Does this pipework need bonding?

[springcrocus]

A new combi boiler has been fitted in a purpose-made cupboard in the upstairs bathroom to replace an ageing coal-fired back boiler. The existing gas supply runs from the meter box about two feet along the outside wall before going through the wall and under the kitchen floor to the gas cooker. The gas pipe is correctly bonded in 10mm G/Y about six inches above the floor.

The heating engineer has chosen to replace the elbow where the gas enters the building with a tee, and extend the pipework along and then up the outside of the building before diving through the wall at first-floor level, thence to the boiler. Therefore, the gas enters the building at two separate points.

The electric supply is TNC-S, the earthing conductor is 16mm, and bonding to the water is 10mm. All pipework is copper with soldered joints.

An electrical supply is required to power the boiler and will be taken via a fused spur unit from the upstairs ring.

Now the question. Does the new gas pipe in the bathroom also require bonding? (And why, or why not).

 

[binky]

Do you have RCD protection for all circuits, if not, then cross bonding boiler is required.

 

[ParkySparky]

Do you have RCD protection for all circuits, if not, then cross bonding boiler is required.

+1

 

[binky]

Forgot to say, if you do have RCD protection for all circuits, then bonding may not be rquired provided it meets certain criteria. Someone trying to charge you big money for this Springy? FRom what you have described second gas bond after new tee is not required unless done in plastic which would contravene gas regs.

 

[Nicky Tesla]

-1

 

[steptoe]

Do you have RCD protection for all circuits, if not, then cross bonding boiler is required.

why?

that has never been an electrical reg AFAIAA, if it has, what one, and when?

 

[binky]

-1

why?

 

[steptoe]

why?

prob cos you edited/got another post in but still wrong info

 

[Nicky Tesla]

Cross bonding poss not required, just check continuity from one pipe to another before any bonding is put in place. Cross bonding boilers is a plumbers trick. I know it is in a bathroom but then again it is not, as it will be in a cupboard.

The gas bond should by rights be made before the tee, but in my opinion it is the job of the gas man to do if he is from another company than yours because he has caused the need for the bond to be moved.

 

[binky]

See what you mean, most modern boilers have plate between pipes that cross bonds everything anyway, but I'm still in the habit of doing it to save customers from hassle by idiots "your boiler ain't safe it aint bonded missus"

---------- Post Auto-Merged at 23:01 ---------- Previous post was made at 22:59 ----------

why?that has never been an electrical reg AFAIAA, if it has, what one, and when?

yep your right Steps, it's a plumbers requirement, so funny how so few like doing it...

 

[steptoe]

sorry binky, that came across wrong, ,

AFAIAA any boiler that complies with BS does not require separate cross bonding, the manifold must ensure that to comply with BS. so no-one needs to cross bond it,

its a rule made up by numpty inspectors

 

[springcrocus]

Cross bonding poss not required, just check continuity from one pipe to another before any bonding is put in place. Cross bonding boilers is a plumbers trick. I know it is in a bathroom but then again it is not, as it will be in a cupboard.The gas bond should by rights be made before the tee, but in my opinion it is the job of the gas man to do if he is from another company than yours because he has caused the need for the bond to be moved.

Bonding BEFORE the tee would, therefore, be external.

The new pipe in the bathroom is an extraneous conductive part. The question is, does it (also) require bonding.

 

[SLIPSHOD & SLAPDASH]

It sounds like the boiler is having a cupboard made to fit around it. My view is this is still within the bathroom. If so & there is no RCD protection then cross bonding is needed between the boiler and all circuits within that room. If you want to be entirely correct with the (main) bond to the gas this should be done at the point of entry, in this case maybe at the two points, or at the T or at the meter, which for us is not really correct but all gas engineers cry if its not.

 

[springcrocus]

If you want to be entirely correct with the (main) bond to the gas this should be done at the point of entry, in this case maybe at the two points, or at the T or at the meter, which for us is not really correct

That, Slips, is what I was hoping people would discuss. Is it correct to (main) bond at two separate points on a single service? Or is it correct to rely on the original bond even though, effectively, the service leaves the building at one point and re-enters at another?

 

[binky]

No harm in doubling up, external bond is acceptable provided a suitable outdoor clamp has been used (blue not red). From a conductivity point of view, 20mm copper pipe has shed loads of copper in it and therefore provides a much bigger CSA than 10mm copper wire. If you think about it there is only one path to earth, ie into ground, even if pipe pops in and out again

 

[Manator]

Now that the forum is under new management I may write a few articles to lay aside a few myths about earthing and bonding.

That is IF the new management will allow me to do so.

 

[springcrocus]

I wish you a good audience, Manator, but I wonder if you will be performing to an empty theatre. I was hoping to promote a bit of discussion but it seems I was trying to float a lead balloon.

Ah well, back to one-liners.

 

[ADS]

Hi Springcrocus,

The only question you have to ask yourself is does the gas pipe, (where it re-enters the building), fit the definition of an 'Extraneous Conductive Part'.................in other words, does it introduce a potential, 'earth' or otherwise, to the building.

That's it.....simple.

If it does - bond it.

If it doesn't - don't bond it.

Extraneous Conductive Part - A conductive part liable to introduce a potential, generally Earth potential, and not forming part of the electrical installation.

 

[steptoe]

Hi Springcrocus,The only question you have to ask yourself is does the gas pipe, (where it re-enters the building), fit the definition of an 'Extraneous Conductive Part'.................in other words, does it introduce a potential, 'earth' or otherwise, to the building.

That's it.....simple.

If it does - bond it.

If it doesn't - don't bond it.

Extraneous Conductive Part - A conductive part liable to introduce a potential, generally Earth potential, and not forming part of the electrical installation.

ah, good point,

and, does it now form part of the electrical installation now you have bonded it at a seperate location?

 

[Manator]

I wish you a good audience, Manator, but I wonder if you will be performing to an empty theatre. I was hoping to promote a bit of discussion but it seems I was trying to float a lead balloon.Ah well, back to one-liners.

On the contrary I think you have raised a good point, however the fact is that a simple test can answer that question.

Earthing appears to be some kind of mystery for quite a few electricians, but there is nothing magical about earthing, it is part of the whole picture. BS7671 is in my opinion a very small part of a much bigger picture, and at best an idiots guide to electrical installations. Some of our learned friends on this forum will agree with that, as they have to work to standards that are far more detailed than BS7671.

Some standards that I work to are in contradiction with BS7671, but are never the less compliant (overly so).