OSG, bonding plastic pipes etc etc

[magnoliafan89]

Hi all

Having a thumb through the OSG and on section 4.5 Main protective bonding of plastic services, it says there is no need to bond an incoming service of the service pipe is plastic....thats kind of a given....my struggle lies on the next page;
"Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that anu metallic pipework within the building is not introducing Earth potential"

Is there a way of determining if there could be an earth potential?
I may be asking a really simple question and be mortified by stupidity but at this moment in time im lost. If a house is supplied with plastic services incoming but then throughot the dwelling it is metal pipes...whats the score with bonding?

Cheers in advance

 

[Richard Burns]

Conductive parts in the vicinity of the electrical installation but not part of it are not required to be earthed because the regulations require that the risk of electrical contact is addressed and minimised.

An exposed conductive part, i.e. one which is an integral part of the electrical installation, accessible to touch and may become live under fault conditions, is required to be earthed.

Bonding would be required to conductive parts likely to introduce an external potential into the installation.

Neither of the above two cases is applicable to metal parts accessible to touch that are not part of the electrical installation.

 

[HandySparks]

Neither of the above two cases is applicable to metal parts accessible to touch that are not part of the electrical installation....

... and not extraneous.

 

[EalingBadger]

Some of the above posts seem to miss the point that if internal metal pipework is connected to metal taps (etc), then it needs to be earthed. If the 22k ohm or the 5 Meg ohm pipeworks got shorted to the phase conductor then the 22k would trip the RCD (if fitted on old installations) but the Meg ohm pipework would sit at 230 volts - a real hazard. As I understand the situation, bonding is only not required when all touchable metal parts (taps, sinks, radiators) are only connected by insulated fittings (or pipework). Otherwise it should be bonded. Proper bonding at the boiler (water, gas or oil pipe) is probably best.

I thought the current advice was that kitchen sinks most definitely do NOT require bonding.

Seems a bit counter-intuitive I'll grant, but that is my understanding of the latest solid advice on the subject.

 

[EalingBadger]

My brother-in-law is a Gas Safe engineer and he is adamant that plastic gas pipes coming out of the ground have to be converted to metal (usually barrel) before they emerge - the reason for this being that plastic is not considered mechanically, UV, or thermally (think extraneous applied heat from the sun or open flames (well, it is gas pipe!)), robust enough.

Thus the (metal) gas meter and therefore any metal pipework connected to it on the consumer side will be at local earth potential.

MDPE pipe is only UV resistant in black. Potable water is blue - but for internal or underground use only, and gas is always yellow.

 

[Midwest]

I thought the current advice was that kitchen sinks most definitely do NOT require bonding.

Seems a bit counter-intuitive I'll grant, but that is my understanding of the latest solid advice on the subject.

I think your 'current advice' was actually a few decades back.

Naah that's definitely a have.

 

[EalingBadger]

I think your 'current advice' was actually a few decades back.

Really?

Happy to be corrected, but I am pretty sure that I saw this on one of the web sites like voltimum.co.uk in recent months...?

Here is just one reference:

IET Forums - Kitchen sink bonding - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=32335

but I'm sure I have seen it elsewhere as well.

 

[robd]

I was having a butchers round some new show homes recently. On the CU was a printed label, that said words to the effect, water service plastic, internals plastic, therefore water not bonded. Don't know why they chose to share that with everyone?

They've probably been pulled in the past by a jobsworth from an office so did it to save about a million emails and phone calls to try and explain why.....been there had that

 

[EalingBadger]

I think your 'current advice' was actually a few decades back.

Naah that's definitely a have.

Ah, I see what you mean now (I think!) - the advice is not new but it remains current.

 

[Midwest]

Really?

Happy to be corrected, but I am pretty sure that I saw this on one of the web sites like voltimum.co.uk in recent months...?

Here is just one reference:

IET Forums - Kitchen sink bonding - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=32335

but I'm sure I have seen it elsewhere as well.

Have you read your link?

 

[EalingBadger]

Have you read your link?

Yes - briefly reminded myself of what it said again today but first read it ages ago.

I am guilty of too broad a brush stroke with the "NOT" in my first post. Of course, it should be "may not" - the possibility of metal waste pipes and all that should be taken into consideration.

(I love a bit of pedantry - as long as it is not me on the receiving end of it of course. )

 

[johnduffell]

I thought the current advice was that kitchen sinks most definitely do NOT require bonding.

Seems a bit counter-intuitive I'll grant, but that is my understanding of the latest solid advice on the subject.

Maybe, but if you replace the word "bonding" with "connecting to one side of the electrical installation (that's hopefully close to local earth)" and the word "sink" with "a large piece of touchable metal" then it seems a lot less counter intuitive.

 

[Midwest]

They've probably been pulled in the past by a jobsworth from an office so did it to save about a million emails and phone calls to try and explain why.....been there had that

I'd just made a note in the EIC.

As a new home owner, I don't really want to see a 'fuse board', especially one covered in labels. Just saying.

 

[Midwest]

Yes - briefly reminded myself of what it said again today but first read it ages ago.

I am guilty of too broad a brush stroke with the "NOT" in my first post. Of course, it should be "may not" - the possibility of metal waste pipes and all that should be taken into consideration.

(I love a bit of pedantry - as long as it is not me on the receiving end of it of course. )

I do try not to be excessive about detail, not a good trait.

As someone who spent ages under metal kitchen sinks, trying to attach a conductor ('cos the plumbers didn't care sparks had to then), I was rather glad it ceased, along with earthing ali windows & garage doors. But that went out in the 1980's (15th Ed?). I would of thought that would of been long since forgotten about. Like researching something, without using Google

 

[DPG]

I still bond my upvc windows. Just to be safe.

 

[robd]

I'd just made a note in the EIC.

As a new home owner, I don't really want to see a 'fuse board', especially one covered in labels. Just saying.

I know but when the plumber turns up to service the boiler and notes that the service isn't bonded and you have 4 phone calls 3 emails and in the end a visit to take your own picture to send to prove your point you wish there was a million stickers on the board instead, speaking from experience like