Black wire?

[Dave Neptune]

I have a question for you electrical experts, probably Neil can answer this but I thought it would be good to ask on the forum instead on the phone.
What is black wire caused by on the ground side of a 12v system. I have never really understood what it really is or the cause. I believe it increases resistance but that is about all I know about it and I'm not sure of that. I have seen a bit on my boats 40+ year old wiring. I have replaced a bit of wiring when the pig tails left after replaceing something electrical are to short to tie into. The wiring leaves a bit to be desired on most old production boats like mine.

Dave Neptune

[joe_db]

Do you mean black corrosion on the copper?
I had to rewire my whole boat because of that. I always assumed it was too much salt air combined with C&C not using tinned wire. It eventually turns the wire into black powder. I have never ever seen Ancor tinned wire do this

Originally Posted by Dave Neptune

I have a question for you electrical experts, probably Neil can answer this but I thought it would be good to ask on the forum instead on the phone.
What is black wire caused by on the ground side of a 12v system. I have never really understood what it really is or the cause. I believe it increases resistance but that is about all I know about it and I'm not sure of that. I have seen a bit on my boats 40+ year old wiring. I have replaced a bit of wiring when the pig tails left after replaceing something electrical are to short to tie into. The wiring leaves a bit to be desired on most old production boats like mine.

Dave Neptune

[ndutton]

Joe is on the money. It actually has more to do with moisture than salt but salt certainly aggravates the situation. The condition is worse at the ends where the stranding is exposed. Over time it will migrate up the stranding. The result is higher resistance of the wire.

This is common in landscape lighting wire too.

[Dave Neptune]

Thanx Neil & Joe, will tinned wire eleiminate the problem? Or what about sealing up the ends.
I have been told by a few to use aircraft wire when rewiring as it's insulation is much tougher for pulling wire in a fiberglass boat. Sounds like a good idea if so. However is aircraft wire better against "black wire" or is it to tinned?

Dave Neptune

[JOHN COOKSON]

I use marine grade wire on the boat with the end terminals soldered and heat shrunk. It's worked well over the years. The heat shrink keeps the moisture away.

TRUE GRIT

[Marian Claire]

Good time to ask this question. During Irene all the boat boxes at the marina got flooded. I had several partial rolls of wire, from the PO, in a tub in my box. They sat in the brackish water for a few weeks before I cleaned out my box. Bad mistake on my part. Is the wire toast? Can I check and see how far the water worked up the wire and maybe save some? Dan S/V Marian Claire

[JOHN COOKSON]

Probably the best bet is to unroll it and dry it out then put it in a bag with a few desiccant packs. Don't know how much it is worth to you to fool around with it but I do know marine grade wire is not inexpensive.

TRUE GRIT

[edwardc]

If it's tinned wire, it's probably ok. If not, cut it back an inch, strip it, and check for greenish or black corrosion. If found, keep cutting back until you get to clean dry copper.

If you decide to get rid of it, take it to a copper recycler. They pay good money for scrap copper. It's not gold, but it's getting there!

[Marian Claire]

Thanks guys. Will do. Dan S/V Marian Claire