NEC 430.24 for packaged units

[crunchercrunch]

The code says that the conductors must be sized with ampacity not less than the sum of 125% of the FLA rating of the highest rated motor and 100% of every other motor.

Let's say I have a packaged unit with (6) motors of identical sizes at each 15HP. This unit has a nameplate FLA.

Do I calculate the conductor with the nameplate FLA and 25% of that whole unit, or do I calculate the nameplate FLA with 25% extra of ONE single 15HP motor?

If possible can you provide code references?

 

[infinity]

IMO if the package unit doesn't have a specific MCA and MaxOCPD specified then you calculate according to 125% of the largest motor + 100% of all of the others.

 

[crunchercrunch]

IMO if the package unit doesn't have a specific MCA and MaxOCPD specified then you calculate according to 125% of the largest motor + 100% of all of the others.

Got it. They do not have those numbers yet, as the manufacturer is still designing it. We are trying to provide a ROM for pricing and don't want to be out of the hunt due to incorrectly oversizing this feed. Thanks for the input.

 

[augie47]

409.110 might be of interest to you.

 

[crunchercrunch]

409.110 might be of interest to you.

I looked it up and while it does provide the FLA, I am ultimately looking for MCA. I was also unsure if the MCA is 25% of the total unit or just the single motor, bu thankfully it was clarified above. Also, I am trying to figure this out because we do not have nameplate information at the moment. I am trying to properly size the feeder for this packaged unit.

 

[augie47]

If you know all the loads, Infinity's post should suffice.