solar-samuel avatar image
solar-samuel asked

Shore power ground fault on a bonded neutral generator

I have an 50A RV with a custom solar setup using a 12v Multiplus II 2x120v inverter. In normal operation I run shore power through an EMS and the into the Multiplus, then from the Multiplus into the original OEM panel. Everything has been working flawlessly with the system since I installed it 1.5 years ago.

Recently I purchased a new Ford truck with a 2kw generator function "Pro Power Onboard". This was a significant feature, as I thought it would allow me to provide supplementary power to my system when the solar panels alone can't quite make it.

However, this generator system is set up in the truck with a bonded ground/neutral, and when plugged in as a shore power source for the RV immediately triggers a ground fault and does not function. I'm assuming this is because the trailer is also bonded at it's panel and this creates a flow of power on the ground which should not be there.

A common fix suggested is to remove the ground wire connecting the truck, and just run a hot and neutral line into the trailer. However, I'm a bit uncomfortable with this solution, as it does not seem safe. But I don't really have the electrical knowledge to fully assess this one way or another.

Does anyone have any ideas as to how I can successful use this bonded neutral generator as a shore power source for my system?

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rh5555 avatar image rh5555 commented ·
Where in this system is your ground fault interrupt? In the truck?
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2 Answers
derrick thomas avatar image
derrick thomas answered ·

The trailers panel should not have a neutral to pe ground, if it does it is wrong. When the trailer is connected to shore power (the grid) the bonding is done at the main panel feeding the shore connection outlet. If there is an onboard generator, it most likely will also be bonded at the generator. When running on inverter with no shore connection, the inverter takes care of the bonding. If you have bonded the panel on the trailer, remove the bond, it is dangerous.

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xerxiz avatar image
xerxiz answered ·

The Multiplus has a ground bonding relais, that can be configured to bond N and PE if the inverter is the power source. If the shore power or generator is ground bonded already you have to make sure the plugs are coded correctly (like CEE plugs), so N and L1 can not be switched by turning the plug by 180 degrees accidentally.

I guess that was the case, when you tried it.

In general the bonding shall be done as close to the power source as possible and you should add an RCD breaker right after it.

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