On 28/04/2017 08:21, Tim Watts wrote:
On 28/04/17 01:39, John Rumm wrote:

Although the loop test does not find the metal that does enter the EQ
zone, and could be made live by a fault, but is not bonded at entry (say
a partial metal pipe install where the incoming main and initial
pipework is plastic, and hence not included in the main bonding)

Hi John,

I need to dig out the big red book (I know..) and find the exact wording.

But from memory, doesn't the 17th say:
plumbing that is extraneous must have continuity back to the main bond,
or something along those lines.

In other words, if you have pipes entering the bathroom which do not
have continuity to the MET, then you cannot meet the conditions for not
having SB.

The one thing I am not sure of is what "continuity" means here, and I
really do need to check.

It could mean "sufficient to trip an RCD" or it could be "sufficient to
disconnect a fuse/breaker in 0.4s".



Sufficient to trip a 30mA RCD.

Which of course may might when then the electrician did the work but may
fail when some pipework is altered (and that pipework need not be in the
bathroom).

Local supplementary bonding removes that risk.


--
Adam