Neutral Ground Bonding

[Lee Bradley]

My question has to do with power sharing inverters. If I have the bus plugged into a 15 amp shore line and the inverter starts supporting the bus from the batteries, there is now two power sources. Where should the neutral/ground bond occur?

[Bill B /bus]

I can discuss a Trace SW4024 inverter.

The AC shore power input is to the inverter. When you limit the max input current the power sharing for the overload  is done by the inverter output. Ergo you do not have two power sources, just one.

I know clear as mud. Just do the bonding as per your manual for the inverter.

Bill

[bobofthenorth]

There's only one "right" way to do that IMHO and that's at the pedestal or panel but I'd be curious to know if that's what actually happens.  There's no way for the inverter to lift the shore bond so anything other than a single bond at the shore panel results in a double bond.  But I'm curious to know if that's what really happens.

[Emcemv]

Just an opinion but I think all neutrals in the bus should be common and connect back to the shore neutral.

[TomC]

The only time your ground/neutral should be not connected to the power pole is when you're not connected to the power pole. Grounding through earth is much more effective then through the chassis. Good Luck, TomC

[belfert]

What exactly is the issue if neutral and ground are bonded at more than one location?  I know it is a no-no, but why is it not to be done?

[Melbo]

There are two conductors that go to ground the "grounding conductor" and the "grounded conductor" then there is the ungrounded conductor which of course is the line voltage. The "grounded conductor" is the other half of a circuit and designed to carry current. The "grounding conductor" is the "safety valve" of the system and should only carry current in the event of a error or fault in the system. When tested if the "grounding conductor" has more than one "escape route" and that "escape route" is not capable of handling the load from the error you could become energized unintentionally. By having the only "escape route" at the "main power supply" the utility company or electric supply source will get the feedback and "should" be able to handle the error or fault that has occurred. So the simple answer is the ground should be as substantial as the electric supply and intermediate grounds that are not capable of handling the load will give you a false sense of safety.

HTH

Melbo

[Emcemv]

Neutral is a load current carrying conductor. Ground is a protective conductor, not current carrying except in fault conditions.  When you tie them together, you can get load current in the ground and that is a bad thing. They should only be tied together at the power source, at one point.

[bobofthenorth]

Sean is pretty busy putting his boat back together these days so I don't suppose he has time to keep us peons in busses safe but he has answered this question innumerable times.  Here's the first thread that came up on Google for me, look at the 4th post in the thread for one of Sean's usual detailed explanations of the risk.

http://www.busconversions.com/bbs/index.php?topic=18850.0