"the neon uses neglible load but the installation is incorrect as the shower has no means of local isolation and will require a d/p switch to satisfy a test cert".
Paul - would you care to explain why a means of local isolation is needed? I grant you it's good practice, but that's not the same as saying that not having one makes the installation incorrect, or that one is required to satisfy a test certificate.
Which regulation(s) back up your claim?
Concerned of London
August 2009