Corroded anode wire

[poiu]

I found a few corroded wires where my ground wires attach to the hull anode. There are 7 wires going from the engine, generator, pumps etc. The wire is a multi strand 9 or 10 AWG. I pulled off the terminations, cut back a foot of wire, cleaned up the wire with sandpaper and attached new crimp connectors. The wire seems good in so far as it is flexible, doesn't crack and has lost very little material due to corrosion.

Now that I have done it I am not sure I have done the right thing. If these were carrying current I could measure how well the wires are working, but they are carrying tiny voltages and currents and I am not sure if the skin effect is important in this function, which may be affected by the corrosion. My wires have blackened surface and I don't know how far it goes. It is a huge job to replace as the wires are deeply buried and I hope I don't have to do it.

Here is a picture of a sample of a bit of wire before and after cleaning up.

Any advice?

[captain58sailin]

If you have the black, you are still corroded inside the insulation, you have to cut it back to where it is shiny, or better still replace the whole length.

[Andina Marie]

That wire is not marine grade. Each strand of marine grade wire is coated with Tin. Once the cancer starts you need to replace the whole length, the salt and moisture is still trapped inside the insulation and the cancer will continue to spread.

If you are referring to "bonding" wires between through hull fixtures, these are typically made with solid wire instead of stranded. Although they will still corrode, with only about 5% of the surface area of equivalent stranded wire they will last 20 times as long and being uninsulated they are able to dry out.

[poiu]

Originally Posted by Andina Marie

That wire is not marine grade. Each strand of marine grade wire is coated with Tin. Once the cancer starts you need to replace the whole length, the salt and moisture is still trapped inside the insulation and the cancer will continue to spread.

If you are referring to "bonding" wires between through hull fixtures, these are typically made with solid wire instead of stranded. Although they will still corrode, with only about 5% of the surface area of equivalent stranded wire they will last 20 times as long and being uninsulated they are able to dry out.

I am sure you are right about the ongoing deterioration, however the deterioration is very slow. I believe the corrosion started from a flood from an open window about 13 years ago under the previous owner, so it is progressing very slowly. I have made a good connection to bright copper, so I am hoping my connection will not deteriorate and there is enough copper left for the wire to work.

These wires are for earth bonding everything metal to the anode coming into contact with sea water except for through hulls. You are right, the wire is not tinned. Oyster don't use tinned wire. I don't know why so. I do know tinned wire can corrode badly too. Interesting that bonding wire is single core - a good sign that strands might not be important for the wire's function.

[senormechanico]

There is no skin effect factor in DC circuits, only RF frequencies.

[poiu]

Originally Posted by senormechanico

There is no skin effect factor in DC circuits, only RF frequencies.

I seem to remember the HiFi industry of yesteryear made something about thick mega strand cables transmitting acoustic signals better due to a skin effect. They cost a packet. I think that is where I got it from. Maybe it was a misapplication of the science.

[hellosailor]

Poui-
Do yourself a favor, put new, tinned, marine grade wire on the ToDo list. Or braided tinned ground strapping, which is even more corrosion proof and sometimes can be found (by the reel) for not much more. The ground braid is never insulated, shouldn't need to be.


With insulated copper wire, every time the temperature changes the air inside the wire/insulation expands and contracts, bringing in fresh moisture. Or it there is a pinhole or chafe anywhere in the wire, fresh moist air gets in there. So maybe you've found all the bad wire, maybe not.


Probably "good enough" but if you replace it all with something that just can't have that problem again? Right, one less problem. Troll eBay or the surplus houses, when you see better wire at a good price, get around to it.

[thinwater]

All true. Though CG approved, it is not the best in damp places. However, corroding through the wire is rare. But I agree that I would up-grade when time allowed. If you can use the old wire to pull the new wire, it may not be so bad.

As for the current, about 100-400mA maximum, depending on the number of zincs on the system. Generally much less than 100mA or the zincs will vanish fast. The only reason for 10ga is ruggedness and corrosion allowance.

And in the future, tinned or no, coat all connections with heavy grease (I did a 1-year salt spray chamber test for Practical Sailor--it really helps).

[poiu]

Originally Posted by thinwater

All true. Though CG approved, it is not the best in damp places. However, corroding through the wire is rare. But I agree that I would up-grade when time allowed. If you can use the old wire to pull the new wire, it may not be so bad.

As for the current, about 100-400mA maximum, depending on the number of zincs on the system. Generally much less than 100mA or the zincs will vanish fast. The only reason for 10ga is ruggedness and corrosion allowance.

And in the future, tinned or no, coat all connections with heavy grease (I did a 1-year salt spray chamber test for Practical Sailor--it really helps).

Is the current flowing a measure of how much galvanic activity there is? It is easy enough to put a meter in-line.

I realise the best advice as other have mentioned is to replace. The thing is, it is the opposite of a trivial job. The wire cost is irrelevant. The labour is the issue. The wires are so deeply buried I will only dig them out if I really, really have to.

[hellosailor]

" The wires are so deeply buried I will only dig them out if I really, really have to. "
It isn't "proper", but that's the reason why many folks would simply cut the ends of the old wires, cap them, and run new wires in parallel to them.
Or rather, run the new wires, and then cut & cap the old ones.(G)

[HKTim]

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[bizzy]

To clean the wire use a mixture of vinegar and salt ,dipp it in for 10 minutes and it will be good as new for connecting again.