need clarity on panel load

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fbendr

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hello, I have a multi panel service bank consisting 4 panels residential, 1st fl, 2nd fl, basement, owner. the 2nd floor panel main has a 50 Amp main breaker. with 5- 15 amp 120v loads. owner is renovating the floor and needs to add 2 20amp kitchen circuits and 1 20amp bath circuit. there are NO 240 V circuits in panel . can the load be calculated at 50 amps per phase? also was thinking of adding 20 amp/120v AC lines. trying to avoid increasing the main on panel.( but I know it should be done). not sure yet what main service feeder is rated at.

Thank You.
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Yet a 50A 120/240 or 120/208 main gives you 50A to work with on each line.

50A ? 240V = 12kVA.

12kVA ? 120V = 100A.
 
fbendr said:
Thank You my thoughts exactly. as long as everything is 120v. if anyone else disagrees please explain
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Keep in mind you still cannot exceed 50A calculated load on either line.

To do it right, you need to determine the ampacity of the feeder conductors. Could be as low as 46A and still be compliant. If less than 50A, that would be your limit.

And to do it completely right, you'd have to evaluate the entire service.
 
When you are doing load calculations, NEC is generally after finding VA and applying applicable adjustment factors to the VA.

You then divide by voltage to get amps. Whether you have a 120/240 feeder, 120 only feeder, or 120/208 feeder, find VA first then divide by voltage to get amps. Remember to balance this added load across all ungrounded conductors, or add any unbalance to what is there to get total amps needed for the new feeder calculation.

Adding two fixed 10 amp 120 volt loads is 20 amps added if both on same ungrounded conductor, but is only 10 amps added if balanced across both ungrounded conductors and the neutral
 
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