And what benefit is there in adding/leaving the EP connected?
Equipotential bonding required for new boiler?
- Thread starter 3phemeral
- Start date
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Probably because the ';training' seems often to leave a lot to be desired (and/or the individual is not really capable of being 'trained').
Here is some bonding to a towel radiator found earlier today:
Here is that same bonding and some others after I cut it all out:
Whoever installed this mess was evidently unaware of what bonding was for.
The radiator is connected via plastic pipes.
The rest came from some bathroom basins where someone had connected to the short lengths of copper pipe below the taps. Hot and cold pipes to the bathrooms are plastic.
Without bonding, the radiator and taps are just metal objects in the bathroom. No problem there.
With bonding they become big lumps of earthed metalwork connected to the electrical installation which is much worse.
Here is that same bonding and some others after I cut it all out:
Whoever installed this mess was evidently unaware of what bonding was for.
The radiator is connected via plastic pipes.
The rest came from some bathroom basins where someone had connected to the short lengths of copper pipe below the taps. Hot and cold pipes to the bathrooms are plastic.
Without bonding, the radiator and taps are just metal objects in the bathroom. No problem there.
With bonding they become big lumps of earthed metalwork connected to the electrical installation which is much worse.
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Is it worse, as in dangerous, if the EP bonding overall is properly installed?
I am not sure there is an answer to that question because the words do not actually make sense.
It is worse, as in dangerous, if unearthed metal parts are earthed by unnecessary bonding, so how can the bonding be properly installed overall?
It can be (potentially dangerous) in situations such as flameport described, when a large and touchable metal object is connected to earth (via 'bonding') when it would not be so connected (e.g. because it was a radiator supplied by plastic pipes) in the absence of that bonding.
In that situation, if someone somehow touches something electrically 'live', they will not get a significant shock
If the radiator were supplied by metal pipes, then it is extremely probable that it would already be connected to earth. In that situation, although totally unnecessary,'bonding' it would do no harm.[/S]
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Should there be another 'not' or no 'nots'?
There are two schools of thought on that....
If the metalwork is well isolated from earth, with absolutely no chance of becoming live, then it is better that it is not bonded. Where there is any chance of it becoming live, due to fault, or potential error - then it is safer if it is bonded.
That is the definition of an exposed-conductive-part and therefore it should be earthed; whether it needs bonding as well is a separate matter.
Well spotted. There's not problem with the "nots", but my fingers typed "if" when they had been told to type "unless".
Now corrected!
There are, as bernard often reminds us - but it depends upon one's judgement/assessment as to which of two scenarios is the more likely to occur...
Yep, if I understand correctly, that's what bernard feels about metal bath. He feels it more likely that something will somehow make a 'floating' bath 'live' than that someone would touch something live whilst also touching an earthed metal bath. By no means everyone would agree with that.
I see it as an all, or nothing scenario... You either make sure as much touchable metalwork is bonded, or you make absolutely sure none of it is bonded, and take extra precautions to ensure nothing can accidentally become live, ever. In my home, every bit of touchable metal, which has any chance of becoming live, is carefully bonded. My bath, bath taps, shower, wash-basin, radiator, are all bonded to each other, and to the main earth. My boiler, in the kitchen has the flow, and return pipes bonded, the sink taps, and the radiator. The utility room, the same, except it includes a metal sink, so that is bonded. In other rooms, the radiators, the only fixed metalwork, are also bonded.
I thought the whole point of EP was to equalise the potential in such situations, so that there is no or low shock.
It is. If there are two or more items which could have different potentials, they are bonded together to keep them at the same potential.
Typically it's items which introduce earth potential from outside (such as metal pipes) and other metal parts connected to the electrical installation.
However if something has no potential (not connected to anything else) then there is absolutely no point in bonding it.
The radiator example with plastic pipes cannot have any potential - it's just a metal object on the wall. Same applies to a metal door handle or a drawer of metal cutlery.
Bonding is not based on whether items are conductive - it's whether they are conductive AND can introduce a potential into the location.
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