another bonding Q, what would you do?

[brman]

Ok. I know there are lots of bonding questions and I am not about to start another discussion on whether you need to upgrade it to change a light switch but consider this scenario....

Adding a fused (RCD) spur to to a ring to supply the garden. Properly has bonding to gas but not to water (evident by only one bonding conductor into the CU). The catch is that the owner doesn't know where the water stopcock is - he even called in a plumber who could not find it - but he suspects it might be behind some (nicely tiled over) panelling in either the cloakroom, utility room or kitchen.

Would you....
a) insist on pulling the house apart to find the incoming and bond there.
b) bond to the nearest available cold water pipe because it is the best you can find.
c) don't worry guv, I'll pretend I didn't spot it was missing......
?

 

[londonlec]

Option B

 

[londonlec]

Could the water be bonded on the way to the gas meter?

 

[Snapester]

(b) Bond to the nearest point? I don't think they would want me to rip the house to bits just to bond that pipe.

 

[jumpin jax]

Test the pipe to see if it requires bonding first

 

[brman]

Test the pipe to see if it requires bonding first

Good point, I'll do that before I go any further.

Could the water be bonded on the way to the gas meter?

Possibly but probably easier to just run a separate bond to water given what I remember of the house layout.

Glad to see option B is favoured, that was the way I planned to go.

 

[telectrix]

go to plan B. it always works in the movies.

 

[Doomed]

Test, then option b if needed

 

[trev]

My thought is disconnect the gas bond from the CU/MET then get a wander lead with one end on the water and the other on the free end of the gas bond, it may be continuous. If not , you bond the water at the closest point possible and make a note in the CU

 

[EastAnglian]

You might also engage your client in conversation and ask them to think about what they would do if they had a serious leak in the house. If there is no visible stop-cock in the house then they would need to isolate the water supply at the meter presumably. Do they know where this is? Have they checked they can the lid off? Have they confirmed the tap actually turns off? Nothing to do with the job in-hand, but useful 'friendly citizen' type of conversation!

 

[gaz76]

also you could have a look underneath the floorboards, had a few houses where the stop cock was under the floor, personally i would try and find where the water pipe enters the propety and bond it there, after testing to see if it needs bonding of course!!

 

[GLENNSPARK]

look...the bottom line here is that you need to verefy that extrainious-conductive-parts are given adequate bonding here before undertaking any work....thats the way it is....
so.....we can either check to verefy that extrainious (gas and water)..is given bonding to the current edition of BS7671.....or ensure that the bonding in place is still good for continued service......
it would be defeating the object somewhat wouldn`t it....if we bond the gas....but then not the water....(touch voltage).....

 

[brman]

Glenn, agreed, option C wasn't really an option. I know I have to do something. it is just whether I have to do it "by the book" and tear the place apart to find the tap or bond at what is my best guess of as close to the tap as possible.

Customer has already confirmed he can turn the water off in the road if necessary - he is aware of the problem it could cause not knowing where the tap is.

I will indeed test that it isn't really bonded already. if it is then the route of the bonding cable could help pinpoint where the stopcock is which would be nice.
B will be the fallback option if I can't do a better job of locating it than the plumber did.
Either way I reckon I need to add a couple of hours to the estimate to cover the investigation/bonding.

Good point btw of putting a note on the CU if necessary. I would have noted on the cert anyway but something by the CU sounds a good idea too.

 

[GLENNSPARK]

bonding is carried out (ideally) within 600 MM of the incoming supply to a service ......on the consumers side....and before the first `tee`....ideally.....

 

[GLENNSPARK]

low ohms test between the point of entry for the water service and the first point of bonding....

 

[GLENNSPARK]

that is to say the closest point to the incoming service (water) that a BS 951 clamp can be applied......

 

[telectrix]

and maybe a low ohms test between the gas pipework and the water???

 

[Des 56]

Properly has bonding to gas but not to water (evident by only one bonding conductor into the CU).

Perhaps its already done,it makes little sense that someone who is aware of req for gas bond, then omits the water

I would disconnect the gas bond at both ends and continuity test between an end and the water pipes in case its a continuous bond for both

 

[GLENNSPARK]

but wouldn`t you need to confirm that the bonding to both gas and water was continous Tel?.......i.e...unbroken....

 

[GLENNSPARK]

Properly has bonding to gas but not to water (evident by only one bonding conductor into the CU).

Perhaps its already done,it makes little sense that someone who is aware of req for gas bond, then omits the water

I would disconnect the gas bond at both ends and continuity test between an end and the water pipes in case its a continuous bond for both

Dont you believe it Des!!....seen this scenareo quite a bit....where someone has seen fit to apply bonding to one....then not the other??!!

 

[londonlec]

Sorry I meant has the water been bonded via the existing cable to the gas meter.

I feel testing the water pipe with the low ohms method will be a waste of time due to parallel paths via appliances.

 

[hoppy]

When you guys do a low ohm test between wo points, is that just to ensure the resistance between them is less than 0.05 ohms, and if above then bonding is required?

 

[Des 56]

If the gas bond is what it says on the tin,disconnecting both ends will ensure that a continuity test of that cable to the water pipe will determine one way or the other, whether it includes the water pipes or no

 

[brman]

Dont you believe it Des!!....seen this scenareo quite a bit....where someone has seen fit to apply bonding to one....then not the other??!!

Indeed. In fact my own house was bonded to the water but not the gas. Despite the fact they were only 2 feet apart! One of the many bodges done on the electrics by a kitchen fitter......

It could be that the gas bond does go via the water incoming but, from a quick look, it looks like it goes direct, I'll need to test it properly to be sure though.

 

[GLENNSPARK]

its like this.....inspection always precedes testing....so you would need to confirm that the bonding cable that has been used to bond either the gas or water pipe is continuous.....that is to say that it goes to the gas (point 1)....where the insulation has been bared off (in order to connect to a BS951 clamp) but without cutting the conductor....then goes to the next point...water (point 2)......otherwise you will need to either heat shrink and through crimp (to regain continuity)...or pull a seperate bonding conductor to point 2......