Two Questions on 220.55 & .56 - Commercial Kitchen Equipment

[paullmullen]

For reference, here is the text of 220.56 (NEC2017):

220.56 Kitchen Equipment — Other Than Dwelling Unit(s). It shall be permissible to calculate the load for commercial electric cooking equipment, dishwasher booster eaters, water heaters, and other kitchen equipment in accordance with Table 220.56. These demand factors shall be applied to all equipment that has either thermostatic control or intermittent use as kitchen equipment. These demand factors shall not apply to space-heating, ventilating, or air-conditioning equipment. However, in no case shall the feeder or service calculated load be less than the sum of the largest two kitchen equipment loads.

Two questions:

1) When calculating the load before the demand factor, do we just add up the demands on the rating plates of the equipment? I can imagine all sorts of more complex approaches including:
- Using T220.55 to calculate the loads.
- Doing load calculations for single phase appliances on three-phase 4-wire systems (Divide loads by 3 and then double)
- and more.

2) When using 220.55's reference to household appliances in instructional programs. What differentiates a household appliance from a commercial appliance?

 

[tortuga]

1) When calculating the load before the demand factor, do we just add up the demands on the rating plates of the equipment? I can imagine all sorts of more complex approaches including:
- Using T220.55 to calculate the loads.

I think they are mutually exclusive.
If your calculating the load for ranges in a instructional program, I would think that would be a school classroom type occupancy not usable as a commercial kitchen.
While you could have an instructional program in a commercial kitchen that also used for non instructional purposes, then its permitted as a commercial kitchen and you use 220.56 not 220.55

- Doing load calculations for single phase appliances on three-phase 4-wire systems (Divide loads by 3 and then double)

I do my three phase calcs like the example D3(a).
I'd add up all the nameplates in VA
Next apply the demand factor
then divide by the L-L voltage * SQRT(3) to get the line amps.
Like where they have the "Conversion to amperes using three significant figures" part.

This does presume a balanced panel, and if I need to get more involved I make a panel schedule spreadsheet in amps & VA for all the phases.
It also presumes you have a full delta or wye supply.

 

[paullmullen]

I think they are mutually exclusive.
If your calculating the load for ranges in a instructional program, I would think that would be a school classroom type occupancy not usable as a commercial kitchen.
While you could have an instructional program in a commercial kitchen that also used for non instructional purposes, then its permitted as a commercial kitchen and you use 220.56 not 220.55


I do my three phase calcs like the example D3(a).
I'd add up all the nameplates in VA
Next apply the demand factor
then divide by the L-L voltage * SQRT(3) to get the line amps.
Like where they have the "Conversion to amperes using three significant figures" part.

This does presume a balanced panel, and if I need to get more involved I make a panel schedule spreadsheet in amps & VA for all the phases.
It also presumes you have a full delta or wye supply.

Yeah. sorry, I kinda combined two different questions into a single post.
1) How to do the pre-demand-factor load calc
2) What defines a household appliance in a commercial setting.
Next time I'll do two different posts.

Regardless, for your response to the pre-demand-factor load calc makes sense. Basically, just do the math as you might for a Multi-family dwelling, working toward as balanced panel. Then apply the Demand Factors in 220.56.

Thanks for engaging.