On 08/06/17 19:04, ARW wrote:

I would say it discounts the TT as TT has no distributors earthing
facility.

Agree.

It does also help with scenarios where one might run temporary from a
genny or UPS and the supplier's earth is in doubt during a power failure.

But does it say "and you must have 100% RCD protection"? Without that
it's pointless.

I know the other parts require 100% RCD coverage (if I read it right?)
for new installations, but if this part of earthing and bonding is made
retrospective on any major works being done (in the same way that
verifying main EB and supplementary EB where applicable is), then it
would be a bit odd.