the company performed also passed city inspection. So, I was assuming it was done properly.

I simply stumbled upon the situation when trying to upgrade an exhaust fan switch to one with a timer (thus, the need for a neutral). A bunch of neutral wires were inside and in the back of the elect/junction box, but I noticed that a bundle of 4 aluminum wires were bundled together inside a single purple wire nut. I am not the one who did perform the job, and the setup did not look sound.

Yeah, I was looking into Alumiconn wire connectors for al-cu and al-al, and they seem suitable for this type of situation. I would need two alumiconn four port connectors or an alumiconn four port connector and a purple wire nut in order to hook up a neutral to the new exhaust fan switch. But I am having a hard time finding four ports alumiconn connectors - maybe they don't exist, and the only option is to use 3 3-ports alumiconn connectors or 2 3-ports alumiconn connectors and a purple wire nut.
 

Last edited by tk3000; 10-21-22 at 10:05 PM.
  #6  
Old 10-22-22, 04:27 AM
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Here is instruction sheet that comes with purple wire nut.
https://www.idealind.com/content/dam...-365%20Ins.pdf

Passing inspection does not necessarily mean it is done correctly. It just means inspector did not see.

Crimp style pigtail is the way to go for professional electrician, but the tool is very expensive.

Alumiconn only comes in 2 ports or 3 ports. In order to connect 4 wires together, you will have to use 2 of 3 ports and use jumper wire in between.
 
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Old 10-22-22, 10:58 AM
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If the inspection overlooked such blatant error -- especially for someone who should know a lot about that trade since he/she makes a living doing it -- then what is the point of having an inspection. Yeah, any competent inspector can make mistakes or overlook something once in a while when doing an inspection, but that type of clear-cut error all over the place (several outlets)?

It seems that do not make Alumiconn connectors with 4-ports. Shame on them! Wago lever nuts have connectors with so many ports, and are so practical, reliable, and easy to work with.

Actually, I would need to use either 3 3-port alumiconn connectors or 2 3-port alumiconn connectors along with a purple wire nut given that I would need to pigtail another neutral wire for the new switch. Hopefully, there is enough room in the elect box for all of that.


 

Last edited by tk3000; 10-22-22 at 01:24 PM.
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Old 10-22-22, 01:50 PM
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But these are wire nuts specifically made for aluminum-copper connections
They also carry the UL label, but UL has never tested them. The US Consumer Product Safety Commission cautions against using ANY twist-on connecter with aluminum wiring, they do not approve the Ideal Purple Twister and the Ideal Purple Twister also has an extremely high failure rate.
 
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Old 10-23-22, 10:20 PM
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CasualJoe:

I see where you are coming from. I never really delved into that subject. But there is not much I can do about it, mainly because I live in a condominium. It is good to know though.

So, since it is a condominium, I don't have much control over the decisions, and the wires inside the walls are their responsibility. Besides, the association likely would not listen to me -- as far as they are concerned, they had an electrical company performing the job, and it was approved by the city inspector.

I would imagine that at least it is substantially better than what was in place before: ordinary wire nuts and aluminum wires directly connected to common light switches and power outlets

In any event, I will be moving to a free-standing house soon.
 
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Old 10-27-22, 01:47 PM
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I would imagine that at least it is substantially better than what was in place before: ordinary wire nuts and aluminum wires directly connected to common light switches and power outlets
​​​​​​​I would say it's not any worse than the original installation. I wouldn't approach using the term "Better" at all.
 
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Old 11-07-22, 09:42 AM
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I have the same problem with overloaded boxes due to aluminum wiring being so thick. I looked into Wago's (2273-243 or 2273-222) and talked to a Wago rep. He said Wago's are only approved in Europe where they are used all the time for aluminum connections. I've tried buying but no one will ship here.
 
 

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