What is wrong with bonding plastic water pipes and plastic gas pipes ?

[Rahi99]

I know once you see plastic entering then you don’t need to bond as it says on site guide.(enters the house plastic then it’s metal)

Would I be in wrong if I have earthed the plastic gas pipes ?
Can someone point me in right direction in on site guide if it’s wrong and why it’s wrong ?

 

[davesparks]

How can you earth a plastic pipe? It's an insulator, you can't make an electrical connection to it!

 

[westward10]

I think you need to elaborate because as above you can't earth something that is all insulated.

 

[timhoward]

My best guess is that he's asking if there's any harm been done if he's bonded the internal pipework at a point that is copper even though it enters in plastic.
The simple answer is no, no harm has been done.

 

[ELECNEWT]

My best guess is that he's asking if there's any harm been done if he's bonded the internal pipework at a point that is copper even though it enters in plastic.
The simple answer is no, no harm has been done.

In the event of a fault to earth, the copper pipe would be raised to the same potential.

 

[GBDamo]

I know once you see plastic entering then you don’t need to bond as it says on site guide.(enters the house plastic then it’s metal)

Would I be in wrong if I have earthed the plastic gas pipes ?
Can someone point me in right direction in on site guide if it’s wrong and why it’s wrong ?

You'd be wasting your customers time and money.

You also have to be careful as, if you're recommending this work when it is unnecessary, you may be acting fraudulently.

 

[Rahi99]

My best guess is that he's asking if there's any harm been done if he's bonded the internal pipework at a point that is copper even though it enters in plastic.
The simple answer is no, no harm has been done.

This is exactly what I mean , so there’s no problem with that ?

 

[Rahi99]

In the event of a fault to earth, the copper pipe would be raised to the same potential.

This is what I don’t understand, can you explain this more please

 

[timhoward]

This is what I don’t understand, can you explain this more please

In the event of a fault to earth, the copper pipe would be raised to the same potential.

Agreed. But that rather assumes the copper pipework is completely insulated already. A combi boiler, an immersion heater, a gas hob with electric ignition etc etc will often create a parallel path between the CPC bar and the pipes.
While it shouldn’t be consciously done, IMHO a mistake in this area doesn’t make an installation inherently dangerous. It’s not as if we get called in every time a copper water main is replaced with MPDE.
(Of course one would also hope that ADS /fault protection would clear an earth fault quickly in the first place)

 

[rewireIT]

It's absolutely pointless. Waste of time and money.

 

[timhoward]

It's absolutely pointless. Waste of time and money.

I don't think anyone is arguing that point. The point he was getting at is whether he's made anything excessively dangerous by bonding some copper pipe when there was a plastic incomer.
Many gas fitters like to bond between every single pipe entering a boiler (even though the boiler itself conducts between them all) and what he did is no more dangerous than what they routinely do.

 

[Rahi99]

Agreed. But that rather assumes the copper pipework is completely insulated already. A combi boiler, an immersion heater, a gas hob with electric ignition etc etc will often create a parallel path between the CPC bar and the pipes.
While it shouldn’t be consciously done, IMHO a mistake in this area doesn’t make an installation inherently dangerous. It’s not as if we get called in every time a copper water main is replaced with MPDE.
(Of course one would also hope that ADS /fault protection would clear an earth fault quickly in the first place)

I just wanna know if I have bonded

Agreed. But that rather assumes the copper pipework is completely insulated already. A combi boiler, an immersion heater, a gas hob with electric ignition etc etc will often create a parallel path between the CPC bar and the pipes.
While it shouldn’t be consciously done, IMHO a mistake in this area doesn’t make an installation inherently dangerous. It’s not as if we get called in every time a copper water main is replaced with MPDE.
(Of course one would also hope that ADS /fault protection would clear an earth fault quickly in the first place)

I just wanna know if I have bonded the internal pipework at a point that is copper even though it enters in plastic is there a problem ? If there is why is there problem ?
Does on site guide mention this ?

 

[timhoward]

I just wanna know if I have bonded the internal pipework at a point that is copper even though it enters in plastic is there a problem ? If there is why is there problem ?

I would say don't lose sleep over it. It's the same situation as if the water supplier changed the pipe to plastic.
We don't try and create extra earthed exposed conductive parts within a property, which you may have done. But there are plenty of other things that may have been earthing the pipes anyway, making it unlikely you provided the only earth connection.

A convoluted example of it being a problem would be if the earthing was TT, and for whatever reason the RCD providing fault protection didn't work. Then if (for example) a toaster had a fault where the casing became live, everything connected to earth in the house would also become live. If pipes had been bonded, they would become live too. So in this extreme (and unlikely) set of circumstances bonding the pipes when they didn't need bonding might have increased the number of surfaces in the house that are live.

Does on site guide mention this ?

The on site guide tells you what needs bonding. It doesn't tell you why you shouldn't bond something and the consequences if you do.
I suspect you are over-worrying about this. Maybe better to just focus on not doing it again?

 

[DefyG]

Tested internal pipework as a matter of routine on a refurb that had had a new plastic water pipe installed.
Pipe work was found to be very low resistance to earth (MET).
Subsequently found a pipe (iron) had previously been installed below ground to an remote building.
Despite incoming main being plastic and the OSG indicating otherwise the internal pipework required bonding!
Always worth double checking!

 

[littlespark]

That’s why it’s worded “extraneous” pipe rather than incoming.
Example there of a metallic outgoing pipe… still extraneous, requires bonding.
Incoming or outgoing. Doesn’t matter.

Plumbers don’t see that… they just assume incoming pipe, needs bonded.