Connecting aluminum electrical wire to copper wire

[Stephen Tashiro]

Is it good practice to connect aluminum electrical wire to copper electrical wire with a wire nut ? - no problem with unlike metals?

I need to replace an electrical outlet in a house that has grey/silver colored wires, which I assume are aluminum. My understanding is that all ground wires should be connected together with a wire nut, with only one wire leading to the ground terminal on the receptacle. Must I use aluminum wire for all the ground wires? Or can the short length of wire that leads from the wire nut to the ground terminal be copper ?

[Rod Sheridan]

Hi, you can either use a receptacle rated for Cu/Al or a special wire nut with joint compound in it, both available from your local electrical supplier........Rod.

[John Lanciani]

Burned Purple (Ideal #65) Wirenuts found in the field
CAUTION: Many electricians, who are not COPALUM certified, recommend other repair methods. While these repair methods are less expensive than COPALUM crimp connectors, we agree with the CPSC that these repairs are considered unacceptable and "does not solve the problem of overheating present in aluminum branch circuits."
�Pigtailing with the Purples�
The most often suggested unacceptable repair; ("pigtailing") involves attaching a short piece of copper wire to the aluminum wire with a twist-on connector sometimes called a wire nut (IDEAL Purple #65); the copper wire is connected to the switch, wall outlet or other termination device. The Commission staff has evaluated the effectiveness of "pigtailing" as a repair. In CPSC-sponsored laboratory testing, some brands of twist-on connectors have performed very poorly. Accordingly, from what we have seen in the field, we agree with the Commission staff and can validate the laboratory testing in believing that this method of repair does not solve the problem of overheating present in aluminum branch circuits.
At best we consider the proper application of Purple Wirenuts a temporary repair. However, being that this wirenut is filled with a flammable oxide-inhibitor and the manufacturer has stated that this wirenut is NOT INTENDED FOR A COMPLETE HOME RETROFIT, (http://www.inspect-ny.com/aluminum/i65debat.htm (http://www.inspect-ny.com/aluminum/i65debat.htm)) we believe it is best to leave aluminum wiring alone until such a time as it can be permanently repaired via re-wiring or COPALUM crimping.


Above was lifted from the Mike Holt site; lots of good info there but the short of it is that connecting copper to aluminum with any of the available rated wire nuts is bad juju. Proceed with extreme caution...

[Matt Day]

Generally a bad idea I think - dissimilar metals can result in galvanic corrosion. There are some very smart electronicians who will likely chime in with more.

[Rollie Meyers]

Ideal Wingnuts®, & 3M Scotchlocks® used to have CU/CU, AL/CU, & AL/AL listings but that went away and are now for copper conductors only, the AMP Copalum system is only available to installers who lease the tool, the purple Wingnuts® are about the only option to pigtail copper to aluminum conductors, other then Copalum, but the purple connectors are for aluminum to copper connections only, not aluminum to aluminum, and can only be used once, remove them for any reason & they must be replaced, the best solution is to get rid of 10 & 12 AWG aluminum wiring but that is a very costly endeavor.

IMO, the Inspect NY website does seem to me as having their own agenda, but with all things on the internet one must be aware.

[Robert Engel]

I'm not an electrician but I know this can be a prlblem.

The feed that went to my shop was copper from the panel to a junction box, then aluminum run to the shop.
The wires were connected with a bug.

After about 10 years I lost the neutral. A different electrician came out and said that was a no no.

He used a connector similar to a bug that keeps the two wires separated. Can't remember the name of it.

[Rollie Meyers]

I'm not an electrician but I know this can be a prlblem.

The feed that went to my shop was copper from the panel to a junction box, then aluminum run to the shop.
The wires were connected with a bug.

After about 10 years I lost the neutral. A different electrician came out and said that was a no no.

He used a connector similar to a bug that keeps the two wires separated. Can't remember the name of it.

Split bolt.

[Rod Sheridan]

Split bolt.

Or Servit connector..................Regards, Rod.