I would like to add bathroom fans in bathrooms #1 and #2 (see drawings). There are currently no fans. I believe the existing bathroom circuit layout is not up to code so I am looking for the best way to add these fans.

I live in Nevada (Washoe County) and the 2011 National Electrical Code applies to me.


Please see the following drawing where I have detailed how everything is currently laid out. The layout is just based on my understanding from turning the breakers on/off and pressing the "test" buttons on the GFCI outlets. I don't specifically know the order things are wired.

My understanding is that this is not compliant because several bathroom lights and receptacles are on the same circuit (#2 in the drawing) and there are non-bathroom receptacles on the circuit (per 210.11(C)(3)). I also believe that if I added something to this circuit I would have to bring it up to code, correct? Do you have any opinion on if it is safe to leave it how it is?

So, since I believe I cannot add the new fans to circuit #2, I am considering adding them to circuit #1 (see second drawing). My reading of the electrical code is telling me this is allowed, could you confirm this?

Drawing #1: Current circuit layout: Current circuit layout

Drawing #2: Planned circuit layout: Planned circuit layout

Summary of questions:

  1. If I added something to circuit #2 in the drawing I would have to bring it up to code, correct?
  2. Do you have any opinion on if it is safe to leave circuit #2 how it is now?
  3. Is it legal and a good idea to add the fans to circuit #1?
  • Is Circuit Breaker #2 a 15 or a 20A breaker, and is the wire on that circuit 14AWG or 12AWG? (Turn off the breaker before opening up the boxes, of course.) Jan 2, 2017 at 18:05
  • Also, how much rewiring are you willing to do? Jan 2, 2017 at 18:06
  • @ThreePhaseEel They are 20A breakers, I pulled the master bedroom light switch out and the wire going to/from it is 12AWG so I'll assume the whole thing is 12AWG (I will verify that once I go to actually make changes to the circuit). I am willing to do as much rewiring as needed to safely accomplish the objective (whether I do the work or hire someone). If the existing bathroom circuit is safe (albeit not up to code) I'd like to leave it as is. If it is not safe I assume the recommendation will be to rewire the hallway/bedroom receptacles and bathroom lights onto circuit #2 while I'm at it?
    – Tim Sweet
    Jan 2, 2017 at 19:43
  • The bathroom light wiring is also 12AWG, so again lets assume it is all 12AWG.
    – Tim Sweet
    Jan 2, 2017 at 19:56
  • Is there a reason you aren't putting a fan in Bathroom #3? Jan 2, 2017 at 20:03

1 Answer 1


Answering your questions in turn:

  1. Yes, you would have to bring Circuit #2 up to Code if you altered it. The applicable provision is actually E3401.4 of the International Residential Code as your jurisdiction doesn't use the Annex H model legislation to adopt the NEC.

  2. The primary hazard the current wiring poses is that tripping Bathroom 1's GFCI turns the lights out on the unsuspecting occupant of Bathroom 2, which could lead to a minor disaster (say involving a hot curling iron, or stumbling and falling in the shower in the dark).

  3. Adding the fans to circuit #1 isn't a problem, by Code -- bathroom outlets other than the required receptacles serving the countertops can be on any general-use branch circuit. With a fair bit of rewiring, though, it's possible to juggle things so that the bathroom lights and non-bathroom receptacles move to circuit #1 while the bathroom receptacles stay on circuit #2, which would make things almost fully Code-compliant (bathroom #3 would need to be addressed separately, but that's simply a matter of putting a new breaker in the panel and moving bathroom #3's homerun to it, based on your diagrams).

  4. Last but not least, you don't need a divider to put two different circuits in the same wallbox as the voltage between adjacent devices can't exceed 300V on a residential 240/120V service. The requirement for dividers between circuits in mains-only boxes only kicks in for commercial folks and their 277V lighting circuits, see NEC 404.8(B) for details.
  • Thanks! That answers my questions. I will consider your additional recommendation in part 3 as well.
    – Tim Sweet
    Jan 3, 2017 at 0:49
  • Regarding the code adoption, could you clarify what you mean by the NEC isn't adopted? My understanding from the Sparks Municipal code is that it was adopted, source: municode.com/library/nv/sparks/codes/…
    – Tim Sweet
    Jan 3, 2017 at 0:50
  • 1
    @TimSweet -- Annex H of the NEC contains a set of model adoption regulations written by the NFPA that an Authority Having Jurisdiction can use "as is". However, like many US localities, your city adopts the NEC by reference without including the Annex H clauses, as it's used to supplement the IBC and IRC, both of which incorporate the NEC by reference and contain their own supplementary implementation clauses. (It appears that Sparks uses the International Building Code's model adoption regulations, which don't touch on electrical-specific stuff, unlike NEC Annex H.) Jan 3, 2017 at 1:01

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