domestic earthing

[whittledr]

Currently in a TT earthed property. The supplier refused to connect to incoming as its too close to the ground to physically fit.
TT has always given good readings to not cause any issue.
It has been mentioned to me by a qualified HV spark that I could simply tag my main earth terminal to the neutral of the intake to create a PEN. While I understand that would 'work' is it a good idea?
I know he knows what he is talking about but I am often doubtful of his advise in general!

 

[pc1966]

The use of 100mA delay incomer avoids that in all but the most flaky of installations.

If you are going to have an up-front RCD for traditional TT use then don't make it a normal 30mA instant one as it will be prone to tripping with the whole house on it.

Using a 100mA delay RCD there will avoid that as you are very unlikely to have as much as 50mA of normal leakage, and the delay aspect avoids spurious trips on switching events.

 

[Julie.]

OP wrote PEN earthing. Is that not a different earthing system to PME?

PEN means Protective-Earth Neutral and refers to the same conductor being used for the Neutral and Protective earth, strictly the cable/technique is CNE (combined neutral + earth) as opposed to SNE (separate neutral + earth) but it's widely used it's probably more common than the proper term. (Like calling transmission towers "pylons").

If you combine the neutral and earth then it's generically known as TN-C-S of which there are several types PEB - the CNE conductor is earthed at one point only, PNB - the CNE conductor is connected to neutral at one point only and PME - the CNE conductors are earthed at multiple points through the lv network.

Although most people think TN-C-S is the same as PME this is not the case, although synonymous in built-up areas; in more remote areas where there is just one customer to one transformer if an earth is provided, it is likely to be PEB - formal earthing at the transformer only.