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Im going to give NAPIT tech support a call later today but thought id try to get some other expert opinions too.

Ive just carried out a EICR on a remote property in the Welsh borders. Its a new installation and new build ECO friendly house which has been built over 4 years with the electrical installation carried out by the owner under 'some' control by a local electrician. the electrician has not been able to test it however as he does not have third party registration. I spoke to local building control who basically said it was up to me whether to carry out a new installation cert or EICR. I went for EICR as more thorough.

My query is about the supply system i should enter on the cert. It is entirely off grid powered through PV arrangement with back up generator which kicks in when batteries drop below 45%. both feed in to the inverter equipment which contains the interlock switching to prevent both supplies being energised at the same time. It is a self contained system which has been certified by the installer with no earth connection to any public distributors supply. The owner has installed 2 x earth electrodes connected to a main earthing bar which has a solid link to Neutral at the point of source. From there all earthing is in seperate earths and CPCs

All readings are good with 137 ohms through the mass of earth between the electrodes and a Ze of 0.86 ohms at the consumer units. All circuits give v good results. so finally to the question. Do i enter TNS for this system on the Cert or could it be classed as IT?
Many thanks for reading....
 
If it has a solid link to the neutral bar I can't see how it can be TNS I would of thought it is a TNCS.

Would you be able to sketch it out or put up a couple of pictures ?
 
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If it has a solid link to the neutral bar I can't see how it can be TNS I would of thought it is a TNCS.

Since the source of supply is at the property, the neutral-earth link is doing the same job as the one that would otherwise be at the DNO's local transformer for a TN-S supply.
 
Yes, I have thought about that, and didn't really read it correctly.

On our supplies that come from our HV transformers (no other customers connected) we have them as PNB this is indeed a type of TNS.
 

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