We have two 11Kv/0.4 Transformers configured on a PWN from a single DNO POC on an industrial site. The neutral point of each TX are commonly bonded at the MV side. Each TX has its own earth mat consisting of multiple electrodes. Both mats are electrically connected via buried bare copper conductor between (100m apart).
Originally the site had one TX feeding one building. Due to a recent building addition there are now two supplies effectively feeding one larger building. Both buildings are steel framed and are joined at the structures. Couldn't upgrade original TX due to increased load required.
What demarcation if any, is needed for earthing within the steel framed buildings? Will the two buildings (into one) be considered separate earthing arrangements or due to the MV side of both being bonded single earthing arrangement - 542.1.3.3 appears to contradict?
Several other issues also spring to mind including adequacy of protective devices, circulating neutral currents and EMC.
Many thanks in advance for any thoughts