Bonding Central Heating copper pipes.

[rezarf]

Earthing copper pipes for a central heating system.

I've been trying to get my head round this here is the CH pipework

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• rezarf
• 4 Apr 2008
• 2

and here is what I have got to do the job

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• rezarf
• 4 Apr 2008
• 1

I have x3 15mm and x3 22mm copper rings and x5 adjustable copper things.

Rezarf

 

[ban-all-sheds]

What do you mean by "earthing" them?

Why do you think they need earthing?

Do you mean bonding?

Main or supplementary?

Where is the boiler?

Why are you using second-hand cable and clamps?

 

[rezarf]

i'm not sure of the exact term but I was told that all the pipes would have to be tied to earth.

Bonding??

Not sure about main or supplementary but the power for the boiler comes from a 'spur' connected to main power supply.

The boiler is located upstairs in a cupboard. That was the cable and clamps that were there from the old system. I will get new cable and clamps if needed. The copper parts are all brand new.

hope some of this makes sense.

 

[rezarf]

ok read into it a bit more and yes I want to bond the central heating pipes to the earth circuit.

from what I have read the pipes should be earthed as close to the earthing block as possible.

In my case I should bond them downstairs somewhere closer to the earth block.

Am I better using a bonding clamp ther same as used for kitchen taps?

Rezarf

 

[gas4you]

Cross bond all under the boiler with standard bonding clamps. The gas and cold water should already be main bonded to the earthing block.

Use new clamps and cable

 

[ban-all-sheds]

i'm not sure of the exact term but I was told that all the pipes would have to be tied to earth.

"Tied to earth" is main equipotential bonding, and it is done to incoming service pipes.

So if upstairs in the cupboard is where your gas and water pipes enter the house then you will need to run a 10mm² cable from each back to the main earth terminal, or a single continuous one. If it's a long way to the MET you might consider using 16mm².

If that's not where the gas and water pipes come into the property then there is no need to run any cables back to the MET, and those services should already be bonded.

Not sure about main or supplementary but the power for the boiler comes from a 'spur' connected to main power supply.

Supplementary equipotential bonding connects together all extraneous-conductive-parts and the earth conductors of circuits in bathrooms and shower rooms etc. If you haven't got plastic pipes, and the CH supplies a radiator in the bathroom then the pipes for that and the radiator need to be connected to the circuit earth(s) with 4mm² cable.

If you don't have a bathroom in the cupboard then there is no need to connect the pipes to each other, or to anything else, however, if the cupboard is close to the bathroom then you might elect to connect the bonding cables in there as it may be easier and look better.

I will get new cable and clamps if needed.

Good idea - particularly with the clamps, as they don't have the required safety labels.

 

[ban-all-sheds]

Cross bond all under the boiler with standard bonding clamps.

Why?

 

[mikej2005]

rezarf - Worcester Bosch have a useful PDF that shows their recommendations for bonding :

http://www.worcester-bosch.co.uk/cache/file/24/equipotential-bonding.pdf

 

[ban-all-sheds]

Interesting that that document should say you need to take a main bonding cable from the CH pipes to the MET, and then not show it in the diagram....

 

[mikej2005]

Interesting that that document should say you need to take a main bonding cable from the CH pipes to the MET, and then not show it in the diagram....

If the water and gas pipes are bonded to the MET as shown and the pipes beneath the boiler are bonded adequately, would that not amount to the same thing ?

 

[ban-all-sheds]

Now there's a thing. If it does, then take a look at that great big metal manifold linking all the pipes together...

 

[rezarf]

Now there's a thing. If it does, then take a look at that great big metal manifold linking all the pipes together...

..

that doesn't link them together that is an pipe that you can use to to refill the system with water, it only connets 2 pipes.

 

[GaryMo]

Now there's a thing. If it does, then take a look at that great big metal manifold linking all the pipes together...

..

that doesn't link them together that is an pipe that you can use to to refill the system with water, it only connets 2 pipes.

Hahaha, classic!
That's a filling loop and not what BAS meant
The part he means is the metal plate at the very top of the picture, more of a gland plate than a manifold though.

 

[SeanT]

The gas one may not be electrically connected to the other pipes in all cases, but the incoming water one certainly will, as you say by the rather large unit attached to the wall! - unless the incoming water main goes metal - plastic - metal that is....

 

[GaryMo]

As long as all incoming services that can introduce a potential have MEB conductors as they enter the property and supplementary bonding has been carried out to pipework and circuits within a shower or bathroom then there's no need to worry about cross bonding under the boiler.