I have an inverter without a grounding point, how do I ground it?

[Rumbaar]

I've purchased an inverter that doesn't appear to have any external manufacturer ground point, even though it has an AU plug and includes (from appearance) live, neutral and earth connections for an AC output.

I've got a common ground in my fuse box, which I have my PV panels and charge controller connected too. But not sure how I go about grounding/earth my AC connections via this inverter.

Anyone experienced this and know the best solution?

 

[NVS]

I would think the chassis is tied to the ground. Use a meter and check for continuity between them. If so ground the chassis.

 

[MichaelK]

Make the main electrical box the focal point of all your grounding elements. All above-ground circuits, and above-ground electronics get bonded at your electrical box's grounding buss. You also run a ground wire from your inverter's internal grounding terminal to that same grounding buss.

Then you run a heavy 6 gauge copper wire (4 gauge for 200A service) from that buss outside to the exterior ground rod. Your ground rod should be connected at no other spot inside the building. You may have multiple earthing elements like metal rebar, or underground water pipes, but they should all be connected in series to that same 6 gauge wire connected to the ground rod.

 

[Rumbaar]

I would think the chassis is tied to the ground. Use a meter and check for continuity between them. If so ground the chassis.

Yeah, supposedly the ground is the output for the AC outputs and I ground via connecting to the ground/earth of that connection.

Make the main electrical box the focal point of all your grounding elements. All above-ground circuits, and above-ground electronics get bonded at your electrical box's grounding buss. You also run a ground wire from your inverter's internal grounding terminal to that same grounding buss.

Then you run a heavy 6 gauge copper wire (4 gauge for 200A service) from that buss outside to the exterior ground rod. Your ground rod should be connected at no other spot inside the building. You may have multiple earthing elements like metal rebar, or underground water pipes, but they should all be connected in series to that same 6 gauge wire connected to the ground rod.

Yeah, this is what I've done for my shed, off-grid, setup. I have a earthing rod in the ground and an earthing wire from that to the busbar in my shed fuse box. Then I have all other devices in the setup back to that common busbar.

But after doing all that, there doesn't appear to be a working ground/earth as I'm getting that fault in my plug tester. My earthing rod isn't that far into the ground, would that affect that? But I need to learn/investigate now why I'm not getting a grounded system.

 

[MichaelK]

But after doing all that, there doesn't appear to be a working ground/earth as I'm getting that fault in my plug tester. My earthing rod isn't that far into the ground, would that affect that? But I need to learn/investigate now why I'm not getting a grounded system.

What that sounds like to me is a ground fault. That means there's a second ground to neutral connection somewhere downstream of the main electrical box. One suggestion I could suggest is try disconnecting your neutral wires from the bussbar one by one and see if the fault goes away. If it does, you know that the neutral in question has a connection to ground somewhere.

How deep is the ground rod? Standard is 8 feet. Is it because you have very rocky ground and can't get the rod deep enough? My understanding is that two-4 foot rods, spaced at least 6 feet apart, and wired in series to the ground buss, is considered almost as good as a single 8' rod. Alternatively, for really rocky ground, a bare copper wire, laid in a trench, can make an acceptable ground. You'll need to look up how long and how deep that needs to be?

 

[Rumbaar]

What that sounds like to me is a ground fault. That means there's a second ground to neutral connection somewhere downstream of the main electrical box. One suggestion I could suggest is try disconnecting your neutral wires from the bussbar one by one and see if the fault goes away. If it does, you know that the neutral in question has a connection to ground somewhere.

It's a totally new PV/DC fuse box created just for this shed, and has only 3 connections on the ground busbar. The PV array, I've run a earth wire from each panel (3 panels) in series back to the busbar, I have the charge controller connected to the same busbar, I have (I think) the ground from the inverter back to that bus bar and there is a ground/earth wire from that to a grounding rod next to the shed in the ground.

How deep is the ground rod? Standard is 8 feet. Is it because you have very rocky ground and can't get the rod deep enough? My understanding is that two-4 foot rods, spaced at least 6 feet apart, and wired in series to the ground buss, is considered almost as good as a single 8' rod. Alternatively, for really rocky ground, a bare copper wire, laid in a trench, can make an acceptable ground. You'll need to look up how long and how deep that needs to be?

Yeah, I have a 'standard' Earth rod of around 1440mm (4.7ft) and yes it's only in not even a 3rd of that due to hitting rock and I need to move it to until I can get it all the way into the ground. I guess I need to start with getting that rod into the full length into the soil, and also look up minimums.