Cy Jervis

I've been researching on the forum about speaker wire for a house under construction and came across a link to this article about speaker wire http://home.earthlink.net/~rogerr7/wire.htm .

I noticed at the bottom a problem that was noted with the Home Depo wire corroding after 6 months and had a picture showing the clear cased wire was turning green. I happened to have some in my garage as well left over from a project at my father's house a few months ago and decided to check it out for myself. The wire had been in my garage and when I went to look I found that the wire was indeed starting to turn green with, some spots worse than others, all the way thru the cable. My first thought was that perhaps it was a reflection and my mind playing tricks on me so I cut off a peice in the middle and stripped the end. The wire was starting to corrode and the cover was turning green. I have since checked the wire at my father's and found the same problem in the attic portion of the wire, while the rest of the wire in the house was fine. Has anyone else had this problem? Is this only seen because the cover is clear, or do other wires have the same problem? I was trying to convince myself that I don't need expensive cables but this has me spooked about skimping because I only have one shot to wire the house while it is under construction and don't want to have to rewire.

Rick_Brown

I don't think you should be using this kind of wire at all if your wire is going into walls and attics. You should use speaker wire that is encased in a fire-rated jacket. Unfortunately, this will cost you more.

Cy Jervis

It was listed as cl-2 on the spool which is in wall.

Chu Gai

This has been covered before. The green color is due to the formation of copper chloride salts. The chloride comes from the PVC (poly vinyl chloride) either from unreacted monomer (vinyl chloride) or from the degradation of the PVC. The extent of degradation of PVC is due to a variety of factors...
1) nature of the plasticizer (the stuff that makes it soft and flexible
2) the amount of plasticizer
3) the type and amount of any other inhibitors (this may include colorants)
4) temperature
5) humidity
6) light
7) etc.

The formation of the copper chloride is a surface phenomenon that only goes down a few microns and doesn't affect the sound. In any product from any source that uses PVC what you've observed will occur. Alternatives would be to use an insulator made of polyethylene, polypropylene, teflon, kynar, etc. Note though that copper is a fairly reactive metal and the other insulators can have varying degrees of permeability to the atmosphere (gases can diffuse through the plastic) so that various atmospheric pollutants that may exist such as sulfides can also cause surface reactions.
Of course, if you use colored PVC or opaque varieties, it's a bit harder to see.