Feeder Calculation Debate

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brother

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Just want to get some other opinions on a calculation. This is commercial not residential.
I claim that the feeder is too small for the load. It's presently on a 2 pole 30 amp breaker, #10 copper wire that feeds a subpanel.
There's this 'espresso' stand, very small, and I did a calculation that used the 'kitchen equipment' demand factors NEC 2008 220.56. I consider the 'espresso' machine and the 2 coffee grinders kitchen equipment, and someone else does not.

This is a 120/208 feeder 2 hots 1 neutral 1 ground, single phase (of a 3 phase system)
here's my numbers all name plate ratings


espresso machine 208volts (Kitchen equipment) 5200 watts/va
2 coffee grinders (kitchen equipment) 7.5amps at 120volts 900va X 2 = 1800va
refrigerator 4 amps at 120volts 480 va
2 duplex receptacles 180 va each yoke 360 va


Kitchen equipment 90% demand factor 3 units 5200+1800=7000 X .90= 6300va
recptacles 100% 360va
frig 100% 480va
Total 7140
7140/208=34.32amps need a 40 amp feeder #8 wire 2 pole 40amp breaker to feed subpanel 4 wire.

So what do you think?? am I correct in this for considering the espresso and coffee grinders kitchen equipment? What else would you call it??
 
It doesn't have to be in a kitchen to be kitchen equipment.

I think that the refrigerator is the fourth unit with intermittent use or thermostatic control, thus allowing an 80% demand factor.

Then 5200+900+900+480=7480 x .8= 5984 va
5984+180+180=6344 va
6344 / 208 = 30.5

So the feeder is still too small for that list, close though.
 
Volta said:
It doesn't have to be in a kitchen to be kitchen equipment.

I think that the refrigerator is the fourth unit with intermittent use or thermostatic control, thus allowing an 80% demand factor.

Then 5200+900+900+480=7480 x .8= 5984 va
5984+180+180=6344 va
6344 / 208 = 30.5

So the feeder is still too small for that list, close though.
Click to expand...

so the refrigerator is considered as kitchen equipment?? never really looked at it that way.

That last part in 220.56 says However in no case shall a feeder or service calculated load be less than the sum of the largest 2 kitchen equipment loads
5200+900=6100va
or 25amps +7.5amps=32.5amps

Oh I just remembered there's a single receptacle I missed so that another 180va. There were actually 4 duplex receptacles, i didnt count them originally because the 2 grinders and 1 frig were going to be plugged into 3 receptacles of them. but that still leaves the single one that's not plugin into, so another 180 va. Am I thinking correctly on this??
 
brother said:
Its not exactly in a 'kitchen', per se, do make/mix drinks like mocha's , hot coffee. Well, I guess in our area according to our state amendments it would be a kitchen.

Be nice if you checked the calculation though.
Click to expand...
Why not include the fridge as kitchen equipment?

Are any of the other units hard-wired, or are they plug-and-cord connected and to dedicated or GP recept's? The point I'm trying to make here is that the equipment can be considered as kitchen equipment ... but can also be considered not kitchen equipment, where some or all are just using GP recept's and a calc of 30A or under could be made. So it all depends on one's train of thought when doing the calc.
 
Smart $ said:
Why not include the fridge as kitchen equipment?

Are any of the other units hard-wired, or are they plug-and-cord connected and to dedicated or GP recept's? The point I'm trying to make here is that the equipment can be considered as kitchen equipment ... but can also be considered not kitchen equipment, where some or all are just using GP recept's and a calc of 30A or under could be made. So it all depends on one's train of thought when doing the calc.
Click to expand...

They are plug and cord connected, but these units are not easily moved. Its not like they unplug and replug it again so its more like 'dedicated' receptacles. Since they are specifically for the espresso, thats one of the reasons I dont just use the gp receptacle calc. The load is known.
 
Last edited:
I was reading 220.56 again, NEC 2008, the last paragraph, however, in no case shall the feeder or service calculated, load be less than the sum of the largest two kitchen equipment loads.

I can interpet this 2 ways on the 'calculated'. Would you add the actual amperage of the loads or would you add Volt Amps and divide by voltage.

In this case, I had the 25 amp expresso and the 7.5 amp coffee grinder. 25+7.5=32.5amps
But, if you do the the VA way 5200+900=6100/208=29.32

So when they say the sum of the largest loads, which would a person use? I would use the 32.5amps in my opinion.
 
brother said:
...In this case, I had the 25 amp expresso and the 7.5 amp coffee grinder. 25+7.5=32.5amps
But, if you do the the VA way 5200+900=6100/208=29.32

So when they say the sum of the largest loads, which would a person use? I would use the 32.5amps in my opinion.
Click to expand...

The draw on one leg will be 32.5 amps, the other 25 (for these two loads). You have calculated it thus. Your opinion matters! :grin:
 
brother said:
...
I claim that the feeder is too small for the load. It's presently on a 2 pole 30 amp breaker, #10 copper wire that feeds a subpanel.
...
Click to expand...

brother said:
They are plug and cord connected, but these units are not easily moved. Its not like they unplug and replug it again so its more like 'dedicated' receptacles. Since they are specifically for the espresso, thats one of the reasons I dont just use the gp receptacle calc. The load is known.
Click to expand...
I wasn't contesting your premise for the calculation nor changing the feeder as a result, but rather providing an explanation why it may be how you said in the OP. The NEC is about determining minimums, and some take it to the extreme, or perhaps they didn't know the load at the time. Even going about it as you are calculating is in effect a minimum. Subject to equipment rating constraints, you could size the feeder even larger than your calculations warrant.
 
brother said:
...espresso machine 208volts (Kitchen equipment) 5200 watts/va...
Click to expand...

Is this the nameplate rating at 208 Volts? Or is this machine dual-rated (240-208)?

IF the 5200 watts is a 240 Volt rating, then it will only supply 3900 watts operating at 208 Volts. 18.75 Amps if this is the case. :D
 
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