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Electrical - Two switches for light and vent fan

Post in 'DIY and General non-hearth advice' started by grandyellow111, Apr 6, 2013.

  1. grandyellow111

    grandyellow111 Member

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    In my bathroom I have one vanity light and one vent fan (to remove moisture). There is one switch that turns on both the vanity light and the vent fan. I want to add another switch, right next to the existing switch, in a double box to separately control the light and the vent fan. My understanding is that I do not have to run any additional wires. Instead, I just need to get a bigger box and another switch and connect the wires as shown below. Is this correct?

    [​IMG]

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  2. fossil

    fossil Accidental Moderator Staff Member

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    Yes. Make sure you always connect the black ("hot") wire through the switch. Always, always, always. Neutrals (white wires) ganged together. Ground wires (bare copper) ganged together. Not difficult, but can be dangerous (like life-threateningly dangerous)...make sure you know what you're doing before you do it...and don't do anything to anything unless you've verified that it's dead (multimeter, circuit tester, whatever). There are also code requirements that detail how many of what gauge wire connections are allowed in a junction box of a certain cubic inch capacity. Any doubt about what you're doing...get a professional to come take a look. Rick
  3. Gary_602z

    Gary_602z Minister of Fire

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    Should be okay unless the fan and light are switched on a single switch leg?

    Gary
  4. grandyellow111

    grandyellow111 Member

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    I am not sure what is meant by a "single switch leg."
  5. seige101

    seige101 Minister of Fire

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    If you really wanted to make it easier just purchase a stacker switch and put it into the existing box.

    [​IMG]

    That if if the fan and vanity light both have their wires originate in the same switch box. Some guys will go from the switch to the vanity light and then to the fan it self. If that is the case you would require some re-wiring.
  6. fossil

    fossil Accidental Moderator Staff Member

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    Yeah, that "stacker switch" is a great space-saving (labor-saving) option if the existing box will accommodate it. That would be my preferred configuration if there's nothing precluding it. Rick
  7. grandyellow111

    grandyellow111 Member

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    Okay. I get it. That may be what I have. I haven't taken the cover off yet to see if there is a separate wire going to the light and a separate wire going to the fan. Thanks for the suggestion on the double stacker switch (assuming I already have a separate wire going to each destination).
  8. Gary_602z

    Gary_602z Minister of Fire

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    Here is an example of a switch leg. In this case the white wire at the switch is hot and must be marked. You will need to know what size box you have and how many wires are running into it.

    Power-in-to-light-switch-leg-to-switch.gif
  9. seige101

    seige101 Minister of Fire

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    Thats a switch loop
  10. TradEddie

    TradEddie Minister of Fire

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    That's what I did, simple and quick. Lots of warnings on the box saying that it must be installed in a double gang box, which makes no sense (why would you need this switch if you had a double gang box?), so I assume that means it isn't always (ever?) up to code. That switch loop arrangement sounds like a great way to electrocute the next person to open the box. Reminds me that I'm right to be paranoid - switch off breaker, check with tester, and before touching anything, short the wires, just in case the tester is broken.

    TE
  11. fbelec

    fbelec Minister of Fire

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    g yellow if you are still a little unsure pull the switch plate off and pull out the switch. you do not need to disconnect anything at this time. once you have the plate and switch out tell us how many cables are in that box (one cable will have a black a white and maybe a red depending on how it was set up and depending on how old your wires are a optional bare wire for ground.) so we need how many cables in the box and what color wires from each cable connect to what. also while you are there measure the depth of the box and width. also is the box metal or plastic. that will dictate how many wires are allowed in the box. the size of the wires also does but i don't think you will be able to tell me that so we will say they are 14 gauge because 90% of residential light circuits are 14. i'd say we could tell by the breaker or fuse size but in my exp. i find the wrong size breakers on the circuits more than half the time i pull off a panel cover.

    frank
  12. basod

    basod Minister of Fire

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    As noted above pull the switch plate and see what is in the box if 1 piece of two conductor romex (black, white, bare ground)
    If this is the case your plans are foiled unless you know the run is in a joist and you can reach the turn - otherwise you will be opening up sheetrock.

    If the bathroom has an unfinished attic space above pulling new wire will not be that hard
  13. oldspark

    oldspark Guest

    The last time I read a code book that was totaly leagal (switch loop) checking for voltage first before working is a must.

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