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  1. #1
    Join Date
    Apr 2011
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    Default Light Switch Controls All Downstream Connections

    When I turn on the powder room fan, all downstream connections on that circuit (two ceiling lights and a double outlet) are switched off. The powder room light is on the same circuit but it stays on, so I assume that it is upstream. Is this a wiring problem or is the fan pulling too much power? I need to know if this is a dangerous problem that needs immediate repair or if it's just an annoyance.

  2. #2
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: Light Switch Controls All Downstream Connections

    Question --- is the receptacle normally live without the lights on ?

    If not --- and as crazy as it sounds --- check the *fan* switch to see if it's a 3-way switch.

    If so -- the lights and receptacle that turn off are wired to one of the *traveller * connectors -- the fan is wired to the other *traveller* connector --- the supply feed is jumperd from the light switch to the *common* of the 3-way .
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Feb 2011
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    Brown county, Ohio
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    52

    Default Re: Light Switch Controls All Downstream Connections

    canuk, that is crzy. but it makes perfect sense. lol.

  4. #4
    Join Date
    Aug 2007
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    Default Re: Light Switch Controls All Downstream Connections

    Edgeking -- it is crazy .
    Whether or not it's the case here is unknown -- I've run into a very similar scenerio once before -- had me scratching my head in wonderment -- and thought it worth mentioning.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  5. #5
    Join Date
    May 2008
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    Pacific Northwet
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    1,608

    Default Re: Light Switch Controls All Downstream Connections

    Do the downstream lights seem dimmer than normal? Even when "off" does the fan turn, slowly? If so, it could be that someone wired in the downstream lights and receptacle by just tapping in to the wires at the switch, without a proper understanding of electricity and wiring.

    So when the switch is off, the lights and outlet are wired in series with the fan -- that is, the electricity has to flow through the fan motor in it's path through the lights. When you turn the switch on, it "shorts" the lights & outlet, so the fan turns at full speed and no electricity flows through the light.

    It seems a bit far-fetched, since a fan typically has a lower wattage (higher resistance) than a light bulb (lower resistance). If this were the case, I'd expect the fan to speed up as more lights were turned on downstream, and each light added would make the other ones dimmer.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  6. #6
    Join Date
    Apr 2011
    Posts
    2

    Default Re: Light Switch Controls All Downstream Connections

    Thanks for the input, folks. To answer fencepost's questions, yes the outlet is live when the fan is off and no, the fan does not turn at all when the switch is off.

    Canuk, the outlet is live (both upper & lower sockets) when the fan switch is off; both are dead when it's turned on. I had three switch-controlled double outlets upstairs that were wired wrong, so that both outlets were controlled by the switch instead of just one so that thought did occur to me but I couldn't figure out how it work (or how it should work if wired correctly). My only experience with 3-way switches is where you have two at opposite ends of the room controlling the same light fixture. Seems odd that you'd use a 3-way switch to control a bathroom fan, but it could have been a mistake or that's the only kind of switch the electrician had left when he was doing the wiring ... stranger things than that have happened. I'll have to check the switch and see if it's single pole or not.

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