Actually the CPSC doesn't recommend CO/ALR devices either. They only recommend the COPALUM connection by Tyco or AlumiConn connector by King Industries. And, of course, a complete copper rewire. Purple wire nuts (or any kind of twist connection), CO/ALR devices, and other crimp connectors should only be used for temporary repairs. Read CPSC report here.

Thanks Mike, that's a great article. However, you'll notice the Twist-On section is strongly worded and mentions multiple sources.

The "CO/ALR" section mentions one set of tests. That's an overabundance of caution that has more to do with lawyers than science.

The purple wire nuts (Ideal #65) have been on the market for quite a while and are UL approved. You'd think that if there was such a great risk, that Ideal's lawyers would have pulled the product long ago.

Ideal's compliance doc:

October 18, 2000

The IDEAL Model #65 TWISTERî AL/CU Wire Connector, when used in accordance with the instructions included with the product provides a safe, effective, legal, and permanent solution to the problem of connecting copper conductors to existing aluminum branch circuit wiring.

The IDEAL Model #65 TWISTERî AL/CU Connector complies with the N.E.C. Section 110-14b for aluminum to copper connections, and Federal Specification W-S- 610E, is UL 486C Listed, UL 467 Listed, UL 94V-2 flame rated, CSA C22.2 #188 Certified, and rated 105âÂÂCâ (221âÂÂFâÂÂ) for use in all branch circuit and fixture splicing applications.

These approvals have been in full-uninterrupted force since the day the connector was introduced and remain intact today. For further information please contact IDEAL INDUSTRIES INC. at 1-800-435-0705.

They are listed, and hence are legal in most places. However the CPSC doesn't like them, but doesn't have the regulatory authority (yet) to make them illegal to use.

Here is the CPSC statement on Al wiring.

Here is a link that might be useful: www.cpsc.gov/cpscpub/pubs/516.pdf

Mike_kaiser "The purple wire nuts (Ideal #65) have been on the market for quite a while and are UL approved. You'd think that if there was such a great risk, that Ideal's lawyers would have pulled the product long ago."

The Ideal #65 twisters are rated for al to cu connections ONLY (see attached link). Not for al to al connections. So, unles you only have one aluminum NM cable in each box they are not rated for your application. Just because people use them on al to al connections, against their listing, doesn't mean they are safe.

Here is a link that might be useful: UL listing for Ideal wire nuts

The devil is in the details. Thanks for pointing that out btharmy! So the problem isn't with the product, it's the people not using the product correctly.

Without referencing any regulations of these various organizations, the problem is fairly simple with mixing aluminum and copper.

The thermal dynamics of copper and aluminum wiring are different and the heating and cooling cycles caused by current flow lead to breakdown of their conduction and create resistance between them.

Then, there is galvanic corrosion between the two dissimilar conductors, which causes resistance and heat.

Also, aluminum oxidizes much easier than copper and creates added resistance.

But to say that the Ideal #65 connectors can only be used for AL/CU, and not AL/AL, (by UL or whoever) has absolutely no scientific merit.

Twisting two aluminum wires together, and including an anti-oxident paste (for possible AL oxidation), will not be any less safe than twisting two copper wires together.

Twisting two copper wires together is also NOT AN ALLOWED method of making a connection. The wire nut does not use the "twisting" as the basis of the connection, but rather the pressure that the threaded part of the nut puts on the connection.

BTharmey's statement isn't quite complete. While AL-to-AL by itself is not one of the listed combinations, you can mix 3 #12 or #14 wires as long as at least one is Al and one is Cu, which should cover most pigtailling circumstances (two incoming Al branch circuit wires and one copper pigtail to the fixture).

Ron, I have a great deal of respect of your knowledge and your postings, but I guess I'm missing something here.

The twisting is a result of the wire nut application and the pressure being applied to the two wires that creates a more evenly distributed area of conduction between the two helix coiled wires.

But then, by "twisting", I was only referring to what you do to your nuts.

The twisting of the wires is irrelevant to making the gas tight connection. The instructions for the wire nuts don't require twisting the wires either prior or during the process of applying the nut. Yes, the twisting of the nut is what applies the pressure to make the gas tight connection. It is not the nut squeezing the wires together that makes the connection, it is the pressure applied to the conductor by the conductive inside of the nut. That coupled with in this case the anti-oxidizing goo that's inside the nut.

Let's talk about your circuit breaker box. Many of these homes with aluminum wiring also have Federal Pacific panels which could very well be at the root of your problem. IMO, aluminum wiring is not a big problem if it is properly terminated and the proper fixtures used. FP panels are very dangerous and have been responsible for many fires.