Where above apply to quarries where PME is not allowed, I would say PMB, where is the tick box.
I think part of the confusion is that not only are there two version of TN-C-S (PME and PNB) there are also two versions of PNB (TN-C-S and TN-S) - i.e. PNB could be either TN-C-S or TN-S depending on relative positions of the Earth connection and the N-PE link.
Some DNOs seem to suggest that PNB should always be treated as if it's PME - not because it necessarily is - but as a safety margin in case the DNO re-arrange things and make it TN-C-S at a later date.
Where above apply to quarries where PME is not allowed, I would say PMB, where is the tick box.
I think part of the confusion is that not only are there two version of TN-C-S (PME and PNB) there are also two versions of PNB (TN-C-S and TN-S) - i.e. PNB could be either TN-C-S or TN-S depending on relative positions of the Earth connection and the N-PE link.
Some DNOs seem to suggest that PNB should always be treated as if it's PME - not because it necessarily is - but as a safety margin in case the DNO re-arrange things and make it TN-C-S at a later date.
