Load center wiring

[Geewizard]

Here's my question: If one were to disconnect the negative cable from the battery to the load center (fuses, breakers, etc) AT THE LOAD CENTER, shouldn't one have no power to all the 12v devices?

And if one still has 12v going to those devices with that negative cable disconnected, doesn't that mean there's a wiring error? Such as the negative part of the circuit being carried by ground wires?

Just curious.....

[trail-explorer]

Geewizard wrote:
I think it is because the negative terminal of the battery is connected to the frame ground as are the ground wires.

YEP. THis.

[mkirsch]

Original post is from September, 2021.

[JimK-NY]

Geewizard wrote:
I'm not on shore power nor am I connected to the truck.

If I disconnect at the battery end, everything is unpowered as it should be.

I'm trying to find out if this is normal. I think it is because the negative terminal of the battery is connected to the frame ground as are the ground wires.

If you disconnect the battery, and the truck pigtail is not connected and there is no 120 v power, and you are not connected to solar, then it is normal that there is no power to any 12 volt device. If there were I would seriously wonder where the power was coming from.

The negative terminal of your battery might be connected to the frame. That is the way cars and trucks are wired. That is not the way my RV is wired. The frame is not used at all. In fact there is no metal frame, just wood. The negative wire runs to the power station. My solar is wired separately. There is a wire from the solar controller directly to the negative terminal of the battery. I also wired my NovaKool compressor refrigerator with a negative wire that bypasses the main electrical system and goes directly to the refrigerator. It was the easiest way to bump up the wire gauge.

[Camper_Jeff___K]

If the negative is disconnected from the house TC batteries, no current will be flowing through the house system however, if you have hooked up the 7 pin plug, the negative wire is un switched and could complete a circuit if the key is on or switch is on completing the circuit via the truck battery. The house would be disconnected but truck power would be present. Try disconnecting the truck negative and that should cease all current flow.

[cewillis]

Geewizard wrote:
I think it is because the negative terminal of the battery is connected to the frame ground as are the ground wires.

This seems right to me - distributed ground, not single point. Probably common practice. The only (and better) way is to have ALL the ground connections wired to a single point.

[Geewizard]

Yes, I have traced the negative battery wire from both ends and it runs directly from the battery to the load center. And yes, I do know and understand that the frame is ground. I don't find any bare ground wires inside the load center attached to the negative battery wire. They are separate.

This isn't a real big deal but more of a question of why the bare ground wires, which are bonded to the frame, are carrying a load at all.

[enblethen]

A ground wire from the shore power cable into the 120 volt load center should be attached to the frame and to the ground wire to the receptacles.
When using batteries and disconnect the negative cable from the battery, there is no path to power 12 volt devices.

[BB_TX]

Fisherman wrote:
What BB TX said, the black, - cable from the battery is also attached to the frame and any items like lights, etc may be grounded to the frame.

It is also possible the ground wire from the load center actually attaches to the frame somewhere, not the battery. And the battery cable attaches only to the frame. The frame is ground.

Again the question is; have you traced the ground wire from both ends?

[Fisherman]

What BB TX said, the black, - cable from the battery is also attached to the frame and any items like lights, etc may be grounded to the frame.

[Bedlam]

May be getting feeds from truck pigtail, AC converter or solar controller even with battery disconnected. I found some items don't run through the panel and have a direct line to DC with an in-line fuse.

[pianotuna]

No it is not normal.

[SoonDockin]

I have been going through my Arctic Fox wiring. The only other source of power I was seeing was from my 20 watt solar panel on the roof. It still manages to supply 12v in the shade but not enough amps to power anything. I disconnected it while working on it.

[BB_TX]

I would expect the battery ground cable to be connected to the frame as well as the load center. In that case, disconnecting ground from the load center would not disconnect ground from the battery.
Did you trace the ground wire to see where or how many places it is connected?

[valhalla360]

Depends.
- Brakes are often direct wired to the battery thru the emergency breakaway switch, so it doesn't accidentally get disconnected while towing.
- Propane detectors, you don't want them accidentally disconnected.
- Solar often bypasses the 12v panel, so it can keep the battery charged when in storage.
- Inverters may have their own connection to the battery, so it can be placed close to the battery bank. Long runs of 12v at high amperage tend to have big voltage drop.

If you want to be sure everything is disconnected in storage, put in a disconnect at the battery that disconnects everything at the battery terminal.