Load calculations for bathrooms

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ESolar

Senior Member
Location
Eureka, CA Humboldt County
Occupation
Electrician/Contractor
A new California City residential load calculation sheet (using NEC 2020) includes 1,500 W for each bathroom circuit. This is my first time encountering an explicit demand for bathroom circuits. My understanding is that baths are part of the general square footage calculation (3 W/sqft). Including them explicitly double counts, and overstates their likely impact (barring multiple hairdressers operating on said premises). Is this a new thing? First time encountered.
 
ESolar said:
A new California City residential load calculation sheet (using NEC 2020) includes 1,500 W for each bathroom circuit.
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That would be in error.

For the standard calculation, 220.14(J)(1) tells you that the bathroom receptacles are general use receptacles already included in the 3 VA/ft^2 allowance, via the reference there to 210.11(C)(3).

For the optional calculation, 220.82(B)(2) calls out the circuits required by 210.11(C)(1) and 210.11(C)(2) as requiring a 1500 VA allowance. By omitting 210.11(C)(3) there, the clear implication is that bathroom circuits do not require a 1500 VA allowance, and are considered general use receptacles already included in the 3 VA/ft^2 allowance, just as in the standard calculation.

Cheers, Wayne
 
ESolar said:
A new California City residential load calculation sheet (using NEC 2020) includes 1,500 W for each bathroom circuit. This is my first time encountering an explicit demand for bathroom circuits. My understanding is that baths are part of the general square footage calculation (3 W/sqft). Including them explicitly double counts, and overstates their likely impact (barring multiple hairdressers operating on said premises). Is this a new thing? First time encountered.
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Is there a true written down local amendment to 220 if not it's just someone thinking they have a smart idea.
 
If they are insistent with documentation of code change. My response to the load sheet then would be to eliminate the bath square footage from the general calculation then add in the requested 1500W.
 
Fred B said:
If they are insistent with documentation of code change. My response to the load sheet then would be to eliminate the bath square footage from the general calculation then add in the requested 1500W.
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3w is for lighting and 1500w dedicated is for hair dryer. Hair iron …….
I think that make sence


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retirede said:
What if the hair dryer and iron are used at the same time?

If we start adding provisions for handheld appliances to load calcs, where does it end?
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Just go straight to the annex examples and show this not the case since all dwelling units require a bathroom therefor a bathroom circuit but don't have thr 1500 watts from a hair dryer on it.
 
Thanks everyone. I didn't think that there was anything new in this regard. We can add my heat gun, compressor, space heater, etc., and before you know it, I need a 400A panel.

And yet the only breakers that I have blown at home, for example, are (1) when I tossed the over the range micro and replaced it with a countertop micro, and had the toaster oven and micro on the same SBAC without thinking - I have since extended the dedicated micro circuit to avoid that issue, and (2) when I had a space heater in my office and the plugin hybrid car plugged into the exterior outlet tied to the same circuit - an oversight that I obviously don't do anymore. These were just mistakes, and they can happen in any home and thats why we have breakers.
 
So the AHJ insists that the code requires at least 1 x 1500 W for bathrooms. Other than the code itself, which appears explicit to me, is there an authoritative source with a summary of 220.82 that I can send to them for info. I figure it will save some people some money if they're on the edge of needing a new panel. Particularly with the push to electrify, it seems important to pursue and rectify. Maybe someone here that sits on the code making panel can chime in.
 
ESolar said:
So the AHJ insists that the code requires at least 1 x 1500 W for bathrooms. Other than the code itself, which appears explicit to me, is there an authoritative source with a summary of 220.82 that I can send to them for info. I figure it will save some people some money if they're on the edge of needing a new panel. Particularly with the push to electrify, it seems important to pursue and rectify. Maybe someone here that sits on the code making panel can chime in.
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Load calc books get 3 from different sources and show them that these are authorities in electrical education and that they don't support the ahjs unilateral interpretation. Then also anex D examples.
 
ESolar said:
So the AHJ insists that the code requires at least 1 x 1500 W for bathrooms. Other than the code itself, which appears explicit to me, is there an authoritative source with a summary of 220.82 that I can send to them for info.
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You can point them to Annex D Examples D1(a) and D2(a), which show the 1500VA allowance for the SABCs and the laundry circuit, but not for the bathroom circuits. Which supports my earlier answer.

Cheers, Wayne
 
It's interesting that 220.82(B)(2) references 210.11(C) where we get the SABC's for kitchen (1) and laundry (2), but it stops before we get to (3), the 20A circuit for the bathroom(s).
 
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