Commercial kitchen equipment feeder calc's

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jbrown

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Hi gang,

I have a potential project that seems to skirt the edges for standard feeder calculations. What I'm finding keeps referring me back to branch circuits, which is not my issue at the moment, and I'm wondering if someone would double check my thinking process on this. And yes, Connecticut still uses the '05 code.

Here's the fundamentals-
The project proposes a new separate 120/208Y 3Ph~4w equipment panel to supply the following equipment:

5) Taylor 794 twin soft-serve ice cream machines. ( 2) 3P ckts/machine; 19.0 MCA ckt-1; 15.0 MCA ckt-2 per spec cut sheet, or 34.0A per phase)
4) Frigidaire FCRS201LF commercial refrigerators. (6.6A@120V/unit per call to Frigidaire, no tech info available online)
1) Turbo Air MUR-48 undercounter refrigerator. (6.5A@120V/unit per spec cut sheet)

Here's how I've been working to size the panel feeder and panel. Does this make sense or am I missing something obvious...?

1. Largest units are the Taylors. I'm using the Min Ckt Amps as permitted in 440.35 and the 1st unit at 125% per 430.24.
34.0A x 1.25 = 42.5A for 1st unit

2. I then added the remaining 4 identical Taylors.
34.0A x 4 units = 136.0A

3. I totaled the Taylors,
42.5 + 136.0 = 178.5A

4. As long as these Taylors are not HVAC units, I believe 220.56 lets me apply a demand factor, 70% for 5 units.
178.5A x .70 = 124.95A

5. I added two Frigidaire's each on the A & B phases, the Turbo Air was added to the C phase. I didn't apply any demand factors to the fridge's because, well really, its a minor load.
124.95A + 6.6A + 6.6A = 138.15A Total Load

I believe I should be able to use a 150A (min), 200A (preferred) feeder for this panel.

Anybody have any thoughts, yea or nae on my feeder calc's? Any input would be appreciated.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I see 220.56 as allow 65% for 6 or more kitchen units. Since you have 10 units I would use the 65% for all. Nowhere in this section does it say to take 125% of the largest so....

5-- 3p units at 34 amps per phase is 170amps on each phase
Now you have 5 units @6.6 amps but only at 120 V.( I rounded the 6.5 unit to 6.6 for simplicity). Thus we would only have 6.6 amps twice on phases A and B.
A phase- 170 amps + 6.6 + 6.6
B Phase 170 amps + 6.6 + 6.6
C phase- 170 amps +6.6

So the largest phase is 183.2 amps.
183.2 * .65 (65%) = 119.08 amps

Leave room for expansion and 150 amps is fine.
 

jbrown

Member
Thank you Dennis for your input and perspective.

As a follow up, I selected 5 units (70%) as the derating factor for the Taylors because as typical in the code, derating usually applies to like items like ranges, dryers, even apartments in service calculations. I took it subconsciously that that logic continued here. It didn't register that, with certain limitations, the factor applies to all pieces of equipment. This is also why I didn't bother factoring in any of the fridges either, their impact was minimal. Thank you for switching my desk light from the 50w setting to the 150watt level. I learned something new today.

My thought process for the 125% loading for one of the Taylors was that the machines are basically, a bunch of motors for refrigeration, mixing and cooling, each machine being properly circuit calc'd by the factory. Under ideal conditions, branch circuit design for multiple motors is derived by figuring 125% of the largest motor and the summation of the rest of the motors. Obviously incorrectly, I took the Taylor machine loads as the equivalent of multiple motor loads on a single branch circuit, considering that branch circuit as the actual feeder circuit would require the same constraints. This logic also apparently fell into that grey area outside my desk lamp.

Thanks again for a fresh look and any other comments are appreciated.
 
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