Why does marine cable need to be tinned.

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mocruising

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Just wiring in a new auto pilot. The ordinary copper 6 mm2 cable was very reasonable then I tried the 6 mm2 marine stuff copper tinned I nearly spat out my dummy. Whats the advantage of tinned copper cable.
 
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Maplin do tinned cable. alot cheaper there than in the swindlries.

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Do you have a link, I have searched their site and even been to their store in the past, cant find any and the spotty faced kid looked at me like I was from another planet.
Thanks for any help here.
Also when ordinary cable goes black does the resistance start to rise in the cable? as if its just a problem to solder how often would this be needed anyway
 
When the copper goes black it's the surface oxidising, so apart from gradually thinning the conductor and being difficult to solder, they will make poor mechanical joints i.e. into screw terminals and crimps. The hardest one I found to source was battery cables, and they will thin to the point of giving way in a few years.
 
Copper wires, brass terminals, steel screws, electricity, salt water. Every connector becomes a battery in its own right. Corrosion runs riot, the cable ends drop off at the terminals. Any sea water creeping into the cable will corrode it inside the insulation, where you can't see it. Electrickery goes in, but none comes out, yet cable "looks" fine.

Tinned cables reduce all these problems. If you ever wondered why your boat power systems never work properly, it will probably be due to non-tinned conductors. Solder contains Tin & Lead, both of which are virtually non-reactive (hence tin cans & lead coffins for long term preservation of said container contents).
 
Well worth it if you can afford it, I can,t, sadly, but it is MUCH more corrosion resistant in a salt water environment. Very good advise already, more knowledgable than mine!
 
Tinned cable is great. But, if you are stuck or don't want to pay, I sprayed bare plain copper cable ends screwed into a terminal block on the underneath of a trailer 20 years ago with either Supertrol or Dinitrol, the wax anti-rust stuff for cars, and the connections have never failed despite being out in rain and salt and covered with road dirt.
 
Generally speaking this negative corrosion usually occurs on DC systems. Tinning was ommitted from most cables due to the tin market going throgh the roof in the 1960s (If I recall correctly) leaving only specialist uses for the tinned variety. seems to affect low voltage systems more then 110v and 220v plants. Hope that this is of uses.
 
Evadne said:
When the copper goes black it's the surface oxidising, so apart from gradually thinning the conductor and being difficult to solder, they will make poor mechanical joints i.e. into screw terminals and crimps.
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... and if I remember correctly most of the conducting along a wire occurs on the surface - hence the detrimental effect of oxidisation on the conductor.

If you aren't able to manage tinned conductors then you probably ought to at least use good quality adhesive heat shrink over your terminals to reduce the risk of salt/moisture/etc. getting along under the insulator where it will cause "rot".

I have found here http://www.furneauxriddall.com/shop/index.html to be a reasonably priced supplier of many things electrical. Also very good service and prompt delivery. (No connection other than satisfied customer!)
 
if I remember correctly most of the conducting along a wire occurs on the surface - hence the detrimental effect of oxidisation on the conductor.
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I don't think that's true for 12VDC. I'm with you all the way if we're discussing RF wiring.
 
mocruising said:
Just wiring in a new auto pilot. The ordinary copper 6 mm2 cable was very reasonable then I tried the 6 mm2 marine stuff copper tinned I nearly spat out my dummy. Whats the advantage of tinned copper cable.
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Consider the auto pilot failing just when you need it on a single handed night sail and you'd wish you'd done the installation correctly.

Also consider the time and cost of re-wiring any major job in a few years time just because you didn't use tinned cable.
 
Use silicone spray

If you use untinned wires but spray the exposed copper generously with a silicone spray, the silicone will not only prevent the exposed copper strands corroding, it will penetrate a long distance up the wire under the insulation (many metres) and the result will be, to all intents and purposes, as good as if you had used tinned wire. Suitable silicone sprays are sold by Comma, STP and others.
 
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