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Wiring for Bathroom Exhaust Fan

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  • Wiring for Bathroom Exhaust Fan

    It is allowed by code to wire a bathroom extractor fan by tapping off an existing outlet or does it need a dedicated circuit and a breaker in the breaker box?

  • #2
    Re: Wiring for Bathroom Exhaust Fan

    Originally posted by blue_can View Post
    It is allowed by code to wire a bathroom extractor fan by tapping off an existing outlet or does it need a dedicated circuit and a breaker in the breaker box?
    Bathroom outlets are supposed to be dedicated. However you can run the fan off the lighting circuit for the bathroom lightning since it should be separate from the outlets. Does that help?

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    • #3
      Re: Wiring for Bathroom Exhaust Fan

      Yes I think that should work. However I guess I need to tap off at the light fixture since the light wall switch only contains the live wire correct?

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      • #4
        Re: Wiring for Bathroom Exhaust Fan

        Originally posted by blue_can View Post
        Yes I think that should work. However I guess I need to tap off at the light fixture since the light wall switch only contains the live wire correct?
        No, the wall switch has the switch leg (wire to light) also.

        You can tap into either one. Usually the overhead fixture is easier. Make sure there are not too many wires stuffed in the box(es).

        Also dont forget to use insulated exhaust piping in the attic to prevent condensation.

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        • #5
          Re: Wiring for Bathroom Exhaust Fan

          I looked at some fans and the installation instructions. They recommend running the fan on a GFCI protected circuit if the fan is to be installed within the shower enclosure - something I'm considering doing. Obviously one way wold be to run it downstream of one of the GFCI outlets but if this is not allowed the only option I could think of offhand is a new circuit from the breaker box using a GFCI breaker Do they make a wall switch with a GFCI that could be used if the wiring arrangement is going to be using the method suggested in this thread by tapping into the lighting circuit?

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          • #6
            Re: Wiring for Bathroom Exhaust Fan

            Originally posted by johncameron View Post
            No, the wall switch has the switch leg (wire to light) also.

            You can tap into either one. Usually the overhead fixture is easier. Make sure there are not too many wires stuffed in the box(es).

            Also dont forget to use insulated exhaust piping in the attic to prevent condensation.
            if you do that aren't both the existing light and the new fan controlled by the same switch? If that's what he wants that works, otherwise you have to add another switch.
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            • #7
              Re: Wiring for Bathroom Exhaust Fan

              Originally posted by Bob D. View Post
              if you do that aren't both the existing light and the new fan controlled by the same switch? If that's what he wants that works, otherwise you have to add another switch.
              Thanks for asking that question. I certainly do not want the existing switch to control the fan - I will be wiring a new switch and my question was asking if I can get at the hot and neutral from the existing switch. I did not think so myself but I was going to check after post #4.

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              • #8
                Re: Wiring for Bathroom Exhaust Fan

                If the light is fed from the light fixture, in your switch box you will have a cable with three conductors in it; a black wire, a white wire that should be re-identified as black, with a sharpie or black tape and a bare ground wire. You will not be able to feed your fan from the switch as stated in post #4 since there is no neutral. You will have to feed the fan from the light fixture and run a switch leg from the fan to your new switch.

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                • #9
                  Re: Wiring for Bathroom Exhaust Fan

                  How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)

                  BTW, You can tap into the bathroom receptacle as long as it does not feed anything outside of the bathroom.

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                  • #10
                    Re: Wiring for Bathroom Exhaust Fan

                    Originally posted by johncameron View Post
                    How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)

                    BTW, You can tap into the bathroom receptacle as long as it does not feed anything outside of the bathroom.
                    Yes sorry I was trying to gather info for doing this but in actual fact I'm out of the country at the moment (and in fact started this thread while away) and was using some of my spare time to gather some info - that's why I have not actually been able to physically look at anything.

                    I will actually be able to look at things when I return tomorrow.

                    My preference would be to use the downsteam connection of the GFCIs - I need to open and double check but I do not believe it feeds anything outside the bathroom. If that's allowed by code that's what I would prefer to use over tapping off the lighting circuit.

                    Comment


                    • #11
                      Re: Wiring for Bathroom Exhaust Fan

                      Originally posted by johncameron View Post
                      No, the wall switch has the switch leg (wire to light) also.

                      You can tap into either one. Usually the overhead fixture is easier. Make sure there are not too many wires stuffed in the box(es).

                      Also dont forget to use insulated exhaust piping in the attic to prevent condensation.
                      A switch leg has no neutral even though the installing electrician may have failed to re-identify the white wire as a hot leg.
                      How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)

                      BTW, You can tap into the bathroom receptacle as long as it does not feed anything outside of the bathroom.

                      Just because you have a white wire does not mean you have a neutral. Can you cite NEC for your statement about tapping into a DEDICATED circuit for a bathroom?

                      How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)


                      I think I told him that when I said look to see if you have one cable coming into the box.

                      If the fan is to be placed within the footprint of the tub/shower enclosure it must be GFCI protected. You could run a feed from your panel and install another GFCI receptacle or a GFCI breaker in the panel and feed from there to a switch and from there to the fan

                      Comment


                      • #12
                        Re: Wiring for Bathroom Exhaust Fan

                        I'm now in a position to actually physically look at things but since it seems almost certain that this will be installed within the shower enclosure and as such requires GFCI protected wiring it seems like I will have to resign myself to creating a new circuit from the breaker box to the fan. Not what I really wanted to do but it has to be to code as it will need to be inspected.

                        I only have one slot left in the breaker box as there were never many left to begin with and I've added extra circuits over the years for various things.

                        I will double check with the NEC and possibly the local inspector about this issue since there does not seem to be 100% convergence in thinking on this matter on this thread.

                        Comment


                        • #13
                          Re: Wiring for Bathroom Exhaust Fan

                          Originally posted by killavolt View Post
                          A switch leg has no neutral even though the installing electrician may have failed to re-identify the white wire as a hot leg.
                          How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)

                          BTW, You can tap into the bathroom receptacle as long as it does not feed anything outside of the bathroom.

                          Just because you have a white wire does not mean you have a neutral. Can you cite NEC for your statement about tapping into a DEDICATED circuit for a bathroom?

                          How about just taking the switch plate off and peeking in to see if there is a white wire? (insteas of us guessing where its feed from.)


                          I think I told him that when I said look to see if you have one cable coming into the box.

                          If the fan is to be placed within the footprint of the tub/shower enclosure it must be GFCI protected. You could run a feed from your panel and install another GFCI receptacle or a GFCI breaker in the panel and feed from there to a switch and from there to the fan
                          Yes, 210.11(c) 3 exception " Where the 20-ampere circuit supplies a single bathroom, outlets for other equiptment shall be permitted to be supplied in accordance with 210.23(a)1 and (a)2."

                          Can you cite where it says "Dedicated"?

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                          • #14
                            Re: Wiring for Bathroom Exhaust Fan

                            Good idea to talk to the inspector first, there might be local codes that apply. If the fan is recessed above the shower enclosure it does not need gfci protection but the instructions usually say it requires it, so you have to follow the instructions.

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                            • #15
                              Re: Wiring for Bathroom Exhaust Fan

                              I looked at the outlets in the bathroom - there are in fact two - one of them being the GFCI and the other fed off the first GFCI. I tested the outlet without the GFCI with my tester and the GFCI on the first outlet trips when the button is pressed on the tester. But as per the code mentioned above it references additional outlets - the question is would a bathroom fan be considered an outlet.
                              Last edited by blue_can; 08-08-2012, 01:37 PM.

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