Question on Wiring 12V Fuse Block with Negative Bus - Fiberglass RV

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Old 03-05-2015, 01:20 PM   #1
Name: Ben
Trailer: Triple E
Posts: 59
Question on Wiring 12V Fuse Block with Negative Bus

Hello All,

I have a Surfside trailer that I recently gutted/rebuilt. The original wiring in it was an absolute mess, so I tore it out during demo, along with the dilapidated/rotten furniture/cabinets.

At the moment, my electrical needs are served by a Goal Zero Yeti 400 power pack, which gives me access to a couple of AC power outlets and USB charging. I have a portable 100 watt solar panel that goes along with it, as we primarily dry camp. Yes, these things are stupidly expensive for what they are, but I have access to employee pricing on them and already had one in my possession prior to acquiring the camper.

My question is this: I'd like to add back a few 12V circuits in order to add some LED lights and a porch light, as well as power a fantastic fan and add a couple of small computer fans to the back of the fridge compartment to aid in cooling efficiency. I've spoken with Goal Zero and they offer an adapter (pictured below) that can be connected to their proprietary 6mm 12v ports on the power pack. These ports only push 10A/120W, but my needs are minimal and fit within that scope. My thought is that I'll use the Goal Zero Adapter and connect it to a Blue Sea St Blade Fuse Block.

Wiring to the lights/accessories is easy enough, but I have a couple of questions regarding installation of the fuse block.

1. Does the negative bus serve in place of grounding to the frame, or does the bus itself need to be grounded to the trailer frame?
2. Should the negative adapter wire be connected to the bus or should it be grounded to the frame along with the bus (assuming the bus needs to be grounded to the frame?)
3. Anything I'm missing here?

Thanks in advance for any input.


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Old 03-05-2015, 07:33 PM   #2
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Name: Charlie Y
Trailer: Escape 21 - Felicity
Posts: 1,332
My preference would be to run two-conductor wire over to your 12V application, not depend on the frame for grounding. In a fiberglass trailer the frame might be a long ways from where your light is located. Do a local ground buss (if not part of your distribution block.)

Charlie Y

Don't drill holes, try custom storage you design:
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Old 03-06-2015, 12:36 PM   #3
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Name: Darwin
Trailer: 2002 19 ft Scamp 19 ft 5th Wheel
Posts: 3,085
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What does your camper schmetacs show concerning the ground to the frame. All schmetacs I have seen including cars show the negative to the frame. I don't think you can go wrong with what has been around all these years.
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Old 03-06-2015, 03:20 PM   #4
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Name: Tim
Trailer: '88 Scamp 16, layout 4
North Florida
Posts: 1,487
Ground the negative bus to the frame, ground all your circuits to the bus. Of course, I know you know this but; use a good wire, good connectors, and make a good clean connection to the frame. I am doing something similiar in a slow motion re-wire of my Scamp and am using 12-2 for all my circuit wiring even though it is probably electrically way big. It is not however mechanically too big if you understand my meaning. It is certainly large for the amperages it will carry but I did not want any bending and breaking over the years of rattling down the road. I am doing this once and done if you get my drift.
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Old 03-08-2015, 06:55 AM   #5
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Trailer: Trillium
Posts: 835
All dc wiring in A camper is normally done with stranded wire. I would run all grounds to a common bus, and run a ground to the frame. # 14 wire is adequate for up to 15 amps of continuous draw. Each main run should be fused individually, but that doesn't mean you can't. Have. Several things on one circuit like at home, eg. 4-5 lights on one, water pump. On one, furnace. On one, fan on one.
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Old 03-08-2015, 10:09 AM   #6
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Name: Martin
Trailer: Boler
Posts: 180
When rewiring my Boler I used a Blue Sea bus bar and wired all the negatives to it and ran a wire from the bus bar to the frame. Bus bar is visible on the right side of the pic.

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Old 03-08-2015, 11:48 PM   #7
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Name: Walter
Trailer: Boler
British Columbia
Posts: 67
Run your appliances back to the common bus.

Run a line from your common bus direct to the frame.

Run a line from your common bus direct to the battery negative

Run a line from your battery negative to the frame.

This allows everything to travel the path of least resistance, while having a backup ground. Which is where most electrical snags occur.

Also use dielectric grease on all grounds.

Sent remotely
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Old 01-24-2018, 04:58 PM   #8
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Name: Adam
Trailer: Boler 1300
Posts: 5
what was your rational for putting the 40405 where you did? Im thinking of water tank in the rear right and electrical in the rear left (drivers). Do you have a water tank?

any lessons learned? thanks in advance :-)
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Old 01-24-2018, 05:40 PM   #9
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Name: bob
Trailer: Was A-Liner now 13f Scamp
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that is what I did I did away with the converter don't know if it worked or not. didn't care!


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