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......
?

 

[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......

 

[Knobhead]

Use option B.

Have a read of this http://www.electriciansforums.net/e...al-regulations/46129-just-start-argument.html I have proved the regulations aren’t always right. Copper pipe has a higher conductivity until some cheapskate puts plastic in.

All you can do I make the installation as safe as possible. You could install a new CU all bonding correct at the time of installation. What of the future?

You need a holistic helmet to know what’s behind a wall or what may happen in the future. (I’ll rent my helmet out at £1000 per hour).


View attachment 11445

 

[GLENNSPARK]

all i am saying here though Tony....is that inspection precedes testing.....if you cant inspect for any valid reason...then go to testing....after all inspection proves the things you can see......testing proves the things you cant......

 

[Knobhead]

Glen, I know what you on about.

There’s a lot to be said for the old method of cross bonding. Better still ban plastic pipe and train plumbers to solder copper pipe. Plumbing is like putting Skittle Sticks together now.

(Showing my age with Skittle Sticks, I was about 10/12 when they first came out).

 

[GLENNSPARK]

No probs Tony.

 

[brman]

thought I might as well report back as I have just checked this house again. Gas bond goes to gas only. No other bonding back to the CU.
However a check of the cold water pipe at the nearest point to the CU gives 0.04 ohm. (but with the gas bond in place though)

I didn't have time to remove the gas bond and test properly but there is a visible cross bond between the hot and cold water under a sink so I am pretty sure it is being bonded from the gas, through the boiler to the hot water then to the cold water via this bond.

I will be suggesting a new bond to the cold water at the nearest point which just happens to be about 6 feet from the CU and very easy to get to so there is little reason not to.