Earth bonding after boiler move

[adaml]

Recenty had a boiler moved. In the old location there was earth bonding to the pipes. After the move there is a few metres of plastic pipe seperating the boiler and the central heating feed and return. So the situation now is the central heating throughout the house has no bonding. Should the remaining loop of pipes/rads which are isolated from the boiler by the plastic pipe be earthed?

If its important there is bonding to the gas meter, water main and cold feed in bathoom. Its just the main chunk of CH which no longer has it.

 

[SUNRAY]

Recenty had a boiler moved. In the old location there was earth bonding to the pipes. After the move there is a few metres of plastic pipe seperating the boiler and the central heating feed and return. So the situation now is the central heating throughout the house has no bonding. Should the remaining loop of pipes/rads which are isolated from the boiler by the plastic pipe be earthed?

If its important there is bonding to the gas meter, water main and cold feed in bathoom. Its just the main chunk of CH which no longer has it.

The boiler should have at least 1 metre of metal pipework before going into plastic.

 

[EFLImpudence]

It is not he purpose of '"bonding" to "earth" metal parts.

Bonding - joining electrically - is to equalise potential (in the event of a fault) of parts which are already earthed.


If your central heating pipes now have no connection to earth then they do not require bonding.

 

[adaml]

s it is copper for a couple of metres then changes to plastic.

Forgot to mention that, yes its copper for first couple of metres until its in the floor void.

 

[adaml]

It is not he purpose of '"bonding" to "earth" metal parts.

Bonding - joining electrically - is to equalise potential (in the event of a fault) of parts which are already earthed.


If your central heating pipes now have no connection to earth then they do not require bonding.

Thanks for the explanation.

 

[SUNRAY]

It is not he purpose of '"bonding" to "earth" metal parts.

Bonding - joining electrically - is to equalise potential (in the event of a fault) of parts which are already earthed.


If your central heating pipes now have no connection to earth then they do not require bonding.

Yes that just about sums it up...
except that during a gas inspection by Gas safe engineer it will be highlighted as incorrect as they work to different rules.

 

[JohnD]

I believe the boilermen work on the principle that if you have a number of metal pipes, and a metal boiler, any one of which MIGHT be fixed to something with an electrical fault, and any of the others MIGHT be earthed, it is wise and safer to have them all bonded to each other.

The boilermen are particularly likely to cut, disconnect and handle wet pipes that might otherwise have provided adventitious bonding.

 

[EFLImpudence]

Yes that just about sums it up...
except that during a gas inspection by Gas safe engineer it will be highlighted as incorrect as they work to different rules.

...because they do not understand the fundamental principles.

Anyone can make a rule.

 

[JohnW2]

I believe the boilermen work on the principle that if you have a number of metal pipes, and a metal boiler, any one of which MIGHT be fixed to something with an electrical fault, and any of the others MIGHT be earthed, it is wise and safer to have them all bonded to each other. ... The boilermen are particularly likely to cut, disconnect and handle wet pipes that might otherwise have provided adventitious bonding.

Maybe, and under the circumstances you mention, it could offer some degree of protection top the 'boilerman'.

However, if the name of doing what you suggest, the 'boilerman' earths a pipe which "MIGHT be earthed" (but actually was not earthed) then, by so doing, he/she would have, at least theoretically, increased the risk to occupants of the property of electric shocks.

So ... swings and roundabouts, somewhat depending upon whom one most wants to 'protect'.

Kind Regards, John

 

[adaml]

Maybe, and under the circumstances you mention, it could offer some degree of protection top the 'boilerman'.

However, if the name of doing what you suggest, the 'boilerman' earths a pipe which "MIGHT be earthed" (but actually was not earthed) then, by so doing, he/she would have, at least theoretically, increased the risk to occupants of the property of electric shocks.

So ... swings and roundabouts, somewhat depending upon whom one most wants to 'protect'.

Kind Regards, John

Given we don't know what is happening under the floor boards. If I imagine a scenario where the currently unearthed CH loop pipework could be touching other copper that is earthed such as the cold feed to the bathroom, possibly an intermittant touching based for some reason like floor flexing when walking over pipes or thermal expansion making very close but not touching pipes actually touch each other. What do we do? Is it safe to assume the unearthed CH loop will never be touching an earthed pipe somewhere hidden in the floor voids?

 

[JohnW2]

Given we don't know what is happening under the floor boards. If I imagine a scenario where the currently unearthed CH loop pipework could be touching other copper that is earthed such as the cold feed to the bathroom, possibly an intermittant touching based for some reason like floor flexing when walking over pipes or thermal expansion making very close but not touching pipes actually touch each other. What do we do? Is it safe to assume the unearthed CH loop will never be touching an earthed pipe somewhere hidden in the floor voids?

I'm not quite sure what problem you are contemplating.

If the CH pipework ('unintentionally') happens to touch some earthed pipe, that would bee no different from the deliberate 'bonding' together of the pipes that we are discussing. If (extremely unlikely) the CH pipework was not already earthed, then unnecessarily connecting it to earth (whether deliberately or not) would theoretically increase the risk of electric shocks to occupants of the property.

Kind Regards, John

 

[ericmark]

In the main if you have RCD protection faults will trip the RCD before causing danger to the occupants. As said there is a balance, if you are standing on a floor at 230 volt to true ground and you touch some thing of true ground potential you will get a shock, so there is a risk assessment, and without RCD protection there is less risk if all is bonded, but with RCD protection this is not always the case.

The scenario given was dog knocks over a standard lamp in one room, which lands on the radiator, making that radiator live, and all other radiators connected by pipe work. But also if the radiator is bonded and you touch some thing live and the radiator current also flows. So there is risk both ways, and with RCD protection the dog scenario is likely to trip the RCD.

At one point we even earthed metal window frames, but all non class II items have an earth anyway, so should trip without needing to bond non electrical metalwork.

 

[JohnW2]

In the main if you have RCD protection faults will trip the RCD before causing danger to the occupants. As said there is a balance, if you are standing on a floor at 230 volt to true ground and you touch some thing of true ground potential you will get a shock, so there is a risk assessment, and without RCD protection there is less risk if all is bonded, but with RCD protection this is not always the case.

In the sense I was talking, that's not true.

You appear to be talking about the possible risk to someone touching two conductive parts (pipes or whatever) in which case, as you say, that risk will be minimised by bonding all such parts together.

On the other hand, I was referring to the risk of someone touching something 'live' (e.g. the casing of a faulty appliance, or even an 'exposed live conductor') and simultaneously touching a pipe/whatever. If that pipe is connected to earth, they will receive a serious electrical shock, but if the pipe/whatever is not earthed (i.e. electrically 'floating') they will suffer little, if any, shock. It therefore follows that, in such a scenario, to 'unnecessarily' connect an (otherwise 'floating') pipe/whatever to earth, will increase the risk of electric shock to occupants of the property.

The risk assessment therefore has to consider which is the more likely/common cause of electric shocks - touching two pipes simultaneously, or touching something else 'live' at the same time as touching a pipe/whatever. I don't know the answer, but suspect that the latter is probably more common.

Kind Regards, John

 

[ericmark]

The risk assessment therefore has to consider which is the more likely/common cause of electric shocks - touching two pipes simultaneously, or touching something else 'live' at the same time as touching a pipe/whatever. I don't know the answer, but suspect that the latter is probably more common.

Well put, that was what I was trying to say.

 

[JohnW2]

Well put, that was what I was trying to say.

Great. I've offered my guess as to which way that risk assessment is likely to go - what is your view.

Kind Regards, John