IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Fan Isolation Switch
Topic Summary:
Created On: 11 November 2017 09:46 AM
Status: Read Only
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 11 November 2017 09:46 AM
User is offline View Users Profile Print this message



pal1952

Posts: 9
Joined: 30 October 2017

I am about to start the rebuild of an en-suite shower room, none of the wiring for it comes anywhere near regulations!

The normal position for the isolation switch would be over the door. Unfortunately the wall (cinder block) above the door has been disturbed in the past and I do not want to start hammering at it. Is there anything that says the switch cannot be offset from the door centre by around 1M but still at high level. Ideally it would be in the loft but I don't think that would conform.

I also intend to put the feeds to the low voltage power supplies on the isolation switch, I presume this is acceptable.

Cheers
 11 November 2017 10:02 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 16007
Joined: 13 August 2003

BS 7671 isn't anything like as draconian as far as isolation is concerned as you seem to fear - basically isolation can go anywhere suitable, the only condition being that if it wouldn't be under the control of someone working on the equipment it supplies then it must be capable of being locked off.

That said there's no particular requirement for simple fans to have individual isolation either - certainly it's good practice and very convenient for maintenance when its on the lighting circuit to keep the light on when working (either in a room without windows or if maintenance happens after dark). If service conditional allow, the MCB or even installation's main switch could be claimed to provide isolation without BS 7671 objecting.

So as long as you respect the shower/bath zones you can put the fan isolator anywhere you like in the room, or even outside if it's the type that allows locking off (some conventional looking 3-pole fan isolators do now that that facility).

- Andy.
 11 November 2017 10:31 AM
User is online View Users Profile Print this message



mapj1

Posts: 9568
Joined: 22 July 2004

do you mean fan or shower isolator ? Pull cord switch is common for the latter. As above, the fan isolation can go almost anywhere dry more than 2 feet from the shower area, so long as you can see if someone goes to operate it when you are cleaning/ working on the fan.
What is your low voltage (do you mean 12V ?) used for - lights fans pumps ? you may need to think a bit about what goes off together or separately.

-------------------------
regards Mike
 11 November 2017 11:31 AM
User is offline View Users Profile Print this message



WiredScience

Posts: 321
Joined: 25 January 2012

You could fit a ceiling mounted fan isolator.

Google "cord operated fan isolator" and TLC will pop up with offerings from several manufacturers.
 11 November 2017 03:29 PM
User is offline View Users Profile Print this message



aligarjon

Posts: 3868
Joined: 09 September 2005

Or use an in-line fan, then the whole lot can go in the roof.


Gary

-------------------------
Specialised Subject. The Bleedin Obvious. John Cleese
 11 November 2017 09:04 PM
User is offline View Users Profile Print this message



pal1952

Posts: 9
Joined: 30 October 2017

Thanks for all the comments. I would prefer to be able to isolate everything inside the room, fan, lighting, illuminated/heated mirror. The fan will be an inline one and the lighting 12V however I'm not sure about the illuminated/heated mirror. The illuminated/heated mirror has not been chosen so far but I presume that this will be 240v, I guess that putting it in an earthed metal box with no switches that can be touched directly will satisfy the zone rules. I understand the comment about considering what you are turning off. The lighting will be all led and fed from a 12V DC power supply, the power supply is probably the least reliable so it seems to be wise to isolate this as well.
Bottom line as there doesn't seem objection to re positioning the isolation switch then that is what I will do. It will be outside of the shower room at high level and 1M to the right of the door.
Once again thanks for the comments, all constructive and polite, not something that is seen too often on forums. Long may it last.
 11 November 2017 09:44 PM
User is online View Users Profile Print this message



geoffsd

Posts: 1760
Joined: 15 June 2010

Originally posted by: pal1952

The illuminated/heated mirror has not been chosen so far but I presume that this will be 240v, I guess that putting it in an earthed metal box with no switches that can be touched directly will satisfy the zone rules



I'm not sure what you mean exactly but that doesn't sound like a good idea.
The fewer earthed metal parts there are in a shower room, the better.

The zones only extend 600mm. from the open edge of a shower cubicle so it's doubtful that the mirror will be in a zone.
However, if suitable for the environment and location according to the manufacturer, putting it in anything is unlikely to be necessary.
 12 November 2017 07:26 AM
User is offline View Users Profile Print this message



pal1952

Posts: 9
Joined: 30 October 2017

Reply to geoffsd

Sorry my explanation of the mirror was bad. I have have a look at the available mirrors and they come with the active guts of the mirror (power termination, power supply, heater, electronics etc) inside a metal (sometimes plastic) case onto which the mirror is mounted. Its a wet room so no definable end to the water however the mirror will be around 1M away from the nearest splash point, 1.7M from the shower head. Having done some splash tests the chances of the mirror getting wet from the shower are pretty much zero.

You say "The fewer earthed metal parts there are in a shower room, the better" is this because of the potential for shock if the earth fails?
 12 November 2017 12:59 PM
User is online View Users Profile Print this message



geoffsd

Posts: 1760
Joined: 15 June 2010

"The fewer earthed metal parts there are in a shower room, the better"

I only wrote "in a shower room" because that is what you are dealing with and the increased risk for wet people.

It is equally valid anywhere.

Earthing is necessary where there is exposed metal which may become live, in order to disconnect the supply in the event of a fault - but it also creates a low impedance path to earth which is undesirable should a person contact it simultaneously while receiving a shock from something else, also when not bathing.
Class 2 items are deemed safer because it removes both of these possibilities.
It would be better to have no earthed metal anywhere but this would be laborious and costly to achieve.

Whatever the appliance, I cannot think of an instance when "putting it in an earthed metal box" would be a wise thing to do.
 12 November 2017 02:33 PM
User is offline View Users Profile Print this message



Fm

Posts: 1733
Joined: 24 August 2011

Originally posted by: aligarjon

Or use an in-line fan, then the whole lot can go in the roof.





Gary



In agreement with Gary, I would rather not see a wall fan, much prefer a ceiling grill and an in-line fan, if there is a loft space of course.
 13 November 2017 02:14 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 16007
Joined: 13 August 2003

Its a wet room so no definable end to the water

The zones are still very precisely defined - zone one extends to 1.2m from the fixed water outlet (and there is no zone 2).

I would prefer to be able to isolate everything inside the room, fan, lighting, illuminated/heated mirror.

Humm, the usual reason for having a fan isolator is to be able to leave the lights on when working on the fan - having one single isolator for the lot defeats that - you (almost) might as well have no local isolator and just switch off the lighting MCB.

- Andy.
 13 November 2017 03:49 PM
User is offline View Users Profile Print this message



JZN

Posts: 789
Joined: 16 November 2006

I'm pretty sure you'll find those bathroom lit/heated mirrors are IP rated for splash areas the same as electric shower units. They have a rubber seal around the box rim which seals it all up once you place the glass front onto the box.

John
 13 November 2017 10:37 PM
User is offline View Users Profile Print this message



pal1952

Posts: 9
Joined: 30 October 2017

JZN - Yes, the mirror (Eras LED Illuminated Mirror) is IP44 so should be fine .
AJJewsbury - OK on the not putting the lighting on the isolation switch. The lighting being fed from a switched mode power supply in the loft does bother me a bit (although I do mount such things on a small piece of plasterboard just in case). Loft fires are a disaster as they are not discovered until it is far too late.
Statistics

New here?


See Also:



FuseTalk Standard Edition v3.2 - © 1999-2017 FuseTalk Inc. All rights reserved.

..