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I intend to replace an old bathroom fan with a Panasonic WhisperGreen Select model that includes a fan, a light, and a nightlight. I have several questions.

The setup:

  • The existing fan is on a 20amp circuit, but the lines between the switches and the fan (light and fan are separate switches) are 14 gauge, not 12. There is nothing else on this circuit.
  • The bathroom has mirror vanity lights on a different 15amp circuit. It also has a GFCI outlet on this circuit. This circuit also powers a few overhead lights in another room (not in the bathroom).

The simplest thing for me would be to move the outlet to the 20amp, and everything else (mirror lights, fan, and fan lights) to the 15amp. Would this be allowed?

Some related questions:

  1. By code, am I even allowed to power the fan from either of the two circuits? i.e. could it share with the outlet circuit (my understanding is outlets in baths can't share) or could it be placed on the lighting circuit (again, I believe the answer is no...but this I'm not sure about. The fan draws only 0.27A)?
  2. Am I allowed to power the WhisperGreen's lights with the shared 15amp lighting circuit?
  3. If the fan remains on the 20amp circuit, I assume I am required to upgrade the 14/3 between switch and unit with 12/3?
  4. Can this situation be wired with just the existing circuits, or is a third going to be required to do it fully by the book?

I suspect that a simple fan replacement would be grandfathered and wouldn't require updating to code, but my preference would be to make it right while it has my attention.

What would you suggest doing if you were in my shoes? One thing I would particularly like to do is get the 14ga wire out of the 20amp circuit...powering the fan and lights with the 15amp lighting circuit would accomplish this.

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  • Because you've seen 14ga wire on the circuit, you really need to change out the breaker to a 15A. Unless you can inspect all the wire back to the panel you kind of have to assume there's more 14ga.
    – JPhi1618
    Oct 22, 2021 at 20:45
  • What country are you in? Oct 22, 2021 at 21:01
  • 14 gauge can't be on 20 amp breaker, that's a no-no. Doubt very much if the fan and light even comes close to needing a 20 amp breaker, so a 15 amp breaker should work, if code allows. Do think the outlets must be 20amp circuit with 12 gauge wire and GFCI protected.
    – crip659
    Oct 22, 2021 at 21:16
  • @JPhi1618 - I am 95% sure that the romex goes from breaker directly to the existing fan, with no junctions in between. Good point though - if I cannot confirm this, I need to change to 15A breaker Oct 22, 2021 at 23:46
  • @Harper-ReinstateMonica - I am in USA Oct 22, 2021 at 23:46

1 Answer 1

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It seems like your plan will work to bring up to current code. Some details in communication can be missed, so here are the most relevant current (2020) NEC code sections that I think are relevant. When reading these sections keep in mind that in NEC terminology an "outlet" is any equipment connection point including hard wired connections, and a "receptacle" is a specific type of outlet.

210.11(C)(3) Bathroom Branch Circuits. In addition to the number of branch circuits required by other parts of this section, one or more 120-volt, 20-ampere branch circuit shall be provided to supply bathroom(s) receptacle outlet(s) required by 210.52(D) and any countertop and similar work surface receptacle outlets. Such circuits shall have no other outlets.

Exception: Where the 20-ampere circuit supplies a single bathroom, outlets for other equipment within the same bathroom shall be permitted to be supplied in accordance with 210.23(A)(1) and (A)(2).

210.52(D) In dwelling units, at least one receptacle outlet shall be installed in bathrooms within 36 in. of the outside edge of each basin. The receptacle outlet shall be located on a wall or partition that is adjacent to the basin or basin countertop. These receptacles shall have GFCI protection as required by section 210.8(A)(1).

The words "work surface" in 210.11 is a recent addition, it used to apply/allow all bathroom receptacles. There is no section that says fans or lights in a bathroom require 20A circuits.

210.23(A)(1) says cord and plug connected equipment not fastened in can't use more than 80% of the branch circuit rating and (2) says fastened in place equipment other than lights cant use more than 50% of a circuit when circuit is shared with receptacles.

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  • So, bathroom lighting circuit does not need to be confined solely to bathroom (it can also provide power to lights in other rooms?)? Oct 22, 2021 at 23:48
  • I am sorry to be dense about this - does the Exception to 210.11(C)(3) mean that the 20A circuit that supplies receptacle outlets could ALSO supply my fan (which is an "outlet" if I am understanding correctly?)? (this 20A circuit supplies only this bathroom). I don't think I will go this route if I can run fan from 15A circuit instead, but I'd like to know for sure. Who knows what I'll find when I get started... :) Oct 22, 2021 at 23:52
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    It is normal for bathroom lights to share with other lights. Oct 22, 2021 at 23:53
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    Yes, if supplying one bathroom the exception allows fans, and it is commonly done that way. Oct 22, 2021 at 23:55
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    Thank you very much - I have accepted this as the answer. I am glad to learn that I was incorrect in my thinking that bathroom lighting circuits could not be shared elsewhere. I think I was confusing them with the rule for bathroom outlet receptacles. Oct 22, 2021 at 23:57

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