Switching an exhaust fan

Discussion in 'The Projects Forum' started by Roar Power Electrics, Aug 9, 2012.

  1. Roar Power Electrics

    Thread Starter New Member

    Aug 9, 2012
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    I need to start an exhaust fan for toilets in a commercial building
    There are four toilet areas and assume the lighting for these toilets are fed from different circuits.

    Scope of works is that when any of the lights are on they need to start to the toilet exhaust fan.

    Any suggestions/diagrams

    Cheers
     
  2. ultradimensional

    New Member

    Aug 8, 2012
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    Have you ever worked with relays before? I think this would be a fairly simple thing to do when incorporating relays tied into the light switch wiring.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    In the DC world, you'd just use 4 diodes to "OR" the signals together. If one of the four is on, the fan is on. Somebody here must know how to "OR" together AC sources. But not me.
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Relays? Relay coil in parallel with each light, and all relay contacts in parallel to switch th fan.
     
    #12 likes this.
  5. crutschow

    Expert

    Mar 14, 2008
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    So you want all fans to come on even when only one set of lights is on, or just the fan in the toilet with the lights on?

    If the latter then just connect the fan in parallel with the associated lights.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Isn't it against electrical codes to serve a bathroom from more than one circuit?
     
  7. #12

    Expert

    Nov 30, 2010
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    This is how to OR a triac...not that it would be my choice for this circuit.
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    nevermind.. its a few stipulations about a single circuit serving multiple bathrooms,etc.. not the other way around.


    This is a simple task for a few relays. But I still don't think thats how it should be done.. IMO there should be 1 "main" switch to turn on the main light in the bathroom (could be 3 or 4 way if multiple entrances) but you still should have 1 main switch which would turn on lights/fans
     
  9. #12

    Expert

    Nov 30, 2010
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    There are some rather large fans available...fans that could serve more than one bathroom in a commercial building. I see them in catalogs for my day job.
     
  10. wayneh

    Expert

    Sep 9, 2010
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    Your choice would be the relay solution? Just curious.
     
  11. #12

    Expert

    Nov 30, 2010
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    Yes. Relays abound in my truck, They are reliable and don't require soldering. I could whip this in 20 minutes, standing on a ladder.
     
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