Should I tie my negative bus bar to chassis (A) given the case ground I have on my Multi (B) or is this redundant and unnecessary? The DC Loads and Tongue Jack (C) are the primary (and possibly only) beneficiaries.
EDIT: I forgot to mention that my question is identical to asking if I should tie the case ground of the MP2 to the negative bus bar (and ground them both to chassis).
One advantage to connecting negative to the chassis ground in a vehicle (or hull on a steel boat) is if you get a positive wire wearing through the insulation to the metalwork is a path is then created for the short circuit current to flow and blow the fuse. It also provides a common 0V reference for both vehicle and house systems.
In a little more research I’ve learned that it’s not ideal to even use the chassis as a current path. Manufacturers do it to save cost, weight, and time. I have rather short runs anyway, so I’m now considering running a negative wire to my DC panel.
I think you are correct once you get high currents for your domestic equipment, wire the negatives direct and have one connection to chassis to give you the common 0V with the engine battery.
It’s a trailer, so no engine, but the point stands. Thanks, @pwfarnell.
In the trailers I’ve built the MP case is grounded to the neg bus bar, and the neg bus bar is grounded to the chassis. There are a number of things from the factory that are chassis grounded so I want to make sure they all still work, in addition to the reasons @pwfarnell listed.
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Thanks, Jeremy!
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After your feedback and a bit more thinking, here’s an updated diagram. I have a single chassis ground (A), in my Multi I’m bonding PE and negative (B) which I assess is the equivalent of running each independently to chassis ground, I am running my AC distribution panel’s ground bus to the negative bus bar to ground that as well (C), and I’m considering letting my DC Loads use the chassis for current for now instead of pulling another wire. Thoughts are welcome. I wonder specifically about tying the PE and negative in the Multi. In this diagram I found online, the entire system floats except for the Multi’s chassis ground. Mine is different in that I have negative loads going to ground, so ground and negative are the same for me.
