Connecting CU & AL wiring together

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So I finally saw my first aluminum wiring today.
Have heard about for years, of course, but this is the first time I'd actually seen it in the wild. Working on an apt. complex built in the late '70s; client asked me to wire the bath exhaust fan to the light switch so the fan would come on with the light (bath walls were covered with mildew, another of today's tasks of which was to remove).
Upon opening the box, I could see what at first looked like tinned copper leads, but sure 'nuf, they were aluminum. So OK, clearly I wasn't just going to put in a copper pigtail there and call it a day.
Thinking I had to buy some kind of special connector to attach the CU to AL, I went to the local hardware store (Orchard Supply), where I was shown a little tube of stuff from GB (Gardner Bender) called "Ox-Gard" that you just schmear on the wires and connector to inhibit corrosion. Cheap and a neat solution. (It's black. Looks kind of like roofing cement.)
So I actually learned something today.
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On 4/3/2010 8:23 PM, David Nebenzahl wrote:

The shmear stuff is just half of it; you also have to use special connectors that are approved for both AL and CU (I forget the exact marking) Look for Ideal purple wire nuts.
Bob
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And expect to pay near $3 per nut. But they come with the antioxidant goop inside.
KC
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On 4/3/2010 4:42 PM zxcvbob spake thus:

Interesting: the instructions for the goop just say to use it on all wires and the connector, which I did. Isn't the metal inside regular wire nuts steel or zinc, which should be compatible with both CU or AL?
If necessary I'll buy a "special" wire nut and replace it next time I go back there.
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On Sat, 03 Apr 2010 17:59:25 -0800, David Nebenzahl

in it for expediency.
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On Sat, 03 Apr 2010 21:37:26 -0400, snipped-for-privacy@snyder.on.ca wrote:

You can read two different opinions about the Ideal 65 "twister" The U/L says it is OK and the CSPC says it is a fire hazard. The opinions spin off from there. The other method available to the homeowner and most of the trade is the King Innovation Alumicon device that is basically a 3 hole bus bar with an insulating cover.
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On 4/3/2010 7:18 PM snipped-for-privacy@aol.com spake thus:

So what would you do if you needed to connect a CU pigtail to AL wiring?
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On Sat, 03 Apr 2010 20:48:15 -0800, David Nebenzahl

I would use the alumicon device
The alumicon device is the same technology as the bus bars in your panel and there has never been a problem with them.
Second choice would be the twister if it was a low current application. Another option if a receptacle is present is to use a CO/ALr device with copper on one set of terminals and aluminum on the other. If you are doing the whole house AMP/Tyco makes the CopAlum splicing system that CPSC seems to like but it is a proprietary connector that needs a special tool and a certified installer. I have always been curious about the lobbying that took place when CPSC said CopAlum was the only method they would endorse (prior to the Alumicon)
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On 4/4/2010 12:13 AM, snipped-for-privacy@aol.com wrote:

someone that owned a house for 36 year with several 15/12ga aluminum branch circuits. When they 1st started having problems in the early 70s, it was said to used switches and receptacles rated for Al. They then came out with the CuAlr stuff. I don't know what the older Al rated stuff was, but they said the CuAlr was different. I know the screws where bronzy looking. All of the problems I saw, in my neighborhood, were on circuits using the "push-ins" instead of the screws to daisy chain outlet to outlet. 3M, at the time, came out with a wirenut that was listed as connecting copper to aluminum. Also, the crimp connector, mentioned in this thread, was eventually claimed to be the only acceptable way to deal with the problem. That all said, I used the 3M wirenuts (there was no goo in them) to pigtail all my connections. I never had a problem, but many people that never touched their wiring didn't either. The wirenuts produced today by 3M look the same, but don't mention aluminum, as far a I know. I have used the 3M units in my house exclusively. I think, emphasize think, most of the problem where the push-in terminals. And, I think, most of the bad press for the push-ins was probably related to aluminum wire usage. In my subdivision, the early houses used aluminum with push-ins: problems. The next vintage house used them on regular outlets, but on screws; I never heard of problems. The 3rd vintage used CuAlr outlets; never heard of problems. These are just my random thoughts, YRMV from this.
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That's pretty much what I've heard. That aluminum doesn't like to be backstabbed.
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wrote:

We had a good presentation from AlCan at one of our IAEI meetings. They point out the original wire was alloy 1350, the same wire they used for overhead transmission lines, and it was not engineered for the kind of service you have in device wiring. It broke easily and the thermal expansion rate was higher. The new AA8000 is stiffer and has a better thermal coefficient. The CO/ALr device does, in fact, have a different screw. They are not steel, they are a brass alloy that closely tracks the expansion rate of the AA-8000 alloy. There are also ridges in the base that bite into the wire a bit. When you get to the lug type devices (bus bars etc) they are generally aluminum in the first place so they don't have any expansion issues at all. They actually perform better with aluminum wire than with copper in tests.
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Art Todesco wrote:

Far as I know, backstabs were never approved for use with aluminum. They have enough problems with copper - they should never be used with aluminum. You can't use the ones available now because the #12 aluminum wire used for 15A circuits doesn't fit any more.

UL changed the standards about 1971. I don't know if 3M was listed for aluminum before, but only Ideal 65 wirenuts are now (and Alumicon, which is not a wire nut).
From extensive testing on aluminum connections, 3M Scotchlocks were recommended, used with antioxide paste and techniques detailed in http://www.inspectapedia.com/aluminum/alreduce.htm#1C The author says that Alumicon, a newer product, is better.
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On 4/3/2010 8:13 PM snipped-for-privacy@aol.com spake thus:

Except that this is inside a *switch box*, remember? Fully populated with two duplex devices (receptacles and switches) and a bunch of wires, so no room for such a device.

Well, I guess it's low current: one wall light fixture and a ceiling fan.
Anyhoo, I used the wire nut + goop approach.
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If there is not enough room inside the electrical box that is in place, then replace that box with a larger one which has more room in it...
If the walls are open you have many ways you could deal with this...
A 4" square box with a 2-gang trim ring sounds like a good idea if you have the wall open and need more room inside than a standard switch box...
~ Evan
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On 4/5/2010 2:04 AM Evan spake thus:

That's a *totally ridiculous* suggestion. Do you even think before you start typing?
The customer--my client--owns an apartment building built in the late 1970s. He's not about to have me rip out a perfectly sound switchbox in the bathroom just to accomodate your idea of the proper fix.
Sheesh.
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You said you required more space in the box to utilize the devices recommended by another poster's method of making the Cu-Al connection...
It is NOT ridiculous to suggest a larger size electrical box when you have one that is as you put it: "Fully populated with two duplex devices (receptacles and switches) and a bunch of wires, so no room for such a device." which would raise concerns over whether the existing box being used is of adequate size to begin with...
Your customer trusts that you know what you are doing, which may have to include upgrading the "perfectly good switchbox" that is in place now for one that is the proper size needed to accommodate safely connecting the two types of wiring using currently approved methods...
~ Evan
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On 4/5/2010 2:59 PM Evan spake thus:

Except that a new box is *totally unnecessary*, as Ideal 65 wirenuts are approved and perfectly suitable for the need here (AL/CU connections) and don't take up enough space to warrant a new box. Why are you assuming that I need to use the bulky connector suggested by someone else here?
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On Mon, 05 Apr 2010 16:01:39 -0700, David Nebenzahl

May be I should not poke my nose in here but I googled on Ideal 65 wirenuts and found some bad comments. " Senior Member           Join Date: Jul 2006 Location: Maryland Posts: 229 Default ashtrak,
Please, please, please, do not do this job. You obvioulsy have a lot to learn.
First of all, the purple wire nut method has been proven to be as dangerous if not more than the original wiring. This is because the compound inside the wire nut is flammable. Those wire nuts are for TEMPORARY repairs only!
Secondly, EVERY termination in the home should be repaired. If you leave one termination unrepaired, you have not resolved the problem with the aluminum wiring in the home. That could be the one termination that fails. So this now includes all recepts, lights, switches, dishwasher, disposal, water heater, A/C unit, range hood fan, recessed lighting, junction boxes in the attic, and all other terminations.
Thirdly, aluminum wiring is very delicate. If you haven't worked with it before, you must take great care in both stripping and splicing the wire. Even a small knick in the wire may be a point for future failure.
Fourthly, I imagine that you will be attempting this without a permit and given the information above, you will be putting the homeowner and yourself at a great liability if your "repairs" were to fail. Someone could be seriously injured or killed, then if you are lucky, only a lawyer (not a city prosecutor) will be showing up at your door to tell you all what you did wrong.
Lastly, well I won't even get into your pricing strategy.
Please think again about this repair. Let a professional that is experienced in the repair of aluminum wiring upgrade this home.
just passing it along email response not expected but to respond remove .uk at end TIA Hank
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wrote:

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On 4/6/2010 8:15 AM Hank spake thus:

[snip report]
Yes, I read similar comments on a site given as a link somewhere up-thread of this. The goop is flammable, as is the wirenut itself.
Rest easy. I didn't actually use an Ideal 65. I used an ordinary wirenut with Ox-Gard liberally applied (which is not flammable so far as I know).
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