New house, no main water bonding

[rich.250]

From OSG "There is no requirement to main bond and incoming service where the incoming service pipe and the pipework in the installation are both of plastic. where there is a plastic incoming service and a metal installation within a premises main bonding is recommended unless it is confirmed that any metal pipework within the building is not introducing an earth potential."

IF an IR test between MEt and the metal pipework give a value <22Kohm then the metal internal pipework should be bonded, if it is greater than that then there is no need to bond as it is not introducing an earth potential.

There is some variation in the IR figure depending on who you listen to but generally if it is not connected to earth then there is not need to bond plastic incomers.

Surely an IR test is not the best idea. Introducing unnecessary voltage onto pipe work. Especially if the house is occupied and they are home.

Also the figure depends on the current that is deemed to be safe to touch. 30mA is the max. But most people like to work off 10mA to be on the safe side.
Plus 1000ohms for the resistance of the body.

 

[rich.250]

My 1730 will. I think yours will. What's the max on the cont setting when you turn it on??

 

[ash_s3]

Was going to say! Best make sure they're not in the bath/washing up when doing the test!

 

[Darkwood]

if the property has combi boiler its highly likely unless insulated joints to need bonding as the gas, combi supply earth and water will all be connected together.

 

[ash_s3]

Think it's 99.9Kohms actually

 

[ash_s3]

Yes there is a combi boiler. Will surely need bonding then

 

[rich.250]

if the property has combi boiler its highly likely unless insulated joints to need bonding as the gas, combi supply earth and water will all be connected together.

Good point darkwood. That would certainly bring it down lol.

 

[Guitarist]

Bottom line, bond water unless ALL pipework is plastic. You can argue figures till you're blue in the face but if anything went wrong the question would be "Why wasn't the water main bonded?"

 

[Darkwood]

And agreeing with Guitarist here what happens if the resistance changes in the near future and a fault occurs ?? always best to bond regardless if all copper install.

 

[rich.250]

True true. But if it's over you are just introducing an unnecessary component into the bonding.
I'd rather test it and know I'm doing it right at least. Every install is different.
Just bonding stuff is not a good idea in my eyes and many more.
Each to there own method.

 

[ash_s3]

So why wasn't this picked up earlier?
I'd imagine whole site is the same (50+properties)

 

[rich.250]

I think you'll find that some installers just don't care. Anything to save time and earn more unfortunately.

 

[Darkwood]

True true. But if it's over you are just introducing an unnecessary component into the bonding.
I'd rather test it and know I'm doing it right at least. Every install is different.
Just bonding stuff is not a good idea in my eyes and many more.
Each to there own method.

This could be a generation thing and was how we were taught, although the theory hasn't changed the industry has and RCD's now allow different teaching methods regarding bonding as installations are alot safer... in my day if you said rcd you'd wander what it meant.

 

[rich.250]

Yeh I do agree. If its entirely copper then more than likely it needs it.
Do you see what I mean though, if people are taught to test and see then people would know what needs it and doesn't.
Otherwise we could see people bonding
Anything metal just in case......
And that's just wrong

 

[Guitarist]

True true. But if it's over you are just introducing an unnecessary component into the bonding.
I'd rather test it and know I'm doing it right at least. Every install is different.
Just bonding stuff is not a good idea in my eyes and many more.
Each to there own method.

I understand where you are coming from rich, but if someone has a combi-boiler installed later on, you will get some cross-bonding. If you bond the main properly then the water component won't be a problem whatever happens in the future.