Is this wire aluminum?

Reply

  #1  
Old 01-02-06, 09:19 PM
J
Member
Thread Starter
Join Date: Jun 2005
Location: United States
Posts: 72
Received 0 Votes on 0 Posts
Is this wire aluminum?

I was replacing a light switch today for a friend in an old home. When I removed the light switch, and started to put the new one on, I noticed that the wires looked "sort-of" silver-ish in color. Having read that aluminum wire is a really big deal requiring special connectors and switches, I became immediately concerned because I didn't know if this was aluminum wire or not.

The wires entering the electrical box appear to be the older cloth-covered NM without ground. Each conductor is covered with a fabric/cloth insulating material. The actual metal conductor (where it sticks out of the insulating material) looked copper in some places and "silvery" in other places. Streaks of copper color show through the silvery color where the screw, or plyers, or who knows whatever else have applied pressure to the conductor.

Being curious, I cut off a small bit of wire from the end of one of the conductors. It almost looks like some kind of silvery coating either built up or was brushed on the outside of a solid copper wire.

My research thus far suggests that aluminum wire is either solid or an aluminum center coated in copper... not a copper center coated in aluminum. My research also suggests that they didn't make aluminum wire in the cloth-covered NM without ground format.

The silvery-looking outside of the wire doesn't wipe off, but it can be scraped off . (I didn't want to do too much damage so I didn't try a lot of things on the wire.)

Can someone tell me if this wire could be a potential aluminum problem? I thought copper oxidized green... Can old copper wires corrode in a silvery color instead of green?
 
  #2  
Old 01-02-06, 09:27 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Look at a cut end of one of the wires and see what color is the center core of the wire. That's the primary wire type. It could be copper-clad aluminum (which is aluminum wire that looks like copper from the outside), or tinned copper (which is copper wire that looks like aluminum from the outside).

If the core of the wire is aluminum, you should be concerned. If so, I recommend you not touch any wiring in this house, and neither should your friend.

The probability of aluminum wire can be directly traced to the year the house was built. Do you know what year that was?
 
  #3  
Old 01-02-06, 11:04 PM
Andrew's Avatar
Member
Join Date: Apr 2003
Location: USA
Posts: 1,017
Received 14 Votes on 10 Posts
What you've got is tinned copper wiring. This was common in the old fabric covered wires to aid in the soldering of connections.
 
  #4  
Old 01-03-06, 03:05 PM
J
Member
Thread Starter
Join Date: Jun 2005
Location: United States
Posts: 72
Received 0 Votes on 0 Posts
I don't know when the house was built, but it is very old and has pipes for gas lamps in many rooms, knob and tube wiring, cloth-covered NM, and modern NM-B depending upon where you look.

The core of the wire in question is copper. Tinned copper sounds right.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: