Outlet wire runs 14/3 vs 12/3

[Edelweiss]

When our marina installed new docks a couple of years ago, they did it up right with modern 30 / 50 amp weather protected pedestals and separate water supply for each slip. With power distribution handled from sub stations out on the docks, voltage runs at a solid 120v year round.

The old docks varied anywhere from 105V to 115V mainly in the winter and when it rained, it wasn't uncommon to see steam rolling off a hot unprotected box. You could expect to go through a power cord dock end plug and socket every year.

No more. . . . life is good

 

[what_barnacles]

Yes, you may have lower voltage at the last slip in a marina but you can't raise it up by using larger wire in your boat.

The reason for using larger wire with lower voltages is for compressors. They pull more current at lower voltages. Thus larger wires gets lower voltage drops lower current rise and lower wire temp.

 

[Wxx3]

I'm not saying you're wrong, but I don't believe you are right. In residential wiring, the length of a run is generally based only on the current, not the length. All the conductors feeding receptacles will be #12 regardless of the length. We're not talking about docks or outbuildings, but a house, for example. The run to an outlet on the far side of a house from the panel could easily exceed 100'. The concern for voltage drop is much less at 120 volts than at 12 volts.

That said, like so often happens, much more is being made of this project than needs to be made. #14 for 15 amp, #12 for 20 amp. 20 amp is better. That's all he needs to know.

And I would really run the larger cable, you will not regret it.

 

[FF]

you can't raise it up by using larger wire in your boat.

TRUE!

However the less voltage drop , from the dock or inside in your boat the better.

Remember a motor starting (LRC) amperage can be 300% of the run amps , so the rotten voltage is magnified by 3 times.

Makes one want to discard the thermostat and run the air cond 100% of the time !

A good V meter like a Fluke will record the lowest voltage (or highest) and can make interesting viewing.

 

[winty]

Update. Solid core wire runs removed and replaced. Everyone's advice followed, 12/3. The outlet breaker is 15 amp.

I thought the new wire runs would be a nightmare and swapping duplex outlets to GFCI outlets easy. The process was the opposite. The factory wooden duplex boxes had to be chiseled larger, which took hours. One box split but was salvaged with epoxy.

I will post some pictures tomorrow once the sun is up.

Thank you all.

 

[psneeld]

Update. Solid core wire runs removed and replaced. Everyone's advice followed, 12/3. The outlet breaker is 15 amp.

I thought the new wire runs would be a nightmare and swapping duplex outlets to GFCI outlets easy. The process was the opposite. The factory wooden duplex boxes had to be chiseled larger, which took hours. One box split but was salvaged with epoxy.

I will post some pictures tomorrow once the sun is up.

Thank you all.

And that is exactly why I ran 14/3 to some of those idiotic teak outlet boxes...no room inside and the 12/3 is difficult to jam in there.

Appliances and certain outlets all get their own oversized circuit and breaker anyway...so voltage drop to important components isn't an issue. Manufacturer wiring in older trawlers can be insane. My entire boat collection of outlets was on ONE 20 amp breaker. Now I have seven circuits, six 15 amp, one 20 amp. Plus the separate circuits for appliances that draw near 15 all the time or have buried outlets. Even some of the 15 amp circuits have 12/2 to the first outlet in that circuit.

For the circuits most likely to see 15 or more amps continuously, I went with the larger dual outlet boxes and painted them white to match the walls. Made the wire runs easier in some cases as I just used conduit instead of the totally insane tiny routed channel behind the teak vener.