Bonding central heating pipes

[AP Electrical]

Cross bonding central heating pipes, good practice to wire in 4mm2 ?
any thoughts...

 

[malcolmsanford]

Are these pipes in a special location, and are they an extraneous conductive parts. If yes to both and there is no RCD protection or main equipotential bonding on the main incomers then yes you can bond with 4mm or 2.5mm if there is mechanical protection.

 

[IQ Electrical]

I'm trying to remember when it was last a requirement to 'cross-bond' heating pipes....

I'm also trying to imagine a scenario where central heating and hot water pipes would be classed as an extraneous-conductive part (assuming domestic).

 

[AP Electrical]

Thanks malcolm, kitchen and rcd protected, going to go with 4mm as I've got some in the van!!.

 

[AP Electrical]

I'm trying to remember when it was last a requirement to 'cross-bond' heating pipes....

I'm also trying to imagine a scenario where central heating and hot water pipes would be classed as an extraneous-conductive part (assuming domestic).

From what i can gather it's a grey area so thought better to ask !!!

 

[MarkieSparkie]

Hi Alex,
Electricians view:
Main protective bonding conductor to incoming water service pipe required, there is no specific supplementary bonding requirement for metallic boiler pipework in BS7671.
Supplementary Bonding is only necessary if the continuity between the MET and boiler pipework exceeds 0.05 Ohms. Usually the pipes are combined into a steel manifold which provides adequate continuity.
Gas fitters view:
I believe the latest Gas Regs still stipulate that boiler pipework should be supplementary bonded ... hence the widespread and unnecessary misuse.:66:

 

[telectrix]

i would first determine whether you should be bonding the pipes anyway.

 

[Chr!s]

I'm trying to remember when it was last a requirement to 'cross-bond' heating pipes....

I'm also trying to imagine a scenario where central heating and hot water pipes would be classed as an extraneous-conductive part (assuming domestic).

It may be where a potential other than earth potential may be introduced.

 

[AP Electrical]

Mate who i'm doing it for is a gas fitter - sounds right the main gas/water bonding is around 2 feet away all copper pipework, told him I didnt think required as visible continuous earth path but he say's looks better to do it and customers like it - well he's paying the bill.

 

[malcolmsanford]

Then just string some pretty Yellow/Green wires across the pipes and not terminate to an earth if that is their whim. But as Mark said the gas regs do like to bond everything metal that don't move, but be honest they are plumbers after all.

 

[IQ Electrical]

The 'gas reg's' only mention the main bond to the gas service, the problem seems to come from the boiler manufacturers instruction leaflets which in the vast majority of cases, seem to mention 'earth bonding all boiler pipework'.

This takes us through to 510.2 adherance to manufacturers instructions-a slight anomoly!

 

[Chr!s]

Gas Safety (installation and use) Regulations 1998

Safe use of pipes


Section 2

(2) Any person who connects any installation pipework to a primary meter shall, in any case where equipotential bonding may be necessary, inform the responsible person that such bonding should be carried out by a competent person.

And that's your lot.

If the manufactures require it, install it, If not work to BS7671.

Chris

 

[Deleted member 26818]

I only ever do this if instructed to.
Whan I do it, I link the bands of the earth clamps together by passing the end of the first one through the next and so on.
I then attach the earth conductor to just one of the clamps.

 

[AP Electrical]

Job done, replaced fcu and installed RF thermostat and told him pointless crossbonding as main gas/water bond was literally inches away, seemed confused scratched his head and said you've lost me, then walked off - typical gas fitter then!!!

 

[Deleted member 9648]

I only ever do this if instructed to.
Whan I do it, I link the bands of the earth clamps together by passing the end of the first one through the next and so on.
I then attach the earth conductor to just one of the clamps.

Seem to recall reading somewhere that this was not permitted,as it was not possible to confirm that the minimum size of bonding conductor was used....seems picky though,I wouldnt have a problem with it.