Can I use a single 20A circuit for two bathrooms?

Question

Can I put two bathrooms on one 20amp breaker for the respective outlets or do I need a separate 20amp circuit for each bathroom? I am running out of panel space in my subpanel otherwise I would just run a home run from the subpanel to the bathroom no big deal. I am located in Connecticut USA.

Answer 1

Ed Beal's post covers a major point... here's a little backgrounder on that. A 20A breaker @ 120V will supply 2400 watts nominal. "Sounds like plenty, what could 2 bathrooms possibly use?"

Well, one hair dryer is between 1500 and 1800 watts.

So while it's perfectly legal for any number of bathrooms to share 1 electrical circuit (one McMansion was built with 5 bathrooms on 1 circuit)... it's a bad idea from a usability standpoint.

So really, decide. What is the purpose of doing electrical wiring? To serve yourselves. If you're trying to barely comply with Code to get inspector sign-off so you can flip the house, then 5 bathrooms on 1 circuit makes sense. However if you're gonna live there, then the first rule of electricity is: "It's there to serve me, and do my bidding". So install the electrical service that you want.

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Now, as far as that full panel, first, if you're full it's surely less than 40 spaces. If so, it surely allows at least enough tandem/double-stuff breakers to make it to 40... so that's an option. Also, in the LED age, lighting circuits don't need the ampacity they once did - if you have several lighting circuits, you may be able to consolidate them onto one breaker.

Also, bathroom hardwired loads can be on any 120V circuit of any kind (except the dedicated circuits to kitchen, laundry, garage or bathroom receptacles, or furnace. And they are allowed on the bathroom recep circuit if that serves only this same bathroom). So it may be possible to recover spaces by diffusing those loads onto other nearby circuits.

Lastly, you can do what you really, really ought to do... and that's fit a big subpanel today so that you are ready later when you want to add other circuits. You don't want to let opportunity after opportunity pass you buy - hot tub (can't) heat pump (no spare spaces) floor heat, electric vehicle, 240V welder at a great price, have to turn 'em all down. Again back to "Electricity serves us".

Answer 2

The answer is yes a single circuit can supply everything in a single branch circuit

OR

The receptacles only for multiple bathrooms.

NEC 210.11.C .3 & the exception allow for the above statement in both the 2017 & 2020 code.

I have seen this code taken to an extreme 3 bathrooms only receptacles. The owner was trying to save $ and would not budge as code allowed it.

I was back adding 2 more breakers new wire at a much higher cost, 3 girls 3 curling irons or hairdryers will trip a 20 amp every morning.

Don’t go more than 2 and make sure the wife and kids are not fixing there hair at the same time because it could be close. (Only receptacles allowed in the bathrooms) no other receptacles or other devices on that branch circuit.

Answer 3

Yes, you can put more than one bathroom on a 20 amp circuit for outlets, but nothing else can be on that circuit other than bathroom outlets. But bear in mind that if 2 people are using each bathroom at the same time, one with a space heater and another with a hair dryer, you could easily trip a breaker.

Answer 4

One potential gotcha here is with GFCIs. In a normal circuit, you put receptacles in series with one another. But you really don't want to do that with a GFCI where another room is on the LOAD side because if you wire them up like that, Bathroom #2 might be the trip for an event in Bathroom #1, and you might not want to have to leave the bathroom to reset a GFCI in another bathroom. If you do elect to do this, be sure to make your GFCI receptacles are on their own branch off that single 20A line. Pricier, but you'll save yourself a lot of headache having them tandem to each bathroom.