Bathroom supplementary bonding - specific question

[Geo]

I have been following the bathroom electrics Wiki thread and have a supplementary question... House (1969) had no bonding. I recently added main bonding gas/water/electric. In 1997 a plumber fitted a power shower on a wall and above the enamelled bath and an electrician wired the inbuilt pump to a fused spur. The shower is fed with plastic water pipes - the rest of the house plumbing is metallic (mostly stainless steel). Reading the above thread, I think that he should have added bonding from the bath tap supply pipes to the shower - is this correct - or was it not required in 1997?

[John Rumm]

Including the pipes to the bath and basin taps?

'97 would have been the 16th edition where the rules are similar to now. From your description I would expect the bonding to include the pipes feeding the taps (bath and basin), the CPC of the lighting circuit, and the CPC of the circuit feeding the shower pump (plus that of any other circuits that enter the room). Plus any other extraneous metal that could bring a potential into the room, like radiator pipes. The shower unit itself probably has an earth connection and this is ok to double as a bonding conductor in this circumstance.

[Andy Wade]

Err, not quite because the rules changed during the life of the 16th ed. 1997 pre-dates the 2000 amendment to BS 7671:1992 - i.e. the amendment which introduced zoning and the need to bond the CPCs of all circuits feeding equipment in the zones, even Class 2 equipment.

Prior to said amendment (and going back to the 14th ed. (IIRC) the requirements were to bond between:

- simultaneously accessible exposed-conductive-parts of separate items of equipment, and

- exposed-conductive-parts of equipment and any simultaneously accessible extraneous-conductive parts, and

- any simultaneously accessible extraneous-conductive parts.

[John Rumm]

Apologies - I have only got the brown version which includes the amendments.

I realise the zones were introduced after the initial version of the

16th (although they are not that relevant to the bonding requirements anyway). Had not realised the inclusion of CPCs came later as well though. Ta for that.

[Geo]

Thanks guys - I think I will add a wire from the shower fused spur connection to both the bath tap pipes.

BTW I took the casing off the shower to see what was earthed inside (just the motor frame) and found a good coating of carbon dust from the brushes all over the guts. Will have to see if new brushes are sold (Mira Event shower).

Next query is how do you connect a bonding wire to 8mm microbore?