Loading a 20 amp circuit breaker

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eeee

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The following loads are expected using a home energy guide for home energy consumption on one 20 amp breaker for my hotel room circuit I am designing (120/240volt, single phase):
? Television-250 Watts
? Microwave-1450 Watts
? Microfridge-300 Watts
? Coffee Maker-850 Watts
? 3 Lamps-180 Watts
? Iron-1100-Watts

Total: 4130 Watts. I am assuming a 0.8 P.F.

Using standard design engineering practice and the NEC, it would not be part of the calculation that all of these devices are on at the same time, but it would be considered that most of these devices are being used at the same time.

4130 Watts yields 43.02 Amps.

Can I load up a 20 amp breaker with this design?
 
Re: Loading a 20 amp circuit breaker

My 20 amp breaker is only for the receptacles. I have another breaker for the ceiling lights, heaters, fans, etc. and am not worried about them.

I am only worried about the receptacles.

I know the NEC says for lodge rooms, use 1 1/2VA per square foot. I assume this VA is just for the receptacles??
 
Re: Loading a 20 amp circuit breaker

First of all, why would you assume a 0.8 pf? All of the loads you list are essentially resistive in nature. The power factor would be close to unity. That gives you a total connected load (in terms of current) of 34.4 amps, and not 43.02.

Secondly, I think you are overloading that circuit. But that is a design-related statement, not a code-related statement. The code restrictions on maximum load on a receptacle do not apply to your situation. See 210.23.

But I believe that someone will be using the iron while watching TV and heating up dinner in the microwave. I suggest using at least two circuits for these loads.
 
Re: Loading a 20 amp circuit breaker

i concur with Charlie's statement about design. I see too many scenarios where the breaker is either at max or above; two breakers
 
Re: Loading a 20 amp circuit breaker

I can't imagine a design or situation where you would encouter this on 1 circuit anyway. The list you provided would seem practical only in a kitchen scenerio, if anywhere, and we are already required to have a minmum of two circuits there. In addition, most microwaves of that size have mfg. recommendations for a seperate circuit which brings us up to 3. Seems far more a theory type question than a practical one.
 
Re: Loading a 20 amp circuit breaker

Have you looked at 210.60?

210.60 Guest Rooms.
(A) General. Guest rooms in hotels, motels, and similar occupancies shall have receptacle outlets installed in accordance with 210.52(A) and 210.52(D). Guest rooms meeting the definition of a dwelling unit shall have receptacle outlets installed in accordance with all of the applicable rules in 210.52.

(B) Receptacle Placement. In applying the provisions of 210.52(A), the total number of receptacle outlets shall not be less than the minimum number that would comply with the provisions of that section. These receptacle outlets shall be permitted to be located conveniently for permanent furniture layout. At least two receptacle outlets shall be readily accessible. Where receptacles are installed behind the bed, the receptacle shall be located to prevent the bed from contacting any attachment plug that may be installed, or the receptacle shall be provided with a suitable guard.
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It sounds like the room is of the 'extended' stay type with a fully equipped but small kitchen.


Dwelling Unit. One or more rooms for the use of one or more persons as a housekeeping unit with space for eating, living, and sleeping, and permanent provisions for cooking and sanitation.
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I would think that would mean you must provide two 20 amp small appliance branch circuits in addition to the other circuits for the 'non' kitchen area.

I do not see you being able to supply this room with any less than 3 circuits.

The few extended stay rooms I have stayed in placed a small panel in the room to handle the number of circuits. I imagine one feeder supplied a number of these in the room panels.
 
Re: Loading a 20 amp circuit breaker

I neglected to mention that I am converting two rooms that each have a 20 amp breaker in to one suite with a kitchen. The two existing rooms have not kitchen and share a bathroom, but do have a mini fridge and microwave for each room.

My total number of circuits would be two. Since I need two circuits for the kitchen minimum and atleast another circuit for the receptacles, I can not service the receptacles with two 20 amp circuit breakers.

My lights, fan and air handler equipment are serviced by another breaker.
 
Re: Loading a 20 amp circuit breaker

I was not correct in stating kitchen. There is not formal kitchen. There will be a microwave and minifridge available in the room, but no formal kitchen. Therefore maybe I don't need two circuits dedicated for a kitchen and can service the whole room with two 20 amp breakers??
 
Re: Loading a 20 amp circuit breaker

Originally posted by pierre:
Bob
Wouldn't the room have to have permanent means of cooking to be considered as a dwelling unit?
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Yes I agree, but I have never seen definition of permanent means of cooking.

I know many here disagree but none the less IMO a microwave is a means of cooking and if the motel intends it to always be there it would be permanent.

I do not believe permanent means (or has to mean) bolted, screwed or otherwise attached to anything.

I base my opinion on the common usage of permanent and cooking.

Keep in mind the Hotel will list the fridge and micro as amenities for 'home' cooking.

If I was designing this I would surly find out what the AHJ thinks before getting too far into it.
 
Re: Loading a 20 amp circuit breaker

In Washington State, the presence of a microwave, or even a coffee pot, qualifies an area as a "kitchen." But I believe that is limited to the context of whether GFCI protection is needed for the receptacles. The NEC does not require two small appliance circuits for non-dwelling unit kitchens. So the issue boils down to whether the hotel room constitutes a "dwelling unit." And the issue of what is a "dwelling unit" boils down to what is, and what is not, "permanent provisions for . . . cooking."

I am among those who disagree with Bob on this one, though I admit I have vacillated on this question from time to time. For today, at least, I would not call a microwave "permanent." But I will note that a range would be "permanent," even though the range at my house is not bolted or fastened into place. I can pull it away from the wall and move it across the floor, without doing anything more than unplugging it. So where would I draw the line? A range surface or an oven makes the hotel room a "dwelling unit," and a microwave and coffee pot do not. Perhaps the line is drawn over what I can or cannot pick up and carry away.

Bob's advice about checking with the AHJ is probably you best next move.
 
Re: Loading a 20 amp circuit breaker

What does the liscensed professional engineer under whom you are working (and who is sealing your drawings) say about this issue?
 
Re: Loading a 20 amp circuit breaker

If that microwave does happen to be bolted down somehow (as many are in motel rooms), wouldn't your proposal be a 210.23(A)(2) violation?
 
Re: Loading a 20 amp circuit breaker

Originally posted by mdshunk:
If that microwave does happen to be bolted down somehow (as many are in motel rooms), wouldn't your proposal be a 210.23(A)(2) violation?
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If the other items aren't fastened in place, perhaps. But this is a hotel room.
</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Television-250 Watts</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Microwave-1450 Watts</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Microfridge-300 Watts</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Coffee Maker-850 Watts</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">3 Lamps-180 Watts</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">Iron-1100-Watts</font>
<font size="2" face="Verdana, Helvetica, sans-serif">Chances are everything is fastened in place in some fashion. If that is the case, then he can load his circuit such that if all his listed loads are on, he's at 100% of the branch circuit rating.

But I agree with your thought, he can't jump over to other areas and supply general purpose branch receptacles with that same circuit. All 8 items would have to be 10 amps or less. :p
 
Re: Loading a 20 amp circuit breaker

Originally posted by georgestolz:If that is the case, then he can load his circuit such that if all his listed loads are on, he's at 100% of the branch circuit rating.
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250 + 1450 + 300 + 850 + 180 + 1100 = 4130 W.

4130 / 120 = 34.4 amps.

Which of these "listed loads" (i.e., loads from his list) are you omitting, when you say they add up to 100% of a 20 amp circuit? :confused:
 
Re: Loading a 20 amp circuit breaker

I have been following this thread and I am confused on three points.

1. If we know the rating of the equipment to be connected, why dont we have to size the circuit based on the namplate rating?

2. Is it ok to size these loads at 100 percent.

3. From an engineering standpoint, (and a business standpoint), why would you want to put so much equipment on a circuit as to almost guarntee nusance tripping?
 
Re: Loading a 20 amp circuit breaker

one thing it do bother me a bit here about the devices that you will be using in motel room are the devices listed will all be on the same time ?? if so then it have be on min of two circuits other wise i rather run in 3 circuits

one instering twist about this one it dont list anything about bathroom which i know some area will listed separed circuit with gfci yeah i know that but for iron where that will be hook up ??

i hope the person ask this question will understand in the moring when the motel renters will get up and will run almost everything on the same time it will load up the system pretty good there

Merci , Marc
 
Re: Loading a 20 amp circuit breaker

Originally posted by frenchelectrican:. . . in the morning when the motel renters will get up and will run almost everything on the same time it will load up the system pretty good there.
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Very good point. Anytime the NEC gives us demand factors, it is allowing us to install less capacity than would be needed to run absolutely everything at the same time. The clear assumption is that the owner (or renter) is not likely to run everything at the same time. Marc has correctly pointed out the fallacy in that presumption. It is very possible that nearly everybody in the motel will be running their coffee pots, TVs, and irons around the same time.

That also has an impact on the service and on the feeders to separate sub-panels (if there are any). What this really brings out is the fact that the NEC is not a design manual, and that its minimum requirements are not guaranteed to make the owner or user happy. In many cases, and I think this is one of them, you have to do more than NEC minimums, in order to have a satisfied customer.
 
Re: Loading a 20 amp circuit breaker

We have done some moderately sized Hotels 5 or 6 floors etc and the services have been fairly large 3000 to 4000 amps 208Y/120. The HVAC is a big part of that. The majority of the heating is often electric.
 
Re: Loading a 20 amp circuit breaker

Answering Questions Posed:
Question 1: The buck stops with me. I make the final decision.

Question 2: We have a recommendation to add another dedicated circuit, which unfortunately would require a new subpanel, since the existing subpanel is full and I don't know if the money is avialable at this time for that. That would make three dedicated circuits (I would probably put the microwave on it's own dedicated circuit with it's use frequency, but note that the hair dryer uses almost as much watts at the microwave).

Note that I neglected to mention the computer (500 Watts) I recently discovered and the radio-sterio (120 Watts) which would be in the motel room. Also recall I am converting two rooms in to one. It is only the receptacle breakers I am concerned with since the appliances plug in to them.

I really don't like to load my 20 amp breakers past 80%, so I will use 3 dedicated 20 amp breakers. There are many scenarios with high probability in my opnion here that would load my two 20 amp receptacle only breakers at max or exceeding.
 
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