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isolator for bathroom fan

Discussion in 'Electrics UK' started by Yarn, 14 Jul 2010.

  1. Yarn

    Yarn

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    Hi, after reading the site, I am wondering what is the correct method for me to wire my bathroom extractor fan.

    I have a timed unit, which I have fitted and have tripple & earth exiting from.

    I want the fan to operate on its own switch and not run when the lights are turned on.

    Is it ok to use a double pole isolator in the ceiling, then from this connect the neutral to the fan, and the live to both the live fan and switched live fan?

    The issue is that i ahve been reading about using a 3 pole isolator but I am unsure if i need this, when I am not really having a swithced live from the lights.

    Many thanks.
     
  2. ban-all-sheds

    ban-all-sheds

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    If you don't have a 3-pole isolator, how will you isolate the permanent live to the fan if ever you need to?
     
  3. Yarn

    Yarn

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    Sorry, but I think we misunderstand each other, plus I cant answer your questions - your the expert!

    I am asking - can i use a 2 pole isolator as the control to turn the fan on / off. The fan will run for the timer because I have coneccted the switched live and permanet live to the fan togethor, and they are coming from the isolator.

    perm L & N -> isolator > fan (SL & L same connection), N

    Is this ok to do?

    Many thanks.
     
  4. ban-all-sheds

    ban-all-sheds

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    Yes it's OK.

    But the fan will not run on, because when you turn the switch off it will lose its permanent live supply.

    When off, there will be nothing coming out of the Load terminals on the switch, so your fan will have nothing connected to permanent live, nothing connected to switched live and noting connected to neutral.
     
  5. Yarn

    Yarn

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    Thanks for your help.

    I am hoping that when switch is turned on, fan will run untill timer stops fan. Next morning, i will turn the switch off, then on again to make it run.

    I would be happy if it works like this. AND CONFORMS to regs (hence the isolator).

    There is also the potential to upgrade the wiring at a later time and fit a 3 pole isolator in place and run from light if need be, but this is not my prefernce.

    ps, i did get my consumer unit replaced by a pro in the end!
     
  6. holmslaw

    holmslaw

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  7. Yarn

    Yarn

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    Please elaborate? Holmslaw.
     
  8. holmslaw

    holmslaw

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  9. Yarn

    Yarn

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    spot on mate:

    DX100T only
    • Operate the fan using the on/off switch. When
    the switch is turned off, the fan continues to
    operate for the adjustable time delay.


    Looks like i need an isolator and a switch :(

    Before any one asks, I do not want it to run when the light is turned on.
     
  10. ban-all-sheds

    ban-all-sheds

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    Look on the bright side - you only need a single-pole switch, which will be cheaper.


    What about a humidistat controlled fan, which will automatically switch on and off as required?

    Or will there be gases other than water vapour to remove from the room? ;)
     
  11. Yarn

    Yarn

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    LOL, but the trouble is I already bought the DX100T and fitted most of it in the wall!

    If i now use an isolator and a pull switch, it looks like i will have to pull the switch on then off for the timer to work?

    Im sure i fitted on of these in my last house and dont remember any of these problems.

    I might run it up and test it. I know some PIR lights will run on the timer from the first time power is on, maybe this is the same.
     
  12. ban-all-sheds

    ban-all-sheds

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    Yup - that's the way they work.

    The idea is that you turn them on when you start the activity which generates a need for extraction (e.g. a shower, a steamy bath, a whatever) and turn it off when you leave, whereupon the fan carries on running for a while to ensure that the extraction is well and truly done - e.g. if it stopped the moment you turned it off on leaving the room after a shower or a steamy bath or a whatever then there'd still be steam etc in the air.


    No - that's not how they work.
     
  13. flameport

    flameport

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    If you want the fan to be started when a cord is pulled, and run on the timer, then turn off, you need to get a retractive pull switch.
    These are a single pole switch with contacts which are only closed when the cord is pulled - releasing the cord opens the switch.

    Permanent L&N connect to the fan, switched L goes via the switch.
    The 3 pole isolator is just used to disconnect power from the fan for cleaning etc.
     
  14. NANOOOO

    NANOOOO

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    Having a problem with a fan

    Got a new vent axia with time delay

    Thought it would be a simple change over.

    Well i pull the cord it does not turn on :(

    But when i bridge the live and the s/l it comes on

    the fan has not got an isolator switch, it was a old installation.
     
  15. Taylortwocities

    Taylortwocities

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    You have a new, unrelated problem.

    Go and start a new topic of your own. Please don't hijack old ones.
     
  16. DIYnot Local

    DIYnot Local

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