To cross bond or not to cross bond

Under the current U.K. regulations is it still neccessary to cross bond pipework below every sink in an installation

Metal pipework under a sink which connect to the taps have to be considered under BS7671 as 'Extraneous conductive parts', therefore, bond them!

On second reading you state 'every sink',
If you have a line of sinks in a public toilet for example you would not need to cross bond under each, you would however need to make sure that they are bonded such that there is no potential difference between any mutually accessible conductive parts.

thank you sparkyman thats exactly what I thought

Commercial & Domestic kitchens, cloakrooms, bedrooms and toilet areas which may contain a sink or hand basin but do not contain a bath tub or shower are not among the special locations covered in Part 6 of BS 7671. There is usually no reason why such rooms should be considered as locations of increased electric shock risk requiring the provision of supplementary bonding.

The 15th Edition of the IEE Wiring Regulations required supplementary bonding to be applied to all sinks where extraneous-conductive-parts were not reliably connected to the main bonding, and many examples still exist today. This requirement was deleted in subsequent editions of the Wiring Regulations and it is not required by the present Standard, BS 7671.

Alan

Suggestion: Essentially, all conductive metallic surfaces are safer to have them bonded since not all of them (not all items) are explicitly covered in standards.

jbartos,

Try telling that to the window cleaners who have been killed by the touch voltage appearing on earthed metal window frames

Things like window frames, in particular, which are likely to be at the edge of the equipotential zone really should not be bonded.  Where there is doubt, the if an insulation resistance ("Megger") test shows that it is at least 2Mohm to earth, then don't bond it!

Otherwise, you'll have to start bonding door handles, coat hooks, etc!

Brian