External garage electricity wrongly connected to neighbours supply

[SUNRAY]

Maybe I'm being dim, but could you perhaps explain that statement?

Other than in TN-C-S installations, there is not uncommonly a significant N-E potential difference (due to VD in the supply neutral) - and, indeed, even with TN-C-S there is not uncommonly a significant PD between the CNE/PEN (hence N & E within the installation) and 'true earth' (for the same reason). However, in no case does that result in any 'potential for tripping' of an RCD.

Of course it does.

 

[JohnW2]

Of course it does.

You may regard it as a matter of "of course" but, as I wrote, even if it's because of my being dim, I'd be grateful if you could explain why you believe (if I understand you correctly) that a significant N-E potential difference may result in an increased possibility of RCD tripping. Thanks.

 

[Harry Bloomfield]

You may regard it as a matter of "of course" but, as I wrote, even if it's because of my being dim, I'd be grateful if you could explain why you believe (if I understand you correctly) that a significant N-E potential difference may result in an increased possibility of RCD tripping. Thanks.

My guess as to what is meant.... With a potential between N & E, even when the MCB is off, shorting N to E, can cause the RCD to trip.