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post #1 of 5 Old 12-20-2012 Thread Starter
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Connecting 120V receptacles

As I understand it, the proper way to wire up a 120V receptacle is to use locking fork terminals on the side wire screws. As opposed to back-wiring or bending the wire into a hook and screwing it down directly, as done in residential wiring.

I want to chain a second receptacle off an existing GFCI. Connecting new wiring to the feed screws on the GFCI with locking forks is no problem for the hot and neutral connections. The problem is with the ground. There is just one ground screw and there is no way to connect two locking forks to it. At least nothing that looks like it would be acceptable.

If this were residential wiring, what would be done is to connect to two grounds with the short jumper wire in a wirenut, then connect the jumper to the receptacle ground screw. But wirenuts don't seem like such a good idea on a boat, since they aren't sealed.

So what's the marine wiring best practice for this? Use a three-way butt splice? Try to jam two terminals onto the ground screw?
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post #2 of 5 Old 12-20-2012
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Re: Connecting 120V receptacles

Make up the jumper, solder the splice and run a silicone filled wire nut onto it. If yer real anal; wrap with self-sealing tape. You *are* putting it into a box and not exposed...right???
I'd shy away from tap connectors. Less contact area and messy-er to seal.
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post #3 of 5 Old 12-21-2012
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Re: Connecting 120V receptacles

The best reference I've found is Boatowner's Illustrated Handbook of Wiring by Charlie Wing. This includes the ABYC standards. If you don't follow the standards you risk a problem if you have an insurance claim or have a pre-sale survey done. Solder can't be the sole means of connection support you need a mechanical connection as well. Splice, butt, friction blade or bullet snap, terminals. You can stack up to four connectors per screw, and it seems without looking at it that would work if you have enough screw length, which you may not have.
If not there are three-way crimp butt splices, but I haven't used one. Wire nuts aren't allowed. I had a number of ground wires and made up a connection block to screw several wires to then has a wire going to the AC source Shore Power connector receptical. Except at the power source you can't have a connection between the neutral and grounding terminals if that's your set-u[. Should be in a waterproof enclosure, , screw and connector the same size, drip/tension relief loop.

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Kingston WA
Puget Sound
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post #4 of 5 Old 12-21-2012
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Re: Connecting 120V receptacles

And since nobody has mentioned it yet, crimp-on terminals are to be used with stranded wire ONLY.

FWIW, most of the bad connections I've seen, in both line voltage and secondary/control voltage circuits have been at crimp-on terminals. These usually appear to have done by the lightweight crimping notches on a pair of wire stippers. If you're using crimp-on terminals and want the connection to last, and be safe and reliable, use a heavy-duty dedicated crimper (Sta Kon, Klein, e.g.)
(Klein shown)
I have a pair of Sta Kon crimpers that belonged to my grandfather, well over 60 years old, still work great.

s/v My Sweet Girl!
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Last edited by Brewgyver; 12-21-2012 at 09:41 PM. Reason: link to example
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post #5 of 5 Old 12-22-2012 Thread Starter
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Re: Connecting 120V receptacles

The problem with trying to attach two terminals to the same screw is that that each screw is inside a recessed area on the receptacle. It's probably a safety feature that the hot screws don't stick out the sides. But this means that you can't orient the two terminals at 90 degrees to each other. They have to be one on top of the other, so that the barrels of the terminals will hit.

It seems like there must be a standard way of doing this in new boats. They can't wire every single receptacle with a dedicated wire run. That's just way too much 12/3 wire to be cost effective. The receptacle I'm using are supposed to be "marine". As far as I can tell this means they accept locking spade terminals, which a lot of receptacle won't fit. I haven't seen any that have two ground screws, which would certainly be very helpful.

I am using boxes of course. Standard residential old-work boxes, since I couldn't find any "marine" boxes that cost 10x as much with picture of a boat on them. There are fiberglass heavy duty boxes, but they have a lot more non-stainless metal on them so I figured they probably weren't better for boat use.
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