wire size from battery to key switch

[ekenna]

I noticed last saturday that the wire from the 1/2/all switch to the key switch has the insulation worn off. I electrical taped it so I could do the test I needed but I need to replace it before the boat goes in the water. I could not find a wire size number on it. Besides the cables that go to the battery switch and starter this wire is the thickest wire on the boat. Is there a recommended size?

[sailingdog]

The wire size is largely dependent on the distance the wire needs to run and the total amperage it needs to support. Without more information, it is hard to say. Why not remove it and take it to the store to compare the wire sizes. The lugs may also be stamped with the size of the wire.

[mitiempo]

It shouldn't have to be very large gauge as it doesn't carry much amperage. The heavier wires should be from batteries to switch, battery to starter and from alternator to batteries or switch depending how the system is configured. The wire to the key switch is powering only the instrument panel and the power to the start solenoid. If it is fairly close probably 10awg.

[tommays]

Well

A wire dirrectly from the battery switch to the key switch without a fuse or breaker just sounds like a problem in it self

[mitiempo]

True it should be fused or use a breaker as all wires (except possibly the starter itself) should. But it is not a high amperage carrying wire.

[Waltthesalt]

If you bring the wire to the boat store they'll have a gage to measure it. If you know the approximate current you can look at the table in the West Marine or Blue Seas on-line catalog as to the gage

[tommays]

It sounds like the smoke was let out of this wire at some point due to seme type of short

[ekenna]

mitiempo you are correct in that this powers the following instrument panel, the starter solenoid, the glow plugs(through another switch), and the alternator "trickle". As far as wire length it should be less than 10 feet (the battery switch is in the port locker and the switch is on the staboard side of the cockpit. As far as amperage I have no clue. I guess taking it off and to the store is the safest option. I was hoping to be able to get it on the way down to the boat in stead of having to go to the boat and making a trip back out to the store. Tommays you have a good point.

[arf145]

It would help if you had measured the diameter--here's some approximations for AWG:

.312" = #8
.22" = #10
.16" = #12
.14" = #14

[hellosailor]

Obviously whatever the old wire was, the boat got along with using it. BUT since the insulation has broken down, it is also very likely that wire was not sufficient or safe for that run. It could have broken down from outside heat (wire is rated for engine spaces and chemicals, or not) or internal heat, i.e. being too thin for the load and degrading over time.

If you have an ammeter, even a 10A ammeter in a $20 multimeter, you can test the wire to see what load it really is carrying. Or sum up whatever it is attached to. And also look to see if those circuits are fused on "the other end" so to speak.

If not...personally I would replace it with properly rated tinned wire (for engine spaces) and upsize it by one or two gauges "just in case".