where installations are supplied from a pme supply it is often impracticle to extend the earth equipotential zone to remote buildings because of the interviening ground which exhibits true earth potential. this potential will be negative with respect to th pme earthg( at least when some load is being supplied and for this reason extending the zone would be undisirable.
(EXTRACT FROM PRACTICLE GUIDE TO 7671)
i was taught as long as you meet the disconnection times required then the earthing was deemed safe and acceptable?
also what does it mean by interviening ground which exhibits true earth potential. this potential will be negative with respect to th pme earthg( at least when some load is being supplied).
[This message has been edited by james S (edited 10-08-2003).]
