DC Rocker Switch Panel Issue from Power Distribution Center

[gprescott]

Hey everyone - new to this thread so thanks for having me. I have an issue with my DC power in a small truck camper. I have 3 accessories plugged into 5 pin rocker switches on a single panel. I have daisy chained the neutrals together and the positive is fed to the power distribution box (WF8700 series). Red is tied into the grey output wire (fuse #2 15 amp) to run the multiple accessories. Small vent fan, water pump and LED recessed lights all on different switches, but again same feed wire. The 12V battery is connected into the red and black DC connectors. There is a ground (10 gauge) green wire that appears capped inside - I am a novice so unsure if that needs to get routed to the grounding bar on the breaker side of the box? Also, should my neutral/negative go to the neutral/negative bar or ground bar? I know I am making some people cringe here but forgive me as I am just an office job guy trying to figure this out. When I plug my water pump or fan etc. directly into the switch or battery directly, everything works fine. Any ideas on the concern? Also, the camper came with a battery multimeter to sense load and remaining charge (still in box). It has your standard two black, two red, and blue and yellow wires and the metal bar. Can someone walk me through the bus bar and how to wire that? Thank you in advance. Set to take this camper on a 3K mile trip in 5 days and need to trace this issue soon.

 

[Lucien Nunes]

I am familiar with these power centres up to a point, but your description is a little unclear. Can you post some pics of your setup? Also, you do not actually say what the main problem is?

Re: ground, neutral and negative. On AC circuits there is no negative or positive. The return wire of the AC circuits is neutral and is insulated from ground, although unlike the hot it is similar to ground in voltage. The ground wire is there for safety and does not normally carry current.

On DC circuits one wire is positive and the other negative, and on all modern vehicles the negative is the return wire. However, confusingly, instead of neutral, it is often called ground, because in vehicles the return path uses the chassis and bodywork, and in electrics and electronics it is often assumed that any big metal thing will be at ground potential.

So at the power centre, there will be a DC negative bar which carries all the DC return current, and which is likely to be connected to the chassis. The AC ground bar or lug might be connected to the chassis too, but this doesn't normally carry current. The AC neutral bar or lug is a different deal; it should not be connected to anything else, as it is part of the AC power circuit that should be completely insulated from the truck.

 

[gprescott]

I am familiar with these power centres up to a point, but your description is a little unclear. Can you post some pics of your setup? Also, you do not actually say what the main problem is?

Re: ground, neutral and negative. On AC circuits there is no negative or positive. The return wire of the AC circuits is neutral and is insulated from ground, although unlike the hot it is similar to ground in voltage. The ground wire is there for safety and does not normally carry current.

On DC circuits one wire is positive and the other negative, and on all modern vehicles the negative is the return wire. However, confusingly, instead of neutral, it is often called ground, because in vehicles the return path uses the chassis and bodywork, and in electrics and electronics it is often assumed that any big metal thing will be at ground potential.

So at the power centre, there will be a DC negative bar which carries all the DC return current, and which is likely to be connected to the chassis. The AC ground bar or lug might be connected to the chassis too, but this doesn't normally carry current. The AC neutral bar or lug is a different deal; it should not be connected to anything else, as it is part of the AC power circuit that should be completely insulated from the truck.

Hi, thanks so much. Photos are above of the setup. My problem is, when I flip one rocker switch, the others go off (LED indicator goes off). No DC powered accessories turn on. If I don't have a metal chassis (its wood) how do you recommend I ground?

 

[Lucien Nunes]

Sorry, still not quite sure what the problem is. When you say 'flip one rocker switch' do you mean on or off? Please say explicitly what works in which switch positions, and what doesn't work in which switch positions. Is there a battery connected at the moment or is the only source of DC power the converter built into the power centre?

 

[gprescott]

Sorry, still not quite sure what the problem is. When you say 'flip one rocker switch' do you mean on or off? Please say explicitly what works in which switch positions, and what doesn't work in which switch positions. Is there a battery connected at the moment or is the only source of DC power the converter built into the power centre?

When I flip a rocker switch to the "on" position, it appears to close the circuit on all others, whereas their LED indicator lights go off. I have somehow broken the chain. Each one has that same issue. Besides the LED indcator lights, no power is evident anywhere. Meaning I cannot power on the accessories from the switch. There is a battery connected to the power center in addition to AC.

 

[Lucien Nunes]

It sounds like you have a high-resistance connection between the power centre and the switch panel, in either the positive or negative wire. The resistance is low enough to light the LEDs on the panel, but too high to power any of the accessories. When you switch any of them on, the voltage at the feed to the panel collapses and the LEDs go off.

You can check this with a multimeter. Set it on 20V and connect across positive and negative at the panel. You should see voltage while the LEDs are lit, possibly not the full 12V due to the resistance, but then when you switch something on, that voltage will reduce dramatically. Having proven that this is what is happening, you can try the same at the power centre main negative and fuse output, and prove whether it does or does not happen there too. Then you will know whether the problem is within it or in the wiring.

If you have a small 12v filament lamp (not LED) you can use that instead, to check whether it lights at the common neg and pos at the panel and the same at the power centre.