Just refurbishing abathroom and would appreciate some advice please.I am not an electrician but try to ensure a job is left safe as well as funtionaland looking pretty.The shower is on a 10 mm radial 45 amp MCB and RCD protected, the extractor and blower heater are in zone 3 and on the upstairs ring final RCD protected circuit and externally isolated.My problem is the lighting circuit is off the upstairs circuit and not RCD protected and no supplementry equipotential bonding is installed.I have checked that M.E.B. is inplace to services and connected to M.E.T. All piework is copper with metal compression or soldered jointing, all pipes at boiler are cross bonded and wastes in bathroom are plastic.I have noticed that a previos electrician has linked the cpcs of the shower pullcord and lihgting.My question is would it be acceptable to just get my electrician to bond the cpc of the lighting circuit to the water feeds to the sink bath and tiolet as there seems to be no other metal parts to introduce a potential.The customer does not want to put all the upstairs lighting on RCD.Also for my education, and I know on this forum I have seen mixed views about this, the 17th says that provided certain criteria are met if all circuits are RCD protected supplementry bonding in bathrooms can be ommitted but what is wrong with linking all cpcs of bathroom circuits and supplementry bonding (a sort of belt and bracers job) in case of RCD failure. your views would be very much appreciated.
Bathroom supplementary equipotential bonding
- Thread starter wesj
- Start date
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hi o/p you state that the shower is mcb and rcd protected, is the rcd the actual mains switch and rated at 30ma if so, then your mcbs are fed via a rcd and you should be ok, if not you will have to bond the bath.
A bath is not (usually) an ECP and does not (usually) need bonding. Provided all the services linked to the bath are bonded, there is no way the bath can introduce a potential in its own right.
Since not all your circuits in the bathroom are RCD protected, then supplementary bonding is needed. So as you say, bond all the incoming services to each-other and to the CPCs of all the circuits serving the bathroom.
Alternatively, having checked that the ECPs are effectively connected back to the MET already (with a low reading continuity tester) you could have an RCD FCU installed to protect just the bathroom lighting and no bonding then required.
I'd just fit the bonding as you can do that yourself.
Since not all your circuits in the bathroom are RCD protected, then supplementary bonding is needed. So as you say, bond all the incoming services to each-other and to the CPCs of all the circuits serving the bathroom.
Alternatively, having checked that the ECPs are effectively connected back to the MET already (with a low reading continuity tester) you could have an RCD FCU installed to protect just the bathroom lighting and no bonding then required.
I'd just fit the bonding as you can do that yourself.
If the bath is metal then I would personally bond it. I can see worse case scenario of spillage from the bath creating damp connections in the wall to a live conductor in the adjacent room bringing live potentials to the bath
Or the PME earth ( neutral ) rises due to a network fault and hence the bonded pipework raises the taps to a potential above ground but via the wet, maybe metal, waste pipe ( or damp walls or floors ) the bath has a connection to true earth.
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Yep, a metal waste pipe would also need to be main bonded too.
Re the bath there is an article on the IET website about earthing plastic pipes which covers the issue. Basically as long as any items which can cause the bathtub to introduce a potential are bonded then there is no need to bond the actual bathtub.
The flake advert wouldn't be the same with supplementary bonding
Re the bath there is an article on the IET website about earthing plastic pipes which covers the issue. Basically as long as any items which can cause the bathtub to introduce a potential are bonded then there is no need to bond the actual bathtub.
The flake advert wouldn't be the same with supplementary bonding
With spilt bath water in mind then maybe the live wires of the lamps in the room below need to be bonded.
Yes I accept that the risk of a bath tub being made live via damp from the ceiling rose in the room below is very small but for the sake of a length of wire and a few minutes work the risk is prepared for.
How much bath water do you spill
Me very little as I have almost always a shower and that room is tanked.
But I know people who have had one ceiling rose replaced at least twice due to water from "frolics" in the bath above the room. Probably would be more often if the last time it happened an RCB had not been added to the system to stop the water filled rose from sizzling away.
Thanks for your replys, so if I understand correctly although only the lighting circuit is none RCD protected I would need to join cpcs from all circuits and bond to pipes etc. Also from my original querie is it OK to fully RCD protect and also supplementry bond. Thanks again. Wes
Nothing wrong with using both RCDs and supplementary bonding.
I don't like the idea of the shower relying on the lighting circuit CPC for it's connection to the metal pipework, the other way around would be better imho, or use 4mm from shower to light and pick up the 4mm from the same point and continue it on to the pipes.
I don't like the idea of the shower relying on the lighting circuit CPC for it's connection to the metal pipework, the other way around would be better imho, or use 4mm from shower to light and pick up the 4mm from the same point and continue it on to the pipes.
thanks Spark 123 I will loop cpcs with 4mm and bond to earth clamp with same
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