Electrical earth question.
Discussion
Morning everyone.
I hope i might be able to tap in to some info from the group.
A friend of ours has been in her house for just over twelve months and she has a newish oil boiler in the utility area of her house.
Over the last week she had it serviced and the oil guy said that the earth wire wasnt connected to the oil feed pipe but might not need it.
So the question is, does it need connecting to the pipe? I have offered to do it and it looks like i need one of these..
https://www.screwfix.com/p/greenbrook-ec14-interna...
But the worry is these clamps might be too big as after digging round the pipe is 10mm.
Is there a type that fits to small pipe?
I hope i might be able to tap in to some info from the group.
A friend of ours has been in her house for just over twelve months and she has a newish oil boiler in the utility area of her house.
Over the last week she had it serviced and the oil guy said that the earth wire wasnt connected to the oil feed pipe but might not need it.
So the question is, does it need connecting to the pipe? I have offered to do it and it looks like i need one of these..
https://www.screwfix.com/p/greenbrook-ec14-interna...
But the worry is these clamps might be too big as after digging round the pipe is 10mm.
Is there a type that fits to small pipe?
“It might need to be”? Seems like even the professional doesn’t know.
I’d go a different route, check building control to see if it was recorded/signed off when it was installed, if it was then I would trust it’s been done ok, and you have reasonable grounds to believe that.
The bigger worry is whether the house plumbing is earthed but that wasn’t flagged.
I’d go a different route, check building control to see if it was recorded/signed off when it was installed, if it was then I would trust it’s been done ok, and you have reasonable grounds to believe that.
The bigger worry is whether the house plumbing is earthed but that wasn’t flagged.
Sheepshanks said:
Maybe the oil feed pipe has been replaced with plastic?
If the pipe is above ground it will either be metal or plastic shrouded copper pipe, we have plastic shrouded and just inside the wall the plastic has been put back for the earth clamp to be fitted. Plastic pipe isn't up to regs.Easy enough to find out what the BS7671 requirements are for equipotential bonding of extraneous-conductive-parts.
This may enlighten https://electrical.theiet.org/bs-7671-18th-edition...
This may enlighten https://electrical.theiet.org/bs-7671-18th-edition...
Mostly this is about making sure a fault can't reach you (in this case from outside) on anything conductive without there being an earth other than you.
Fuel oil maybe doesn't count as conductive (??) but if it was a water supply, even if the supply pipe is plastic the contents are quite capable of making you regret not having bonding somewhere if there's an external fault and you can touch something conductive connected to it.
I've regretted touching water that had enough external volts on it that the local earth couldn't pull it down far enough down to ground to not notice the tingle.
Fuel oil maybe doesn't count as conductive (??) but if it was a water supply, even if the supply pipe is plastic the contents are quite capable of making you regret not having bonding somewhere if there's an external fault and you can touch something conductive connected to it.
I've regretted touching water that had enough external volts on it that the local earth couldn't pull it down far enough down to ground to not notice the tingle.
I think technically it only needs to be earthed if the incoming pipe is conductive; but it's generally good practice to earth-bond any large piece of conductive material in the house, especially one which runs anywhere near mains voltage electrical cables.
Strictly, as far as I know, even water pipes only need to be earth bonded if the rising main is metallic. It's generally a good idea to earth them anyway, though! Ideally the earth bond should be connected directly to the meter where the earth/neutral line comes into the properly rather than to a random earth somewhere on one of internal circuits.
ETA: I suppose bonding it to the boiler's own incoming earth will at least cause a trip if the boiler's mains supply somehow gets shorted to the pipe, which is better than nothing, since pretty much by definition that earth should be fat enough to carry the current the incoming mains feed can supply for long enough for the RCBO to trip. I suspect in practice the metal fittings will mean that the incoming oil pipe is electrically connected to the boiler's case anyway.
Strictly, as far as I know, even water pipes only need to be earth bonded if the rising main is metallic. It's generally a good idea to earth them anyway, though! Ideally the earth bond should be connected directly to the meter where the earth/neutral line comes into the properly rather than to a random earth somewhere on one of internal circuits.
ETA: I suppose bonding it to the boiler's own incoming earth will at least cause a trip if the boiler's mains supply somehow gets shorted to the pipe, which is better than nothing, since pretty much by definition that earth should be fat enough to carry the current the incoming mains feed can supply for long enough for the RCBO to trip. I suspect in practice the metal fittings will mean that the incoming oil pipe is electrically connected to the boiler's case anyway.
Edited by kambites on Monday 19th October 14:54
Gone fishing said:
It might need to be ? Seems like even the professional doesn t know.
This is fairly standard practice from plumbers/gas/oil techs.... It's simply something to flag up to the customer for an electrician to check if bonding isnt visible within 600mm or tee of a gas meter or at the closest practical point after entry to the building on any other service. Aside from that IET 544.1.2 is well out of scope for anyone but an electrician.No point just connecting up an earth clamp and assuming the other end wasnt also left unfinished.
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