Bathroom wiring

Discussion in 'Electricians' Talk' started by legit, Nov 16, 2004.

  1. legit

    legit New Member

    Hopefully I can get this post in before screwfix goes down again!

    My wife would like a new bathroom and we've bought one of those heating elements to stick in the new towel radiator - and what I'm not sure about is the best way to wire it. I understand the conventional way is to but a flex outlet plate for the flex and then to run 2.5mm cable up to a switchless FCU out of touching distance of the bath, I believe this is 600mm.

    However because we like to keep the electrical boxes to a minimum, I'm toying with the idea of putting an ordinary switch outside the bathroom with no flex outlet plate. But can I do this, ie stick flex through a plasterboard partition through to the other side?

    Secondly, while I'm putting one type of switch outside the bathroom, I thought I'd take the opportunity to get rid of the pull cord lightswitch and put an ordinary one outside alongside. So can I get some sort of combined fixture with two switches on to operate both??

    When finished, my work will be checked over by a fully qualified electrician.

    Many thanks for your comments.
  2. Jonny

    Jonny New Member

    It's not ideal - the flex outlet is your way of being able to replace the fitting when the heater fails in the future. Could run the flex vertically down, under the floorboards to a junction box there?

    Only use a switchless FCU if there is a means of controlling the heater built in to it - otherwise you will need this to control it.

    A normal switch is not good, as there is no fusing down, if you are wiring into the ring main. If fusing is provided elsewhere (dedicated circuit at the CU / FCU in a cupboard elsewhere (but still accessible), then you could use a double pole 20A switch for isolation(with or without neon) - these usually look similar to a standard plateswitch.

    Given the above regarding a 20A DP switch, and that 2gang DP switches aren't available (except labelled for immersion heaters), the only way to fit both switches into a single box would be to use a grid system - MK GridPlus would allow you to buy a 20A DP (MK K4896 BSS W) and a 10A single pole sw (MK K4881 BSS W). The 20A DP module is available with inscriptions, such as HEATER, or in red, one of which would be useful to indicate which switch is which.
  3. legit

    legit New Member

    Hmm, I suppose the junction box under the floorboards is my only other option. Trouble is, to get at it if I need to make repairs would involve taking up the vinyl then the hardboard before I would even get to the floorboards. On balance it looks as if I will have to use the flex outlet plate, which like you say, makes it easier to replace the heater.

    I have tallked my wife into getting rid of the pullcords and putting switches on the outside, so that's a bonus. It's just a shame the manufacturers don't do combined fixtures, because looking round my home there are lots of instances where I could potentially slim down on my face plates.

    I've swapped my switchless fuse spur with one with a switch on and a neon light, and plan to spur off of the nearest socket.

    Thanks for the advice.
  4. Jonny

    Jonny New Member

    Don't forget to fuse this spur, so add a FCU (unswitched?) next to the socket you're spurring off.

    If the heater is on lift-off brackets, could the flex plate be positioned behind it, so you could lift off the heater to get to it?

    Or a removable section of skirting, with a JB behind it?

    You can make pretty much any combination of switches and some sockets using MK Grid Plus - very flexible system. Either switches with built-in neons, or a seperate neon module can be incorporated.
  5. legit

    legit New Member

    Damn, I was all set to go. Do I really need a third box next to the socket I'm spurring off? The reason I sound doubtful is that in my garage I spurred an FCU off of a socket and into this FCU I wired the electric unit for the garage door. The electrician checked this over.

    Maybe its terminology - electricians in Northampton for some reason speak two dialects: one third speak of FCUs and the other two thirds speak of switched fused spurs, and honest to god have never heard of FCUs. Even the ones from the yellow pages. My readers digest book also refers to FCUs.

    Just to be sure I'm on the right track here is my plan in the best terminology I know. I plan to have an FCU (with neon light) spurred off of the plug socket outside my bathroom door followed by a flex outlet plate inside the bathroom connected by flex to the heating element inside the towel radiator. All cable will be 2.5mm. Am I on the money or do I really need a third fixture??

  6. bighairybloke

    bighairybloke New Member

    FCU= Fused Connection Unit. a switched fused spur is an FCU with a switch on it.

    If you're fitting one of them, you wouldn't need the extra one by the socket.

    Don't forget to check that the socket isn't already on a spur itself, you must connect into the actual ring.
  7. legit

    legit New Member

    I'm feeling a little more wizened now. Cheers for your help guys! Right, I'm off to B&Q, trained up in a little corner of sparkie lingo.
  8. Jonny

    Jonny New Member

    Yeah thats fine, sorry I thought u meant use an unfused DP switch outside the bathroom, not FCU. Make sure the ring you are spurring from is RCD protected, otherwise use an FCU with built-in RCD.
  9. ban-all-sheds

    ban-all-sheds New Member

    You could put a switched FCU somewhere unobtrusive (e.g. next to a socket) - that would give you your DP isolation.

    Once that's done, ignore all the twaddle about 20A switches - even cheapo light switches are rated at 6A, and decent ones like MK are rated at 10A. Your towel rail element won't exceed those.

    Whatever you do though, the biggest problem will be that you'll end up with two circuits in the same box - ring main and lighting, so you must clearly label it; the danger is that some future occupant, wanting to, say, replace the switch, might turn off only the lighting circuit, and dive in unaware until he finds out the hard way that there are still live wires in there....
  10. Jonny

    Jonny New Member

    Agree with you about this not being best practice BAS, but do you know of a specific reg highlighting this? I'm sure there is one but have not yet been able to find it.
  11. ban-all-sheds

    ban-all-sheds New Member

    Group 514-11, I believe....
  12. Jonny

    Jonny New Member

    Isolation from a single device IS possible in theory - by the main switch! It'd be useful if there was a grid system which provided the necessary protection for two circuits, so the frontplate could be removed, but protection against indirect contact was still afforded, and there would be a seperate case over each switch supplied by different circuits...
  13. legit

    legit New Member

    Screwfix is working again!

    Ok job done, I've kept it simple: Just an FCU and lightswitch next to each other outside the bathroom door. BAS, I see what you mean about having two circuits feeding into to same box, could be very confusing to future occupents!

    The hall looks a little worse electrics-wise, but the bathroom is now a haven with no light pull (that always used to catch in the door), no fcu and no pull cord switch for the fcu. Basically just a flex outlet plate more or less out of view. Another advantage is that as you go upstairs to bed you can instantly see whether or not somebody has left the towel heater on.

    Biggest bi*ch of a job was getting at the light switch wiring under the loft boards. Not only is our loft a complete Aladdins cave, but the boards are tongue and groove and not coming out any time soon. Basically a lot of bug*ering about drilling pilot holes to get at junction boxes.

    Anyway cheers guys for steering me through this one, the wife is very happy and as you all know, that's the number one concern!

    Fantastic website.
  14. ban-all-sheds

    ban-all-sheds New Member

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