Cross bonding Boiler pipework in a kitchen what conductor size do I need?

Question

Hi Guys, I'm cross bonding some metal pipes coming out of a boiler I just need to know what what earth conductor size i need to use?? the main equipotential bonding with the gas and water mains is done but these for some reason havn't been done. anyone know

Thanks in advance

Answer 1

10mm

Answer 2

4mm G/Y single earth cable + earth clamps

Answer 3

BS7671 says 2.5mm. If you do it, you should take the bonding into the cpc of local circuit supplying the boiler too.

NICEIC sez 4mm

Answer 4

use the same size as the rest

Answer 5

Water in itself is one of the best conductors of electricity, and it definitely goes directly to ground, why would water lines need to be grounded or bonded? Run in metal pipes also does their own bonding to earth.