Main Bonding to lightning conductors

Deleted member 9648 · Oct 3, 2009

Hi all,
New to this forum so I'll introduce myself as an electrician working for an NIC approved contractor in Sussex.
Last week I did a PIR on a church and the only defect was a lack of main bonding to the lightning conductor. Bs 7671 lists this as a requirement but I cannot see why it is necessary, given that said lightning conductor is on the outside of the building and so outside of the equipotential zone. Also it seems to me that a bond on to the lightning conductor will simply 'import' a lightning strike into the electrical installation.
The NIC technical guide states that while a bond is required , the complexities of other british standards involved means that it should only be undertaken after consulting a L/C specialist,and should be listed as a code 3 on the PIR. If anyone can enlighten me on why bonding L/C's is a good idea I would be grateful
Cheer's ...Alan

pushrod · Oct 5, 2009

I remember asking a lecturer the very same question last year - did get an answer but for the life of me i can't remember what he said

i must pay more attention

Deleted member 9648 · Oct 6, 2009

Ta for that little nugget pushrod!

pushrod · Oct 8, 2009

Asked again and was told that the Earthing arrangement of the supply would almost certainly be better than the Earth for the lightning conductor (sounded possible). Also said that by linking it to the equipotential zone that there would be less chance of serious shock from extraneous conductors (wasn't quite so convinced by that). However, looked it up and the requirements for a LC earth is anything less than 10 ohms, so potentially much higher than the supplies earth. Also that there is substantial risk associated with "flash-over" from lightning conductors to extraneous conductors - so respect to him he knew his stuff.
More info HERE