ostrichwrangler avatar image
ostrichwrangler asked

Earth bonding inverter output in a camper installation

I have installed a Phoenix 12|500 inverter into a panel van camper conversion, with the DC input side connected to the 12v leisure battery & earth connection bonded to the metal chassis of the vehicle.

On the output side I am running a fused (3a) 3-pin plug into a two-gang RCD-protected plug socket, providing short circuit protection in the instance of a live fault raising the potential of the chassis to 230v and some poor soul stood on wet earth outside knocking on my door.

However I am left wondering what overcurrent protection there is on the output side. From what I understand in the product manual there is no continuity of earth (chassis) bond from the input to the output side. Ought I make an additional connection to the vehicle chassis on the output side to facilitate overcurrent operation of the 3a fuse in the case of an appliance fault?

Happy to answer queries and share pictures if beneficial. Thanks for helping with my head-scratcher..

Phoenix InverterGrounding
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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

I'm not sure I'm understanding your connection method but there should never be a fuse in the safety ground circuit. That path needs to be able to carry all fault current from the short back to the service entrance.

The inverter was a COMMON safety ground connection (labeled PE) for input AC, output AC and chassis. The incoming AC safety ground as well as the outgoing safety ground to the RV outlets and the RV chassis should all be connected to this common safety ground path. It is the incoming NEUTRAL connection that opens when the unit is functioning as an inverter (not using the AC input). The output neutral then connects to the safety ground. This "ground relay" then provides a fault path for inverter supplied power in the same way that the neutral to safety ground bonding in the service entrance panel does for a building.

I believe Victron recommends an RCD on the inverter output since the input RCD won't detect a ground fault when the inverter is inverting (not using the AC input). At the very least, an overcurrent protection device should be used to avoid inverter overloads. Local codes would be a good source to check for what's needed.

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