Bathroom notifiability

[kentishman]

Is work done in a bathroom, but outside the zones, notifiable? I'm thinking of installing some under-cabinet ELV 12V led lighting in mine. The power supply will sit in the loft and just the 12V cable will drop into the bathroom. The cabinets are 1.2 metre horizontally from the bath.
Thanks for any replies.

 

[EFLImpudence]

Is work done in a bathroom, but outside the zones, notifiable?

No.

 

[kentishman]

I like it, quick and to the point!
Thank you.

 

[JohnW2]

I like it, quick and to the point!

In addition to the matter of (non) notifiability, there is obviously also the issue of compliance with regulations.

Current regulations require that any circuit supplying a bathroom (even if outside of Zones) must be RCD protected, and I don't think it makes an exception when the circuit is supplying SELV items. Any new buried cables would also almost certainly be required to be RCD protected, and to follow acceptable routes (in 'safe zones'). Is the circuit concerned already RCD protected?

Kind Regards, John

 

[kentishman]

Good point John, yes the circuit it will be connected to has RCD protection.

 

[ericmark]

How can any SELV be RCD protected? I have never seen a RCD that will work with 12 volt, and even at 230 volt with an IT supply a RCD is not really going to work.

The supply to the isolation transformer will likely need RCD protection if the cables are not other wise protected, and where the transformer is hidden under the bath then the bath panels will need a tool to remove them, or deliberate action.

 

[JohnW2]

How can any SELV be RCD protected? I have never seen a RCD that will work with 12 volt, and even at 230 volt with an IT supply a RCD is not really going to work.

For a start, an RCD without electronics would know nothing about voltage, and so would work as well with a L-N PD of 1V as with 230V - but the ones with electronics (most/all of them these days, it seems) will presumably have a minimum L-N voltage at which they will work. ... not that there is any point/need in RCD protecting an ELV supply.

However, that's not the point. Current regulations require any (230V) circuit "serving a bathroom" to be RCD protected and, as I said, that would seem to remain true even if it only supplied loads via an SELV transformer/supply which is outside of the bathroom. Whilst that, per se, makes no real sense, I imagine that the requirement probably exists because of the possibility of the circuit being used for non-SELV loads in the future.

The regulation even requires RCD protection of any circuits which merely 'pass through' Zones 1 or 2 of a bathroom, but do not 'serve' the bathroom, which makes even less sense.

Kind Regards, John

 

[ban-all-sheds]

For a start, an RCD without electronics would know nothing about voltage, and so would work as well with a L-N PD of 1V as with 230V - but the ones with electronics (most/all of them these days, it seems) will presumably have a minimum L-N voltage at which they will work. ... not that there is any point/need in RCD protecting an ELV supply.

Even if it would work at an EKV, where would a current imbalance come from with a SELV supply?

 

[JohnW2]

Even if it would work at an EKV, where would a current imbalance come from with a SELV supply?

That was really what I meant when I wrote "not that there is any point/need in RCD protecting an ELV supply."

In any event, as I wrote to eric, that is not the point. We were talking about regulations, and the regulation relates to 'circuits serving a bathroom' - which I presume means LV (not ELV) circuits, even if the 'serve' the bathroom by feeding SELV power supplies.

Kind Regards, John.

 

[ericmark]

The regulations in 2008 not sure if corrected stated how cables buried in walls had to etc etc without any reference to the voltage or earth requirements of the system. However it does state the three types of extra low voltage.

One must have an earth, one it is optional and one must not have an earth so it is plain with separated you will not use a RCD, this does not matter if bathroom or just the door bell, the selv part of any system is not protected by a RCD, the transformer may be protected but after the transformer nothing.

There is a point of course with reduced low voltage, however again any RCD protection has to be after the transformer, I have yet to see a yellow brick with a RCD built in, I have seen some in line 110 volt RCD's but they seem rare, and that is 55 volt to earth with a system which should not be earthed at 12 volt it seems daft to even try and use RCD protection.

 

[JohnW2]

The regulations in 2008 not sure if corrected stated how cables buried in walls had to etc etc without any reference to the voltage or earth requirements of the system. However it does state the three types of extra low voltage.

I couldn't be sure about this particular case, but it seems that a fairly common failing of the regs is for a regulation not to distinguish between ELV and 'not-ELV LV' circuits, even when the regulation concerned makes little, if any, sense in relation to ELV.

However, as I keep saying, the reg we're talking about requires RCD protection of any (presumably '230V') circuit 'serving a bathroom' (or even just 'passing through' Zone 1 and/or Zone 2 without 'serving' the bathroom at all), seemingly regardless of what in the bathroom is 'served' by that circuit, and how (i.e. 'directly or via an ELV supply).

Kind Regards, John

 

[John D v2.0]

I'd say the circuit ends at the elv transformer, then that's the only thing served. The things in the bathroom are served by the elv circuit. Just common sense really due to the isolation.

 

[JohnW2]

For a start, an RCD without electronics would know nothing about voltage, and so would work as well with a L-N PD of 1V as with 230V - but the ones with electronics (most/all of them these days, it seems) will presumably have a minimum L-N voltage at which they will work. ...

I'm just 'done the (preliminary) experiment' and, even with electronics, they are even less concerned about voltage than I suspected ...

... a bog-standard (brand new) Wylex 80A 30mA RCD trips with ~30mA imbalance all the way down to a supply voltage of 6V. I haven't yet tried lower voltages than that, nor have I looked at the actual trip thresholds and (if my meter will do it) trip times at low voltages - but I will look at those things in due course.

Kind Regards, John

 

[JohnW2]

I'd say the circuit ends at the elv transformer, then that's the only thing served. The things in the bathroom are served by the elv circuit. Just common sense really due to the isolation.

Common sense, yes but don't forget that the same regulation requires RCD protection of a circuit which 'serves' nothing in the bathroom if it happens to 'pass through' Zones 1 and/or 2, so I'm not convinced one can rely too much on the common sense basis of the reg!

However, having just looked at it properly, the reg actually does relate specifically to "low voltage circuits" - which in BS 7671-speak (but apparently not IEC-speak) excludes 'ELV', so maybe you're right.

Having said that, this could get a little silly. If we're going to say that the 230V supply is not serving the bathroom because it's only serving an ELV transformer above the ceiling (I imagine that it would be considered to be 'serving the bathroom' if the transformer were actually in the room?), then what about a recessed downlight, all the electrical parts of which may also be above the ceiling?

In any event, if there were any non-ELV lights (or a shaver socket, or anything else) in the room on the circuit, then the reg would require RCD protection for that reason, even if there were also ELV items.

Kind Regards, John

 

[ban-all-sheds]

How can any SELV be RCD protected?

For a start, an RCD without electronics would know nothing about voltage, and so would work as well with a L-N PD of 1V as with 230V

No it would not.