I'm looking to feed 13, 208/230v 25 amp single phase air conditioners from an existing 200 amp 3 phase panel with almost no load. The a/c cut sheet states total input 2500w. 2500w divided by 208v is 12.0, why do they spec a 25 amp breaker? 2500w x 13 is 32500w divided by 208v is 156.25amps. Am I close, might this work?
cplinc
- Thread starter cplinc
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RUWIREDRITE
Senior Member
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- PA, Business' in NJ/PA
Total load
Total load
Whats the rest of the load to the 200 amp panel, seems like your in there minus the existing load.
Total load
Whats the rest of the load to the 200 amp panel, seems like your in there minus the existing load.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
They probably spec a 25 amp breaker so that the breaker will not trip during motor start. So long as the conductors are large enough to be able to be protected by a 25 amp breaker (i.e., at least 10 AWG), then you are OK.
You left out the factor of the square root of three.
32,500 divided by 208 and divided again by 1.732 gives you about 90 amps. You describe your existing load as being insignificant. I would say that if the existing load is less than 25 amps, you certainly have the room to add these air conditioners. But if the existing load is higher than that, I would not be able to say if you have the room, without going through a formal process of measuring the load for 30 days, or calculating the actual connected load.
You left out the factor of the square root of three.
32,500 divided by 208 and divided again by 1.732 gives you about 90 amps. You describe your existing load as being insignificant. I would say that if the existing load is less than 25 amps, you certainly have the room to add these air conditioners. But if the existing load is higher than that, I would not be able to say if you have the room, without going through a formal process of measuring the load for 30 days, or calculating the actual connected load.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
My guess is that the unit have a minimum circuit ampacity of around 15 amps. In that case you could wire them with #14 THHN and still protect the conductors with a 25 amp OCPD.
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