Hook the trusses all up to each other with a copper wire and suitable clamps, and extend the copper wire to a grounding rod, with a similar clamp. Your local electrical code will probably tell you the correct sizes of stuff, or give means of calculating.
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In vino veritas; in cervisia carmen; in aqua E. coli.
It is unusual to earth trusses in the UK, though BS7671 does allow additional equipotential bonding to be carried out without additional testing once the Building Regulations Part P certificate has been raised.
BS7671 does require metal water pipes to be bonded to earth, so that in the event of a live conductor making contact with one, the person using the basin tap doesn't get electrocuted; the circuit protective device operates before it can happen.
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Earthing
Re: earthing
