Earth neutral bond for inverter before I get grid hook up on new build.

[jimseng]

Quote

Yes we used their earth bonding. I added the earth rod when we installed the batteries and backup gateway.

I'm sorry to keep banging on about this but it is a complex subject without a definitive answer and easy to get wrong (and I bet many professionals get it wrong despite their qualifications).
@kelvin. When you added your earth rod, did you leave the SSEN earthing permanently in place? It seems to me that inverters in islanding mode probably leave the existing earth in place, which potentially is fine until there is a local cabling fault. However an additional earth rod would surely introduce a ground loop if the DNO earth isn't disconnected in islanding mode.
Maybe I am over thinking it but it seems this isn't a settled subject yet, and it should be simple to get right with the correct information.

Edited 4 hours ago by jimseng

[JohnMo]

We had to add an earth rod in addition to the the SSEN one, for running in island mode.

 

But if you make some basic assumptions

1. Mains is off and cable is broken or in your case not there.

2. You no longer have a safe proven earth path.

 

So a fault in house has no earth route in island mode. So you need to add an earth spike for that condition.

 

No earth spike no ground route except via you. Doesn't sound that safe to me.

 

So install earth spike for island mode and be safe, would be my answer. 

[jimseng]

@JohnMoI get that. I think I am being really pedantic, and I am considering the long term. Again, probably over thinking it but there are a couple of scenarios. And I am talking about where I am on grid and there is a power cut:

1. Power cut downstream of local earth point. DNO earth still remains so local ground spike creates and earth loop. -Bad

2. Power cut due to cable fault. No DNO earth. Local ground spike is necessary, no earth loop. -Good

It seems a simple thing to fit a double pole relay to create the local E/N bond and at the same time swap from the DNO earth to local earth rod. But I haven't seen a single mention of this being done anywhere, which, in my experience, doesn't mean it shouldn't be done, just that it is a detail that is ignored/ nobody cares/ hasn't been discussed.

[Alan Ambrose]

>>> But I haven't seen a single mention of this being done anywhere

 

It's a more unusual requirement and a lot of real sparks won't have thought about it and the regs probably don't cover it well.

 

But, see e.g. 

 

https://foxesscommunity.com/viewtopic.php?t=139

 

Earth Neutral Bond :

 

https://www.facebook.com/groups/571819024654208/posts/1072959771206795/

 

 

[Kelvin]

3 hours ago, jimseng said:

I'm sorry to keep banging on about this but it is a complex subject without a definitive answer and easy to get wrong (and I bet many professionals get it wrong despite their qualifications).
@kelvin. When you added your earth rod, did you leave the SSEN earthing permanently in place? It seems to me that inverters in islanding mode probably leave the existing earth in place, which potentially is fine until there is a local cabling fault. However an additional earth rod would surely introduce a ground loop if the DNO earth isn't disconnected in islanding mode.
Maybe I am over thinking it but it seems this isn't a settled subject yet, and it should be simple to get right with the correct information.

Yes it’s permanently in place in that it’s part of SSEN’s cabling system. The earth rod is there for when the house goes off grid and you lose the DNO earth in case you have a fault in the house. Interestingly there was an urgent notice from Sigenenery to their installers about the correct earthing requirements for the system. Some installers weren’t connecting an earth rod at all and some were but not cabling it correctly in the gateway. 
 

There maybe is a multiple fault scenario where neither of these are sufficient but what would need to happen for that?