Earthing Central Heating / Hot Water

[AlanPartridge]

Hi all,

First of all sorry for these questions but i've been searching and reading posts for 2 hours and not really got myself a confident answer.

In my house i have installed a Combi Boiler and 5 radiators as it only originally had a hot water boiler upstairs.

I have basically done all the pipework and installation ready for a Gas Man/Electrician to obviously do the gassing/electrical work and pass the whole thing...

Currently as you can hopefully see from the picture, there is a 6mm earth cable running from the CU (top of the picture), down the back of the board and it loops onto the earth strap on the gas pipe then onto a cold water pipe near where the cold water comes into my house.

I now need to earth the Hot Water and the Central Heating so;

How is it best to do this and should i really even be attempting it? (bearing in mind it will all be checked appropriately before testing anyway)

In the picture (Circled in red) there is what appears to be a spare earth connector... Can i run a 6mm earth cable from this spare point to the hot water pipe and loop it onto the central heating pipes in a similar way. If so do i need to link it across the flow and the return pipes or just one of them and should it be done at a certain point in the system?

Sorry it's so long but i like to try and explain everything fully.

Any suggestions are much appreciated as always..

Cheers

 

[Lectrician]

OK - the cent heat and hot water pipes only require main equipotential bonding if they are an extraneous conductive part - a metal part that leaves the equipotential zone (AKA : the house).

It is a very 'wide open' regulation with regard main eq bonding to cent-heat/air-con. the reg is hugely open to interpretation. I always take it as meaning these only need bonding if they leave the eq-zone.

The gas and water pipe, which do leave the house, require main-eq bonding. This should be done in 10mm for a TN-S or TN-C-S earthing arrangement (yours is one of these - 99.99% for sure).

You should also make sure that where the cable is taken to the gas, and then to the water, that it is done without chopping it. This means the cable leaves the CU, is 'wrapped' around the terminal on the gas bonding clamp, and carries on to the water.




Drunk a little too much this evening - does it make sense?

 

[AlanPartridge]

lol... Thanks for your quick reply, yeah that makes perfect sense.

It probably is actually 10mm not 6mm as you say, i was guessing before but looking again it's definitely bigger than 6mm.

And YES it does loop onto the cold water without being cut because i actually just replaced the clamp with a new one as it was very very rusty...

That's fair enough then that it's not necessarily required but from a safety point of you would you recommend doing it anyway.

Basically the house is in a mess at the mo with floorboards up everywhere so nows the time to do it if i'm going to...

 

[Adam_151]

This means the cable leaves the CU, is 'wrapped' around the terminal

rather than wrapping around, another way I have seen is to remove approx 20mm of insulation, separate the strands with a screwdriver, and put the screw that secures it to the clamp through the middle of it.

Drunk a little too much this evening - does it make sense?

lol, about to start on the drink soon myself

 

[AlanPartridge]

Thanks for the replies.

Would you recommend earthing them anyway though for safety purposes?
Also, would it be ok to loop one run from that earth point pictured in Red to a hot pipe a flow pipe and a return pipe as long as it wasn't cut, if it was continuos and just wrapped around the straps.

Cheers everyone...

 

[kai]

The earth looks like it emerges out of the side of the black service fuse block (correct me if I am wrong), this is probably a TNCS/PME system, for which 10mm bonding is requred as a minimum size.

 

[Biggles..]

when the gas man arrives he should or ask you to bond , all the pipes on the underside of the combi together, by doing this in effect you have bonded gas, hot, cold and central heating and the blow off pipe work. electricians will argue that the 16th doesn't say this, and that the 15th now obsolete we know. This is requirement by corgi and they always win when it comes to gas even if the regs say different.

 

[securespark]

rather than wrapping around, another way I have seen is to remove approx 20mm of insulation, separate the strands with a screwdriver, and put the screw that secures it to the clamp through the middle of it.

I found that OK on the 15th with 6mm2, but with 10, it is a struggle.

 

[Lectrician]

Bonding pipes beneath the boiler has never been a requirement of the IEE or CORGI. It's cowshit!

Main Eq to gas, water WITHIN 600mm OF ENTERING BUILDING/STOP COCK.

Anything else, other that supp in bathroom/shower room is beond what is required, and a gas man asking for so would wind me to the point of telling him to **** off.

 

[securespark]

Not saying it's right, Lec, but I've been asked by many a landlord to cross-bond at the boiler because the LA have pointed it out as a potential failure in a rented property!!

 

[Biggles..]

Like i said in my post i know bonding pipes under boilers are not in the regs however it is mentioned on every visit by all corgi inspectors.next time mine comes i shall quote lectrician and tell him its cowshit and to f*** off.Will make me feel better but wont gain the customer anything because he'll fault the installation.

 

[AlanPartridge]

Wow, what have i started here...

Thanks for all the replies, Just to recap then... I would be ok to run the earth and loop it around the pipes back to that earth point, as long as it's done in 10mm Earth cable.

Thanks again for all your help everyone, much appreciated.

 

[Biggles..]

Main equipotential bonding to the gas and water should be done in 10mm (for PME)seperate pieces or 1 continuous length, under the boiler is supplementary bonding, join all pipes using 1 continuous length of 4mm.Thats what we do under boilers and keeps the guy from the kennel club happy.

 

[AlanPartridge]

Cheers lcgs, thanks for your time everyone...

All much appreciated.

 

[mikely]

As Kai has pointed out, what you have circled in red looks like the earth from a PME service fused cut out, in which case this is the main earth terminal, not a spare earth connector. This would then be connected into your consumer unit but does not appear to be. Alternatively, you may have a TT installation earthed via an earth rod, in which case, your bonding connections should not be made to the earth terminal you have highlighted. This IEE article should help identify what you have:
http://www.iee.org/Publish/WireRegs..._matters_earthing_your_questions_answered.pdf

If at all uncertain, you should get an electrician in to sort out your bonding (and possibly earthing).