Angus poses this question, which concerns the earthing arrangements of two buildings. He asks why they cannot be connected together. It has been answered by the NICEIC (Theme – Regulations & Legislation):
Question: We have a scenario similar to the arrangements shown on pages 65 and 66 of Guidance Note 8 IET 'Earthing and Bonding' (copies attached in pdf).
Can you please advise as to why the earthing arrangements of buildings B1 and B2 can't be connected together?
To me, it appears that the earth spike arrangement on building B2 is identical to the bonding of the pipe shown at building B3, where the earthing arrangements of these two buildings are connected together.
Answer: The example shows B1 as a supplier's earthing arrangement and building B2 as a TT arrangement. They are separate earth arrangements, so should not be joined.
If they were joined, then this would be the same arrangement as B1 to B3. However, the sizing of the conductors would not be sufficient for fault conditions.
This also depends on the location of the buildings and whether they fall under the requirements of special locations in the Wiring Regulations, which can preclude the use of a protective multiple earth (PME) to certain buildings.
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