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  1.  
    A colleague wants to add a light over his bathroom mirror with its own local switch next to the mirror. He is not impressed by the pull chord solution presented by his electrician. What are the options?

    David
    • CommentAuthorowlman
    • CommentTimeNov 18th 2015
     
    Try looking for "contactless light switches" . You can install them behind glass etc and I believe they are bathroom safe.
  2.  
    My parents have a couple of those (integrated into bathroom mirrors). You wave your hand in front of the sensor to turn it on and off.

    We are also having a PIR sensor fitted in our bathroom, but I can see this not being the best solution in all situations depending on how long you want the light on for etc....
    •  
      CommentAuthordjh
    • CommentTimeNov 18th 2015
     
    The contactless switches sound like a good idea, and another possibility would be a wireless switch with the receiver mounted next to the light fitting. It would reduce the amount of wiring needed.

    He can of course always just buy a conventional IP44 light with its own switch built-in and intended for use with a mirror. They're widely available.
    • CommentAuthorCWatters
    • CommentTimeNov 18th 2015
     
    You can install a switch but it has to have an IP rating suitable for that particular bathroom zone. Google bathroom zone.
    • CommentAuthorEd Davies
    • CommentTimeNov 18th 2015
     
    John Whitefield's _Electrician's Guide to the 17th Edition_ says no switches in the zones other than:

    - those incorporated in equipment installed there (appropriately IP rated) and

    - pull switches and SELV switches in zones 1 and 2.
    • CommentAuthorCWatters
    • CommentTimeNov 18th 2015
     
    I stand corrected.

    Would have to be more than 0.6m from the basin to be outside a zone.
  3.  
    Posted By: CWattersI stand corrected.

    Would have to be more than 0.6m from the basin to be outside a zone.

    Hmmm Looking at the zones it looks like 0.61 above the sink passes so this may be an option.
    • CommentAuthorEd Davies
    • CommentTimeNov 18th 2015
     
    This, from the IET who you'd think would know, seems to indicate that a sink doesn't necessarily have to have a zone round it (if it's far enough from the shower or bath):

    http://electrical.theiet.org/wiring-matters/53/section-701/index.cfm

    I've been confused in the past by the use of the word “basin” which actually should have been taken to mean shower basin but which I took to mean wash basin (i.e., sink).
    • CommentAuthorbarney
    • CommentTimeNov 19th 2015
     
    You need to think "wet and naked" when discussing the zonal concept of the special location (ie a room containing a bath or shower)

    A WHB in the bathroom is no more of a risk than the kitchen sink - in fact it is probably less risk in terms of electrical safety

    Once you are beyond a dimension of 600mm measured from the vertical edge of the bath or shower tray, then (assuming reasonable ventilation) a "normal" light switch will be fine

    Regards

    Barney
    • CommentAuthorrhamdu
    • CommentTimeNov 19th 2015
     
    Last two posts are correct. I was looking at this very point in the latest wiring regulations, on Monday.

    Unfortunately manufacturers often issue incorrect diagrams with their products. So the myth continues.
    •  
      CommentAuthordjh
    • CommentTimeNov 20th 2015
     
    Posted By: barneyOnce you are beyond a dimension of 600mm measured from the vertical edge of the bath or shower tray, then (assuming reasonable ventilation) a "normal" light switch will be fine

    I think there has to be a shower enclosure around the shower tray, and in wetrooms the zone extends further (depending on the reach of the shower hose). Or have I been I misinformend?
    • CommentAuthorbarney
    • CommentTimeNov 20th 2015
     
    No - my description was a brief summary of the zonal concept and the wet and naked bit tells you why - if you want the detail, read BS 7671 Section 701

    If it is a wet room with no defined shower basin, then substitute 1200mm from the shower head for the 600mm dimension

    Then we can get into the semantics of the "all circuits of the special location" debate

    Regards

    Barney
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2015
     
    There's a separate section of the wiring regs (sorry, don't have a reference) which says that equipment needs to be suitable for the intended application. Duh! But who says what's suitable? I had a look through some switch datasheets on a supplier's web site yesterday. Not surprisingly, only a few manufacturers have them - mostly those with a wide range of more-complicated devices like dimmers and shaver sockets in the same range. None had any statement either way on the suitability of their switches for bathrooms.

    The best that could be said is that ranges including shaver sockets, which clearly are likely to be installed in bathrooms, didn't make any distinction between devices which are and are not suitable. The only thing I saw was an exemption on the guarantee for some from use in “humid” environments. You'd have, I think, a hard time proving that your bathroom wasn't humid even assuming, as Barney puts it, reasonable ventilation.

    In other words, I think a straightforward off-the-shelf light switch is legal and safe in a bathroom in a sensible place outside the zones but in practice you'd have a hard time putting a paper trail together to prove it to a stroppy electrical inspector or BCO who just doesn't like the idea out of habit.
    • CommentAuthorbarney
    • CommentTimeNov 20th 2015
     
    OK - bathrooms (amongst others) are defined as "special locations" due to the increased shock risk (my wet and naked comment)

    All special locations fall under Section 7 of BS 7671 - locations containing a bath or shower is covered in Section 701

    Section 701 provides for specific requirements and/or modifies the general requirements of BS 7671

    WRT to switches etc, once beyond that notional 600mm (or 1200mm) line then they simply need to have a recognisable ingress protection rating - in this case IPX4

    The first number (in this case omitted and replaced by X) defines protection against the ingress of objects (including fingers)

    The second numeral defines the level of protection from water - 4 is representative of Water splashing against the enclosure from any direction shall have no harmful effect.

    So, it's a matter for the designer - in the vast majority of cases a normal wall mounted plate switch will achieve the above criteria

    More generally, for all electrical installations covered by BS 7671, Chapter 52 provides "general rules" relating to "selection and Erection of Wiring Systems" and Section 522.3 requires a wiring system to be selected and erected with cognisance of the presence of water or high humidity

    That should make it clear as mud

    Regards

    Barney
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2015 edited
     
    Posted By: barney: “WRT to switches etc, once beyond that notional 600mm (or 1200mm) line then they simply need to have a recognisable ingress protection rating - in this case IPX4”

    My reference says IPX4 for zones 1 and 2 (or IPX5 in some circumstances - if jet washing is likely) but nothing about outside the zones but it could well just be missing it out so you're likely right but it'd be nice to know for sure.

    Still, finding a switch which is IPX4 might be tricky. Take https://www.tlc-direct.co.uk/Technical/DataSheets/MK/PlateSwitches.pdf as an example. They're specified as IP4X (blue “Technical Specification” box on left side of page 2) so no specified protection from water ingress, just from things bigger than 1 mm across poking in holes.
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2015
     
  4.  
    Thanks for the feedback. Some of the guys at work suggested using PIR sensors and one suggested capacitive touch sensors:

    http://www.taptilecontrols.com/
    http://www.sensor.co.uk/switches/bathroom_switch/

    He wanted something more flexible, so designed his own capacitive touch sensors behind the tiles, using an arduino, copper tape, etc. A very neat solution, but you have to wonder how much it consumes when left on 24x7.

    David
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