Branch circuit load calculation kitchen equipment

[kwired]

But that's just it, the whole circuit of receptacles is for general use... until reduced to one receptacle .

Code requires a minimum two 20A SABC's for dwellings calculated at 1500VA each for a reason, yet gives non-dwellings a bit of leeway. In my experience, a breakroom will at times, given the conveniences we take for granted in our homes, be put to simultaneous use the same if not more than in a home.

A maintenance shop I've worked in a couple times in as many years has 4 microwaves on the same circuit (and of all places, a 2.4MW power plant ). There is shall we say no scheduled lunch time, but it never fails that during shutdowns when the staff has been augmented, at some point all 4 microwaves will be put to use, and you can guess the rest... :angel:

I'll guess, they draw so much power the generation plant ends up going off line so it can supply support operations, which is the break room at this point.

My point here is I have seen many break rooms for small offices, shops, etc. that have limited branch circuits feeding these small appliances and most of the time they have little trouble overloading circuits. If there is multiple microwaves, they are likely there because they do get used simultaneously. If there is one microwave, one toaster, and other single appliances in a room with a small number of users, they may not get used at same time very often if ever. Coffee makers are usually drawing more significant load when brewing than when warming.

 

[brother]

I'll guess, they draw so much power the generation plant ends up going off line so it can supply support operations, which is the break room at this point.

My point here is I have seen many break rooms for small offices, shops, etc. that have limited branch circuits feeding these small appliances and most of the time they have little trouble overloading circuits. If there is multiple microwaves, they are likely there because they do get used simultaneously. If there is one microwave, one toaster, and other single appliances in a room with a small number of users, they may not get used at same time very often if ever. Coffee makers are usually drawing more significant load when brewing than when warming.

In this building, it is definitely more likely they will be used at the same time. In fact, I have always seen where additional appliances were added. Such as another toaster, baker oven, and another microwave. Dont ask me why they need all of that, but I have yet to see it not happen. This room apparently is accessible to both visitors and staff. In this particular instance, its definitely good common sense to add the other circuit, which is cheap.

 

[david luchini]

You did not quote code directly.

:? In post #22, I quoted...

Branch Circuit, General Purpose: A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.

This is a DIRECT QUOTE from Article 100 of the Code. I don't know how to be any more clear than that.

The NEC would have not added Appliance Branch circuit definition if every outlet or receptacle was a 'General Purpose'. Remember these outlets were intended specifically for these appliances so it would meet the definition of Appliance Branch Circuit definition to a tee!. If that was not the intended purpose you may have a basis of argument.

By your logic, there would be no such thing as a general purpose branch circuit. If you had a branch circuit in an office space with say 6 receptacles on it that was intended for plugging appliances such as computers and monitors (meeting the definition of general purpose branch circuit) it would cease to be a general purpose branch circuit as soon as an appliance is plugged in?!?! I don't believe that this is what the code intended.

I know this is an age old debate, on whether the NEC extends beyond the outlet or receptacle and affects the end user. I believe you are incorrect. The code does speak to the end user in many situations on what may or may not be plug into the receptacles. 2008 NEC 422.51 on vending machines come to mind, or 422.45 or 590 that deals with holiday lights. Another code section is 210.21(B)(2) Total Cord and Plug Connected Load.

I don't see that at all. 422.51 refers cord-and-plug connected vending machines requiring a GFCI as an integral part of the attachment plug. 422.45 refers to electrically heated appliances intended to be applied to combustible materials requiring a Stand. The only thing I see about "holiday lights" in Art. 590 is that they shall be "listed" and not used for more than 90 days. As far as 210.21(B)(2), it only tells you the maximum cord-and-plug connected load that can be connected to any single receptacle, but says nothing about the branch circuit as a whole.

Whether the end user knows the NEC or not, this does not change the fact that the NEC applies or has been violated on occassion.

You seem to be contradicting yourself here. Earlier, you stated that it was a Code violation to KNOWINGLY exceed the rating of a branch circuit by plugging in appliances with a sum of ratings that exceed the rating of the branch circuit. Now you are saying it is a violation if someone UNKNOWINGLY does the same.

You also misquoted 90.2 . Read it again, it is not just limited to premise wiring, it also says in (3) Installations of conductors and equipment that connect to the supply of electricity. No where will you find in the NEC where it says it will NOT apply to the end user or what may be plugged into receptacles.

I didn't QUOTE 90.2 at all, so I'm not sure how I could have MISQUOTED it. :? But 90.2(3) says Installations of conductors and equipment that connect to THE SUPPLY of electricity (ie, the source.) The appliances in question do not connect to THE SUPPLY of electricity, but rather to receptacles outlets on the premise wiring system. You will not find anywhere in the NEC where it says that it DOES apply to what the end user may plug into the receptacles, other the maximum cord-and-plug connected load for any single receptacle or single piece of equipment on a branch circuit per 210.21(B)(2) and 210.23(A)(1). But Article 210 is SILENT on the calculation of branch circuit loads. Article 220 covers branch circuit loads.

So when these outlets(receptacles) are intended for coffee pots and toasters that exceed the 20 amp branch circuit, the moment someone plug them in and turn them on and exceed the rating, it is a violation.

Again, this is not correct. 220.10 says branch circuit loads shall be calculated as shown in...220.14. 220.14(I) says that RECEPTACLE OUTLETS (which is what you have on your branch circuit) shall be calculated at not less than 180VA per single or multiple multiple receptacle on one yoke. You will find NOTHING in 220.14 about calculating the load on a branch circuit based on the ratings of the appliances plugged into the receptacle outlets. Zero. Nada. It's simply not there.

 

[kwired]

In this building, it is definitely more likely they will be used at the same time. In fact, I have always seen where additional appliances were added. Such as another toaster, baker oven, and another microwave. Dont ask me why they need all of that, but I have yet to see it not happen. This room apparently is accessible to both visitors and staff. In this particular instance, its definitely good common sense to add the other circuit, which is cheap.

Good common sense is right, that is design not code. If there are not enough circuits for the load, code still kicks in because of overcurrent protection. Code is for safeguarding of life and property not a design manual. The overcurrent protection accomplishes this safeguarding if there is not enough capacity to handle the load because of a design issue.

 

[iceworm]

I don't know about other states, but here the NEC only applies to new construction. The second the AHJ inspector walks out the door, the use is no longer a construction issue. The owner can plug in anything they want. There will not be a swat team of electrical inspector agents kicking in the door. The NEC just doesn't apply.

... This is commercial break room, not a dwelling unit.

Now the fire marshal cares, OSHA might even care. Either of those can enforce what gets cord and plug connected. The fact the NEC says plugging in two 16A microwaves into a 20A circuit is bad juju, is completely indifferent.

Now if it is residential - nobody cares. Plug away.

ice

 

[kwired]

I don't know about other states, but here the NEC only applies to new construction. The second the AHJ inspector walks out the door, the use is no longer a construction issue. The owner can plug in anything they want. There will not be a swat team of electrical inspector agents kicking in the door. The NEC just doesn't apply.


Now the fire marshal cares, OSHA might even care. Either of those can enforce what gets cord and plug connected. The fact the NEC says plugging in two 16A microwaves into a 20A circuit is bad juju, is completely indifferent.

Now if it is residential - nobody cares. Plug away.

ice

If the two 16 amp appliances are plugged into the permanent receptacle and not a portable plug strip, the fire marshal or OSHA inspector doesn't even look any more into this.