Dimmer swich in bathroom

[r.p.mcmurphy]

im fitting halogen spots in my bathroom...id like to be able to dim them....is there any dimmers specifically for this application or can i just use normal ones?

Steve

[Andy Hall]

There are pull cord ones.....

[BigWallop]

What type of switch is on the circuit already, and where is it in relation to the bathroom?

If the switch is already outside the bathroom door, then any normal dimmer switch and proper dimmable low voltage transformer will do the job. If the switch is inside the room on a pull cord, then you can get dimmer pull cords for this purpose. But you need to have a proper dimmable low voltage transformer on the lights to do this with any type of dimmer switch.

[r.p.mcmurphy]

I am moving the bath room into the bedroom next door as its bigger and so has a normal light switch on the wall. the halogens are 240 volt.

Steve

[Andy Hall]

If it becomes a bathroom, you have to follow bathroom wiring accessory rules.

The rules for the bathroom electrical environment are summarised in

can have a wall switch as long as it is in zone 3 or beyond as long as it meets the IP rating required - normal ones don't.

[BigWallop]

If you're changing use of the room to a wet area such as a bathroom, then you'll also need to change the switching to outside the room door, or have pull cord switching fitted within the room itself.

If you're using mains voltage light fittings then you're OK for a dimmer of the correct capacity load rating for the amount of lighting you're going to use. But again, the switching must, not just should, be either outside the wet area or within it but with the use of pull cord mechanisms.

[Andy Hall]

Pull cords are always allowed.

Wall switch use is determined by the zone definition.(3 or outside) and the IP rating of the switch.

[ARWadsworth]

Have the neighbours not objected to this ;-)

Sorry. I could not help the poor joke.

But if you follow Andy's link to NIC bathroom zones then you will be OK.

Adam

[John Rumm]

I have noted there are some subtle areas of inconsistancy with regard to the advice that seems to be offered in various documents on what is and is not permitted in various zones.

Light switches seem to be one area. For example, the NICEIC document you cite above states: "The body of the switch must be installed outside of zones 0,1 and 2 but the pull cord itself is permitted to enter zones 1 or 2 providing it is of insulating material.", yet other documents frequently do not mention this.

Most sources explain that fixed equipment such as heaters etc. are allowed in zone 2, but then the advice seems to get a bit less consistent on things like FCUs (which often by implication go along with the fixed equipment). Take for example:

get: "Standard electrical wall fittings (such as wall sockets, flexible cord outlets and fused switches etc) are not IP rated so cannot be installed within zones 0, 1 or 2."

(note also the diagram on the above page (and others like it) show the hand basin extending zone 2 by its envelope + 0.6m - but then states "Basins are not covered, however they are usually considered to be Zone 2.")

[Andy Wade]

There is no IP requirement in Zone 3 - except "where water jets are likely to be used for cleaning in communal baths or showers" (in which case it's IPx5).

In a domestic bathroom normal wiring accessories (except socket-outlets) can be used in Zone 3. [OSG p. 59]

[Andy Hall]

NICEIC seem to take a different line:

"The NICEIC has received enquiries as to whether a wall-mounted light switch and other such accessories are permitted in zone 3. Regulation 601-08-01 does not preclude the installation of such equipment in zone 3. However, the general requirements of BS 7671 are applicable to locations containing a bath or shower and Regulation 512-06-01 calls for every item of equipment to be of a design appropriate to the situation in which it is to be used, or its mode of installation must take account of the conditions likely to be encountered. A normal wallmounted light switch and similar accessories may not have a degree of Ingress Protection (IP) appropriate for installation in zone 3 and would therefore not satisfy the requirements of BS 7671. The requirements of BS 7671 may be met by:

? installing a wall-mounted light switch with an IP rating suitable for its location, either in zone 3 or outside of zones 0, 1, 2 and 3, or

? using a pull-cord switch complying with BS 3676 with an IP rating suitable for its location. The body of the switch must be installed outside of zones 0,1 and 2 but the pull cord itself is permitted to enter zones 1 or

2 providing it is of insulating material."

The table on p59 of the OSG is misleading though, because the standard itself (601-06-01 clause iii) makes the point about IPX5 being needed if water jets are used as you said.

NICEIC seem to be referring to the generality of 512-06-01 and effectively say that this has precedence over the specific.

Hmmm.....

[Andy Wade]

Equally you can argue that BSI committee JPEL/64, responsible for the content of BS 7671, has seen fit to include specific IP requirements for zones 0, 1 and 2 in Section 601 of the standard but not for zone 3 and that, by implication, they consider that 'non-IP rated'[*] accessories /may/ be sufficient to satisfy reg. 512-06-01. I emphasise the "may" because there is, as always, an onus on the designer/installer to consider the specific circumstances and apply some common sense.

The NIC is of course perfectly at liberty to impose more specific requirements on its members. Perhaps it thinks its members lack common sense. (Evidence to that effect has certainly been posted here on occasion.)

You have a point there as the scope does not appear to exclude non-domestic bathrooms. The OSG is far from perfect, as noted here before.

I'm sure that's right, but of course it's all a matter of interpretation. The IEE guidance note on 'Selection and Erection' may also help here, but I don't have a copy up-to-date enough to include the revised (zones) version of Section 601.

[*] in the waterproofing context; other IP requirements will usually apply for protection against direct contact [regs. 412-03-xx].

[r.p.mcmurphy]

Do you know how these work?

Steve

[Andy Hall]

If you click on the link you get this page.

thing to note is that if you are using LV halogens then do make sure that they are dimmable with decent power supplies. GOOD QUALITY, they say....