12V wiring Aluminum Cargo Trailer conversion

DrewE wrote:

SlideInDad wrote:

If the IOTA45 converter is simply properly bonded to my house 120V what purpose would the chassis ground serve?

The converter chassis needs to be bonded to the RV chassis (as is detailed in its installation manual), and the 120V ground needs to be bonded to the RV chassis.

The 120V ground to chassis connection is for safety in case there should be an electrical fault in the 120V wiring, causing the hot to short to the chassis. If the chassis were not grounded, it would be hot and pose a shock hazard to anyone entering or exiting the RV (a hot skin). Having it bonded to ground prevents that, and assuming the short is low enough impedance causes the breaker to trip due to overcurrent.

The 12V bond is a bit more subtle. As I understand it, it is practically speaking impossible to totally isolate the chassis from 12V negative ground with typical appliances and lights, and so it's likely that the chassis will be connected to the 12V negative side somehow or another. If there's not a good bond between the battery and the chassis, and the converter output and the chassis, then there's the opportunity for all of the converter current to find its way through e.g. the 120V ground wire or the ground wires for various 12V appliances back to the battery in the case where the main wire from the converter's negative output to the battery is broken or disconnected. This amount of current can easily be a dangerous overload for those wires; hence, as a safety precaution, they must be tied to the chassis with a low impedance wire that will carry the fault current safely.

Assuming you have electric trailer breaks with a breakaway switch, the trailer chassis will have to be grounded for that system to work properly. (I guess that's also assuming you're using the house battery for the emergency braking power, which is standard practice. Having to maintain two separate batteries when one will do just fine on its own seems...well, silly.)