Bkessler

I will be installing a 200 amp rated main lug sub panel for a concession stand. The loads are coffee maker, bun warmer, ice machine , water heater, ect. The loads are: phase A- 72 amps B-68 amps and C- 65 amps. What would be the minimum wire size for this and what are the steps to formulate it. I would think it's something like 125% of 72 divided by 1.73? I am not sure but the panel is 90 feet away from source and ran in 1.25 emt.

thanks bk

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Greg

I based my calcs off 200A because you know it will be added to down the road. At 200A I came up with 250MCM because I'm assuming The majority of the loads are linear. I didn't derate because of that but I did a correction of .82 temperature, I calculated the VD (based on 208 3Ph.) at 100' and it was negligible. The only problem is you can not get 250's in the pipe.

But at 90A with a temp correction of .82 you could pull #1 CU. Based off the 60c column because it is less than 100A. But you should bump the EMT to 1.5 because the you can only put 4 #1's in 1.25 EMT and you need 5 conductors; 3ph's, a neutral, and a ground.

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Bkessler

Well I am not pulling 250's thats for sure, and it's one solid run of 1.25 emt so I do not need a ground wire either. I was hoping I could get away with at least #2's.

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waco

I'd say #2 or #1 copper, THW-2 should be more than adequate and I'm not too sure #3 THW-2 wouldn't be adequate.

wirebender

Why are you using a 200A panel for a 72A load? I'd use a 100A or 125A if I needed the spaces.

Water heater is continuous load at 125%
It's hard to figure the load on "ect."


How did you determine this? Does it include the 125% for the W.H.? Lights?
Is there gonna be any heat? 1500 watt space heaters add up in hurry.


Wire size is in Table 310.16.
once you know your actual load you just look it up in the proper column and derate if necessary.


Huh?


90 feet is not far enough to worry about VD.

You're welcome