Water bonding on a PIR

[peter1992]

When carrying out a PIR do you actually have to see the earth clamp on the water pipe?
I've had a few jobs lately where only the stopcock can be seen at the back of the kitchen cupboard and everything else is boxed in. I check continuity from the stopcock back to the CU and that is ok, but do I actually have to physically see the clamp? I know the regs say that bonding has to be within 600mm but this will mean pulling the kitchen cupboard to bits.

 

[telectrix]

the clamp should be accessible for inspection. i'd give it a code 4 at least, maybe even a code 2.

 

[Richard Burns]

I find the same thing, I make a note that continuity is OK but clamp inaccessible.
I would say code 4, real nuisance to us but not to any one else!

 

[MarkieSparkie]

I find the same thing, I make a note that continuity is OK but clamp inaccessible.
I would say code 4, real nuisance to us but not to any one else!

Yes, same here.

 

[Deleted member 9648]

As the others state....not visible will get a code.
The problem with relying on a continuity test is that with parallell paths you may get a perfectly good reading even if the bonding is not present.

 

[miner69er]

i don't give it a code provided the continuity test is less than the stated maximum of 0.05 ohms (as per guidence note 3, 612.2.1) and make a note on the paperwork that the connection was not visible or accessible

 

[rdelectrical]

hello would a potential difference test achieve whether water pipe bonded if a clamp cannot be seen

 

[Richard Burns]

Not sure what you mean by a potential difference test, if you are referring to a continuity test then, as stated above, parallel paths through other bonding and by misidentification of the bonding conductor may invalidate the result but in general if there is a low resistance to the water it is bonded but maybe not according to the regulations.

 

[rdelectrical]

hi what i meant was if you used a voltage tester and placed one probe onto a live and the other onto the water pipe if you get a pd of 230 volts doesnt that mean the pipe has a pathway to earth
thanks for your reply

 

[Deleted member 9648]

hi what i meant was if you used a voltage tester and placed one probe onto a live and the other onto the water pipe if you get a pd of 230 volts doesnt that mean the pipe has a pathway to earth
thanks for your reply

You are missing the point of bonding....incoming services need to be bonded because they already have a path to earth,not because they dont....this is why tests are unreliable as a means of confirming bonding,and why it needs to be visible for inspection.

Incoming services may introduce an external earth potential into the building.During fault conditions conductive parts within the building may be subject to a rise in potential relative to the general mass of earth untill the protective device clears the fault. Anyone in contact with a conductive part under these conditions may be at risk of a shock,in practice that person is likely to be insulated from the general mass of earth by virtue of being stood on an insulating floor..(wood,dry concrete etc)...so the risk is minimal.
However incoming metallic services effectively introduce the general mass of earth into the building,now anyone in contact with a conductive part at the same time as an extraneous conductive part during the fault will receive a serious shock....by tying conductive and extraneous parts together by bonding there can be no potential difference between them and a reduced shock risk.
Remove from your grey matter the notion that bonding is earthing the pipes,it is an entirely different thing.

 

[rdelectrical]

many thanks for your reply you have pointed out to me something i knew but but hadnt thought of i over looked the obvious
your info has given me a greater insight and more working knowledge