Forum Discussion

Just_There's avatar
Just_There
Explorer
Feb 03, 2019

Ground-Neutral bond

Please help me to understand grounding and neutral bonding. This assumes the transfer switch between shore power and generator switches both hot & neutral. This is how I understand it with a big question at the end.

On-board Generator:
Ground, neutral, chassis all bonded together.

Shore power:
Ground wire, neutral bonded & grounded to earth at or upstream of pedestal.

Battery bank:
Negative through shunt, then bonded to chassis.

PV charge controller:
No ground.

Inverter-charger w/ auto transfer switch:
Case bonded to chassis.
¿Neutral & Ground Bonded? Yes/No
  • wnjj's avatar
    wnjj
    Explorer II
    Just There wrote:
    Thank you! I now see where the Aims 2000 I’m looking at does indeed have a relay to break the bond with external AC. This goes along with what I’ve always heard: only bonded in one place at source of power. Gets kinda confusing with multiple sources. A follow up question, if I may:
    Would the proper place for hard wired EMS surge protection be between the inverter and the Genset/shore power transfer switch?

    The EMS should be between whatever power source that could have trouble and whatever you want to protect. I don’t think a generator or inverter is likely to have issues so if it were me, I would probably put one between the shore power cord and the transfer switch. That way even your transfer switch itself is protected. It may come down to wiring and mounting convenience.
  • Thank you! I now see where the Aims 2000 I’m looking at does indeed have a relay to break the bond with external AC. This goes along with what I’ve always heard: only bonded in one place at source of power. Gets kinda confusing with multiple sources. A follow up question, if I may:
    Would the proper place for hard wired EMS surge protection be between the inverter and the Genset/shore power transfer switch?
  • You've got it right for most all situations I can think of. Your inverter should bond then neutral and ground when inverting and disconnect them when passing thur AC power from another source. Inverters designed for mobile use typicall have this feature. Inverters designed for use in a structure usually don't.
  • Inverter will depend on the model. Although I believe most that are made to wire into an RV/marine electric system will bond during inverting function.