Pv array earthing why?

SolarCity · Sep 23, 2011

Yes, on a TN-C-S system

Werneroeder · Sep 26, 2011

And how about a TT system using ClassII equipment and mounting on a wooden structure, where the array is 500 meters from the CU? Would I use a localised groundspike, but do not connect it to the earth coming from the CU?

malcolmsanford · Sep 26, 2011

Why would you want to earth/bond wood?

SolarCity · Sep 26, 2011

I'd be careful installing a TL inverter on a TT system anyway. TL inverters don't like high impedances

moggy1968 · Oct 2, 2011

personally i always bond the array and always bond to the MET if it is attached to the house.
the registering bodies will allow you to transport the earth to a detached garage as long as it is 'not too far away' so if thats allowed I see no reason why the array cant be treated the same, especially as it's actually attached to the building.
If there was a fault on the array due to a damaged cable it could short on the array presenting a hazard to anyone going up to work on it. given that this also involves working at height this could potentially be very hazardous, thats why I bond it.
If the array can be reached, i.e. through a velux then earthing the array is an absolute.

SolarCity · Oct 2, 2011

moggy1968 said:
personally i always bond the array and always bond to the MET if it is attached to the house.
the registering bodies will allow you to transport the earth to a detached garage as long as it is 'not too far away' so if thats allowed I see no reason why the array cant be treated the same, especially as it's actually attached to the building.
If there was a fault on the array due to a damaged cable it could short on the array presenting a hazard to anyone going up to work on it. given that this also involves working at height this could potentially be very hazardous, thats why I bond it.
If the array can be reached, i.e. through a velux then earthing the array is an absolute.

You're in the minority with that conclusion but I have to say that I fully agree with you.

malcolmsanford · Oct 2, 2011

moggy1968 said:
personally i always bond the array and always bond to the MET if it is attached to the house.
the registering bodies will allow you to transport the earth to a detached garage as long as it is 'not too far away' so if thats allowed I see no reason why the array cant be treated the same, especially as it's actually attached to the building.
If there was a fault on the array due to a damaged cable it could short on the array presenting a hazard to anyone going up to work on it. given that this also involves working at height this could potentially be very hazardous, thats why I bond it.
If the array can be reached, i.e. through a velux then earthing the array is an absolute.

'not too far away' So what is the definition of that 5 metres, 10 metres anything over, not sure why you consider extending the equipotential zone is distant related, unless you have extraneous conductive parts that needed bonding.

If the array can be reached, i.e. through a velux then earthing the array is an absolute is that for any installation regardless of the inverter type??

moggy1968 · Oct 2, 2011

'not too far away' is exactly what ELECSA said to me, I pushed them for a definition but they wouldn't be commited. That was on the phone. This was my assessment installation and the assessor didn't querry it. the garage was about 5 metres from the house, so a fair distance. Yes, for any inverter. an Inverter with a transformer gives electrical seperation of DC and AC circuits, it has no bearing on earthing the array. likewise I saw somewhere on here a suggestion that some inverters effectively have their own 'RCD' in them (although different terminology is used) and this negates the need for an earth. this if course won't affect the array bonding because the inverter is 'downstream' of the DC cables and array.

malcolmsanford · Oct 2, 2011

Well shame on ELECSA it seems they are being influenced by the NICEIC and having their take on the regulations, and by an assessor just blanketing giving advice such as "not far away: IMO opinion is bordering on negligence, not far away give me a break!!!

It would only be TL transformers you would earth/bond the array frame, I just wonder wondered as the statement read that any frame that can be touched while in the equipotential zone should be so,

moggy1968 · Oct 2, 2011

As I understand it bonding the frame has nothing to do with the transformer. the transformer gives electrical seperation of the DC and AC. we are treating the frame as an extraneous conductive part and I would always be inclined to earth the frame, regardless of what transformer is used.

Sparkytlec · Oct 3, 2011

moggy1968 said:
As I understand it bonding the frame has nothing to do with the transformer. the transformer gives electrical seperation of the DC and AC. we are treating the frame as an extraneous conductive part and I would always be inclined to earth the frame, regardless of what transformer is used.

It has every thing to do with a transformer if the frame becomes live with a transfomer then it stops current flow from reaching earth of the AC system. If someone touched it then the current woud not compleat any circuit so no nead to earth. If you earth with a TT or TN-S system then you must earth to the MET as using a spike could have a differant potential to the MET and if you have PME then you must use a spike as the earth on PME is a combined nutral earth that would make it more dangrous if someone on a ladder were to touch the live array as the earth point on PME is back at the DNO transfomer.

SolarCity · Oct 3, 2011

Edit: Ignore me - I just woke up and I misread your post

Rw1001 · Oct 19, 2011

All mcs approved panels are class 2 double insulated. The dc cabling is also double insulated. For this reason I wouldn't earth the mounting system any more than I would earth metal guttering or tv aerial bracketry.