Another mains power in bathroom question

Simply put, I want to put two mains feeds into my bathroom. One for a shaver socket and another that will power an illuminated mirror.
I intend to spur off the bathroom extractor fan wiring for my shaver socket and spur off my switched bathroom light wiring for my mirror. I hope that this sounds correct. The idea being the mirror will illumunate when the main lights are on. The cabling will be plastered over.
My first question is, does the cable need to be inside some sort of metal conduit of it runs directly down the wall from the loft area? Or can it be plastered over? This applies to both fixtures.
My second queston is, do I need any sort of RCD proection for both fittings? Im not sure on the IP rating of the mirror but both that and the shaver socket are in zone 2. Had a quick look on the TLC website and have seen a few RCD devices that I think would fit the purpose.
Can anyone advise on exactly what I need to do to make this a safe installation?
Thanks as always,
CM.
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snipped-for-privacy@btinternet.com (Charles Middleton) wrote in message news

Go carefully on this one! Hopefully one of the real experts on uk.d-i-y will come in, but pending that some comments:

That is usually fed from the lighting circuit
for my shaver

which means they'll both be on the same circuit from your consumer unit? (You'll need to check this).
The idea being the mirror will

regret I'm unfamiliar with these. Are they effectively wall lights? ISTM the main Qs here are:
? is the mirror unit fixed? - if not suspect you may fall foul of some IEE reg re movable/portable kit in a bathroom.
?What sort of connection fitting is to be used to connect to the mains wiring?
?is the mirror light rated for bathroom use (check the manuf spec & look for the IP rating)
?any external metal parts? - if so you'll need to add supplementary bonding
Provided you can sort out above points satisfactorily you may be in with a chance but FWIW my guess is you may need to run this mirror light through an isolating transformer.
If this is like a normal light fitting you'll be ok running 1mm or 1.5mm twin & earth to it. Some people just hold the T&E on to the wall under the plaster with a tower clip at the point where it comes out of the wall & the connect the T&E directly to the back of the light fitting & screw the whole lot to the wall. Others use a standard backing box. Another (neater IMHO) alternative is to bring the mains out through one of those narrow backing boxes used for kitchen light switches.
As for the shaver you should check the manuf spec or the box. Normally shaver sockets in a bathroom must be run via an isolating transformer & complete units often with integral lights are sold to this spec.
The cabling will be plastered

You can tack the T&E to the wall with tower clips, or hold it in place by covering it with metal or plastic capping before plastering. Provided the cable makes a straight vertical or horizontal run to the take off point you're ok & don't need to earth the capping. For other runs check back or see IEE web site which has pointers to diagrams of permitted cable routing.
BTW capping is NOT conduit

SFAIUI you don't need an RCD for an isolating transformer type shaver socket, & suspect the same might be correct for a properly specced light mirror- but hopefully more experienced heads on this group will come in.

would respectfully suggest you do nothing until someone else on this group comments.
HTH
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Thanks for the reply ....

Yes, checked the wiring and it is fed of the lighting circuit.

my mirror. I

Yes, they will both me running off the same circuit which is for the upstairs lighting.

When you say fixed what do you mean? It is screwed into the wall.

This is my main question and looking at the mirror in the bathroom showroom over the weekend it appears to be just a block connector but I may have that wrong ...

... however according to the sales person it is suitable for bathrooms and has an IP rating. The sales person justified this by telling me that the lamps are low voltage and the frame of the mirror houses a transformer. I supose it may be possilble to relocate the transformer to the loft as. However, it stands to reason that the mains wirining will terminate inside or around the transformer.

The frame that the mirror sits upon which screws to the wall is painted metal. I presume that that will require bonding.

What is the purpose of an isolating transformer. Is this like an RCD? I presume that this would fit in line on the mains cable.

I intend to simply bring the cable out through the wall as it will be well hidden.

This is an MK unit - the instructs specify it must be wired to either an RCD or an MCB, in my case the lighting circuit is not RCD protected. The shaver socket is a plastic unit but with a metal back box behind it. I intend to earth the T&E to the back box.

Im not sure if the unit is an isolating transformer type. It contains a transformer but is this jus to provide the 110v?

I think your right, either that or I'll get an electrician to advise.
Thanks for your help,
CM.
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It needs the *correct* IP rating for the place it is to be used, not just "an IP rating".
--
Chris Green

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<snip>
yes that's what I meant ie not something you can pick up & wave about.

sounds standard. you just connect the wires coming out of the wall to this block. However my recommendation is to bring the cable out through an inset small narrow type metal backing box in the wall. For one thing it means the cable won't work the plaster loose & it helps keep the cable off the possibly hot light fitting, safeguarding the insulation.

that's a start but what does it say on the box. You'll also need to check (as another poster noted) that the Ip code covers what you want to do. I have a table of IP nos somewhere but cannot put my hands on it. However it must have come off the web, so googling might find the list for you.
The sales person justified this by telling me that the

no, just keep the unit as it is as long as the 240v end is not accessible (which prsumably will be the case once it is screwed to the wall).

that's Ok & is how shaver outlets are made & installed.

there's some exemptions for small metal parts: how large an area is the exposed metal? Does the box have a manuf tel no? If so try ringing & ask for tech help. IMHO the metal case should at least be connected to the CPC (ie earth) lead in the T&E cable. But another Q for an expert...

NO defintely not. An RCD detects when the current in the live red L lead doesn't match the current in the neutral blue N lead. the assumption is that there must be a leakage to earth - ie a fault & it chops the circuit dead quick.
The voltage output of an isolating transformer just 'floats'. With the standard public supply Neutral is tied to earth so Live is at 240v & you normally get a shock if you touch it because normally your body is at roughly earth potential. However with the isolating transformer neither output end is tied. So as soon as you touch one end, that end becomes tied to earth & there's no shock. (NB You will get a shock if you touch both ends at the same time) In your case if the isolating transformer is also reducing the voltage to a 'low' (?safe = less than 20v or so) volts you're further protected if you did touch both ends. FWIW it sounds to me as if this mirror light will be OK, but be sure you understand what you;re doing.
BTW it is not normal to fit an RCD to a lighting circuit (unless you have a TT supply or some other requiremnent). It is usually reckoned to be safer to have lights on even if a fault occurs especially as you're unlikely to be touching the light circuit when a fault occurs.
<snip>

see above

I suspect this unit is unsuitable for bathrooms. beware. you need a transfomer unit just like you have described for the mirror light. Look around for other makes/models. try looking on the Mk website for the whole range. You CAn buy suitable units often with built in lights to go over a mirror.

am now not sure what you have.
look for more info before proceeding: Try browsing the options in a large B&Q warehouse. HTH
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This all seems to be becoming rather convoluted here. The IP rating for bathroom use normally (assuming it's not in an area like a shower etc. or very near the bath) is very 'low'. AFAICS basically the lamp has to be protected form being splashed and the switch (if fitted) must be safe to use - which normally means a pull switch for use with wet hands.
Anyway, as important in all this would be consideration of what zone in the bathroom the light was going - though in reality, it will probably be zone 3 or maybe zone 2 (0.6m of the edge of a bath or shower)
Evidently this is a light designed to be used in a bathroom, the lamp is enclosed by some sort of shade or diffuser? it has a pull switch (if switched?)? it is being mounted on the wall, probably above or near a hand basin? If so then go ahead it sounds fine.

<snip>
Why, sounds standard enough to me.

This sounds a standard bathroom wall socket type shaver outlet. The transformer provides both the 110V output and also acts to isolate the 240V output. You can get outlets with just a 240V output but these are not suitable for bathroom use as they don't have the transformer.

Says 'RCD or MCB' - I think this is because of the necessary disconnection times which would not be met if fed via fuse in the consumer unit, or maybe MK just playing safe - if the supply has an MCB, then all is fine.

Probably an MK701 Shaver supply Unit:
<http://www.mkelectric.co.uk/products/item.asp?itemidB06&rangeid 30>
safe for bathroom use.
--
Chris French, Leeds

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Thanks all for the advice ....

The lamp is protected from being splashed plus is low voltage. The whole thing is surrounded by a metal frame that screws to the wall and then the glass mirror mounts on top of the frame.

It will be situated in zone 2 - albeit the shower that it will be next to will be an enclosed shower so minimal risk of getting splashed from that.

Not sure if it has a pull switch, it will be switched primarily with the main bathroom light switch. It is being mounted above a wash basin so my only concern was moisture getting behind the metal frame and condensation building up on any exposed contacts.

Supply does have an MCB.

That is the exact unit. So, Live and Neutral to the terminals and earth the back box. Should be fine!
CM.
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