Clause 4.3 of this standard states that rising mains require earthing yet electricians tell me that BS 7671 refutes that. Any comments?
As metallic services they should be main equipotentially bonded at the point of entry to the building back to the main earthing terminal (along with water main, gas main, etc). BS7671 applies.
My reading (of a freely available draft of the standard) is that the fire mains 'should be earthed in accordance with BS7671' which is not the same as saying 'should be earthed even if BS7671 says it shouldn't be'. So if BS7671 requires earthing of the fire main because it's considered an extraneous-conductive-part or because of some other criterion then it should be earthed. If, however, there is no requirement in BS7671 to earth the fire main, then BS9990 does not require willy-nilly addition of green/yellow wire.
In some circumstances BS7671 would explicitly prohibit earthing, such as earth-free locations (not sure how that would be workable with metallic fire mains)
