If the red and black are in the same cable, the Red is probably tinned copper. Some clues for you to use: Aluminum for NM cable is always 12 gauge or larger. A rare type is copper-coated aluminum, again 12 gauge or larger. To test for that or tinned copper, scrape the conductor to see if copper or aluminum appears after scraping.

thank you so very much. This helps alot and I will check to see if this is tinned Cu.

I will physically be going over to see what is going on tonight and try to trace to see how many wires are coming in and out.

I would suspect that that knot of white wires in the back of the box are neutrals. The switch that's there appear to be a three-way that's only being used as a regular switch (nothing connected to the third screw).

If that red wire is aluminum not only is there a question as to whether the switch is approved for Al connections, but if that black wire is a pig tail from the yellow wirenut on the bottom of the box in the picture, that's not an allowable way of splicing aluminum to copper either.

The WEMO has tinned copper fixture wires coming out it. You can not use wire nuts to joint these to aluminum either.

As best I recall, the use of AL NM cable was greatest about 1974. Was this house built in that general time frame?

That box and cable are definitely from 1947 or (most likely) later. The insulation on the individual conductors is indicative of that.

This post was edited by bus_driver on Sun, Sep 14, 14 at 16:18

Yea,I think hands on is the only way you will ever know. Isn't that a black wire on screw under the red?

klem-
I just noticed that illegal pair of wires under the middle screw, too. And that box looks too small to me to satisfy the box fill requirements with so many wires.

Also the mixture of what appears to be 12 and 14 g wires on the same circuit is suspect as well. Either it's a sign that we're mixing Al and Cu wiring inappropriately, or we're potentially got the wrong circuit breaker on this circuit.

thanks everyone, and I am sorry I have no feedback at this time. We just haven't been able to find a time to review this.

I hear your message loud and clear... and I was worried something sketchy was going on.

-I will check to see if it could be tinned Cu wire ?
-And if there are two wires under the middle wire (I was worried but wondered if it could be an illusion)
-And what is under the yellow wirenut.

If there is anything weird, we will take a few more light switches to check if this is repeated. The house is old enough to be have al wiring. And who knows what was done by further renovations.

thank you for the information about the Wemo. It's helpufl to know to stay away from it until I can figure this out .

Ronnatalie, may I ask one other baby question?

How could you tell that there are different gauges of wire?

Just by looking at it? What clues are there?

thanks, Margaret

Just wanted to say thank you for everyone's advice. According to the home inspection, there was Copper and Aluminum wiring noted.

There were two wires under the middle screw (copper and Al)

The inferior hot/source copper wire is pigtailed from the yellow wire nut where three copper wires are marretted to the Aluminum wire.

At this point, my friend is going to get more experienced people to come evaluate whether the switches, receptables and fixtures are attached properly.

thanks!

I am no expert, but I know the yellow marrette on the bottom is not listed for aluminum wiring. The Marrette 63 and Marrette 65 are, according to the writing on the packaging, approved for aluminum to aluminum and copper to aluminum connections. In addition, you want to use switches and receptacles marked co/alr.

I don't know if that's a sign that they work fine, or if my parents were just extremely lucky, but they bought their house in 1971 and it was built using aluminum wiring throughout. All connections were made using Marrette 63 and Marrette 65, without using Penetrox or the like, and they never had an issue. I did a fair amount of electrical work like installing/replacing fixtures and changing switches and receptacles, even adding outlets, and I know how to recognize signs of arcing. I am not endorsing the product, just curious what the experts here think of them as a solution for the OP.

The original Scotchlok Y, R, G and B wirenuts were listed for aluminum, but that listing for aluminum was later withdrawn. While the listing was in effect, I did use some on aluminum and am not aware of any of those that ever failed. With any such product, it is important to read and know the instructions and to follow those instructions.
Who reads the instructions on those packages?

As pointed out (by both me and wolley, the yellow wire nuts are NOT now (nor EVER) have been legal for aluminum.

Get a professional electrician, particularly one skilled in dealing with aluminum branch circuits to come fix this.

There are "purple" wirenuts that will do in a pinch, but most people regard them as problematic as well. There are some professioanl tools/fittings that will permaently join a copper pigtail to aluminum but by the time you get around to doing that you might inquire as to how much replacing the branch circuits are going to be.

Two wires under that screw is improper no matter what the wires are made out of.

Looks like the Marrette 63 & 65 are approved for AL and AL/CU connections in Canada where the OP and w0lley32 are both located

The connectors in that picture are not 63 or 65 either. Those would be BROWN not Yellow. I stand by my opinion on BROWN MARRETTES as I do for purple wirenuts. They are not a reasonable solution even if they are technically permitted.

I never said the ones in the picture were 63s or 65s, and I never said they were a good idea. I simply noted that in Canada the 63s and 65s would be compliant as w0lley32 asked about them. As far as opinion, here is mine: the only work I will do on aluminum branch circuit wiring 10 gauge and smaller is replace it. I have stood by that policy for many years and I don't miss the work or the liability that comes with it one bit.

This post was edited by joefixit2 on Mon, Sep 22, 14 at 19:20