Checking continuity of bonding.

[amfisted]

Hi all

Another question about bonding.

Having finished my bathroom refurb and reinstated the bonding straps on the copper water pipes, it occurred to me to examine the bonding cable outside. The cable departs the external meter cupboard, is pinned to the wall for about 3 feet, disappears under the UPVC back door sill and is again pinned along the wall outside the kitchen and bathroom. It enters the wall for the gas pipe bonding in the kitchen ( under the sink) and loops out again, then travels another six feet or so where it enters the bathroom. I had the back door replaced about 2 years ago, and I can't actually see the bonding cable under the new sill. There's expanding foam under there so it should be behind that, but I would like to perform a check to make sure that it hasn't been damaged when the fitter was installing our back door

What equipment do I need to check the continuity of the bonding cable, and how do I use it?

Many thanks in advance

 

[EFLImpudence]

The cable departs the external meter cupboard, is pinned to the wall for about 3 feet, disappears under the UPVC back door sill and is again pinned along the wall outside the kitchen and bathroom. It enters the wall for the gas pipe bonding in the kitchen ( under the sink) and loops out again,

Ok. Is the water supply not there as well - or is it a plastic supply pipe?

then travels another six feet or so where it enters the bathroom.

Is there a metal water supply pipe in the bathroom?
If not then there is no reason for the main bonding conductor to go into the bathroom.

I had the back door replaced about 2 years ago, and I can't actually see the bonding cable under the new sill. There's expanding foam under there so it should be behind that, but I would like to perform a check to make sure that it hasn't been damaged when the fitter was installing our back door

What equipment do I need to check the continuity of the bonding cable, and how do I use it?

You just need a multimeter and a long wire.

You measure the resistance of the conductor - the ohms - from a point on the cable to the Main Earthing Terminal in or near the consumer unit.

Set meter to low ohms.
Measure the resistance of the leads and long wire.
Measure the resistance of the bonding conductor and subtract the resistance of the leads and long wire.
It should be less than 1 ohm. (<1Ω)

 

[amfisted]

Ok. Is the water supply not there as well - or is it a plastic supply pipe?

There is a metal water supply pipe in the kitchen, yes, but if there is bonding on it, its not easily visible. I'll break out my endoscope and have a nose around behind the cupboard.

Is there a metal water supply pipe in the bathroom?
If not then there is no reason for the main bonding conductor to go into the bathroom.

Yes, the mains feed comes up through the floor in the bathroom, and its copper. Pretty sure there's no plastic.

You just need a multimeter and a long wire.

You measure the resistance of the conductor - the ohms - from a point on the cable to the Main Earthing Terminal in or near the consumer unit.

Set meter to low ohms.
Measure the resistance of the leads and long wire.
Measure the resistance of the bonding conductor and subtract the resistance of the leads and long wire.
It should be less than 1 ohm. (<1Ω)

Many thanks for all that, much appreciated.

 

[amfisted]

I’ve had a good poke around behind the kitchen cupboards with the endoscope, and I cant see any bonding on the kitchen water pipework, which is all copper, no plastic.

The CU has RCD and MCB protection.

 

[EFLImpudence]

Yes, the mains feed comes up through the floor in the bathroom, and its copper. Pretty sure there's no plastic.

Then that should be main bonded there in the bathroom so it would seem that it used to be alright.

See if you can find out if it is still connected.

 

[amfisted]

Then that should be main bonded there in the bathroom so it would seem that it used to be alright.

See if you can find out if it is still connected.

Will do, and thanks again for your help.