Wire Gauge

[Redbeard33]

I have a chance to buy a whole spool of marine tinned wire at cost, what would be a good gauge for MOST applications (led lighting, stereo, running lights, navigation equip. etc) it is understoond that some equipment draws more and needs heavy gauge, but what is the most common?

[djmarchand]

Check your DC electrical panel and see what the most common breaker rating is. Usually 15 amp is the most common and 14 guage is good with that.

The point is the breaker protects the wire. It is (almost) irrelevant what the appliance draws.

David

[fairbank56]

Circuit voltage drop is just as much a concern as current handling capability in low voltage systems, so it is very relevant what the appliance draws. For example, a tri-color light at the top of a sailboat mast that requires 2 amps but with a cable run of say, 85', would require a size 10 gauge wire to meet ABYC requirements for voltage drop. So, as you can see, it depends on current requirements as well as length of cable run. I would say that 12 and 14 gauge are most common with 16 gauge being the minimum for general system wiring as per ABYC with some exceptions.

Eric

[fairbank56]

If that tri-color light were an LED fixture that draws less than 1/2 amp, you could use 16 gauge. The panel breaker does not have to be rated for the full current that the wire is capable of handling. For example, you might have a relatively short run of 14 gauge wire feeding your VHF radio but only use a 10 amp breaker or you might only have a 5 amp breaker on that 10 gauge wire circuit feeding your tri-color light.

Eric

[thinwater]

1. Only one wire size.
2. No color coding.

I think you may find this is not a great deal. Maybe it is better to get what you need, as you need it. Just maybe.

[sailvayu]

90% of most boats are wired with #14. I would get that if I were you. Just resist the temptation to use it when you really need something bigger like for bilge pumps and other motor loads. Best for lights and small electronics, and some small motors like shower sumps. Just do the math before running the wire. You could always buy the 12 and be over kill for most things.

Good luck

[speciald@ocens.]

If OI had to pick one - 12 g.

[Zednotzee]

Colour coding your wiring is a non-issue in my book. It's easy to get coloured tape or shrink tubing to mark the wires accordingly. Alternatively you could get stick on numbers, which are better than colour coding since they are unlikely to change into another number with age (unlike wire insulation- is that pink supposed to be red? Is that orange, or tan, or yellow?).
Finally, ABYC is purely voluntary, not some kind of law. 96% of the boats out there don't meet all ABYC standards, & that includes newly built boats from reputable manufacturers. (The ABYC is a good place to start though).

[Maine Sail]

Originally Posted by Redbeard33

I have a chance to buy a whole spool of marine tinned wire at cost, what would be a good gauge for MOST applications (led lighting, stereo, running lights, navigation equip. etc) it is understoond that some equipment draws more and needs heavy gauge, but what is the most common?

14 is probably most common but I'd buy the 12 if you can get it at cost. I always buy my wire in bulk and have many sizes in both AC and DC wire. I always size the wire based on load for each circuit and you'd be surprised how often you need 12Ga.

This was the wire consumed for just one re-wire on a 36 footer. A 100 foot spool does not go very far. Buy the 250 or 500 if you can and it will last...

[fairbank56]

Originally Posted by Zednotzee

Finally, ABYC is purely voluntary, not some kind of law. 96% of the boats out there don't meet all ABYC standards, & that includes newly built boats from reputable manufacturers. (The ABYC is a good place to start though).

ABYC standards are endorsed by the USCG and ABYC is partnered with the National Marine Manufacturers Association to implement the use of all ABYC standards in the NMMA boat and yacht certification program. Over 400 builders are involved in the NMMA certification program and those builders build 90% of boats on the water today. There are also federal standards which ARE laws in the code of federal regulations that cover all aspects of boats and associated equipment. A boat built to ABYC standards will meet the federal regulations. While the implementation of ABYC standards are voluntary, manufacturers are pretty much forced to, and do, comply.

Eric

[Zednotzee]

Originally Posted by fairbank56

ABYC standards are endorsed by the USCG and ABYC is partnered with the National Marine Manufacturers Association to implement the use of all ABYC standards in the NMMA boat and yacht certification program. Over 400 builders are involved in the NMMA certification program and those builders build 90% of boats on the water today. There are also federal standards which ARE laws in the code of federal regulations that cover all aspects of boats and associated equipment. A boat built to ABYC standards will meet the federal regulations. While the implementation of ABYC standards are voluntary, manufacturers are pretty much forced to, and do, comply.

Eric

Here are some examples of their "compliance":

Stoopid boat builder tricks

Note that in many cases, they say they build "using" ABYC standards, not "to" ABYC standards. This is the same as some helmet manufacturers, who affix a "DOT Tested" sticker- yes it was tested, & it failed!

[svcambria]

FWIW, I carry 100' of 10 gauge and 100' of 12 gauge, and different colors of electrician's tape to ID it as high or ground. Also somewhere in the bilge is a roll of 8 gauge, about 25', w/ green tape. For many applications the gauge is overkill, but voltage loss is less (sort of a passive conservation) and the appliance on the other end gets changed every few years, so I don't have to worry (much) about undersized wire.
When I rewired I went through 300' of 10G for mast wiring, 100' of 1G for the refrigerator and other big-time draws, and 150' of 0/2 for windlass, inverter, battery jumpers etc.

Michael

[fairbank56]

Originally Posted by Zednotzee

Here are some examples of their "compliance":

Stoopid boat builder tricks

So, I guess your point is that the do-it-yourselfer would be very foolish to not comply with well established standards. I agree. That's why I responded to djmarchand's partially incorrect advice. I suspect that he is aware of the voltage drop issue, but didn't elaborate. You must consider voltage drop as well as current requirements when selecting wire size.

Eric