bigsquarehead
New member
I have a client (equipment manufacturer) who, if you can believe it, is sizing MCC's for a fairly large greenfield manufacturing facility for which he is supplying the equipment.
He's sent me his motor list with his MCC assignments, and they are all overloaded according to my calculations. He tells me that all the motors are going to run continuously (at least for the length of one shift) so I calculated the connected load thusly: ((sum of connected loads)+(25% of largest motor))*1.25. My boss thinks that there's an exception for multiplying the connected load plus 25% of largest motor by 1.25 if the connected load is more than 800 amps. I've never heard that, but nonetheless am tasked with researching it. I can't find it in NEC 240 or 430. Is it possible? Are there any alternatives to the method I've used? The equipment is not loaded continuously, but the motors run continuously. Thanks for any and all help you can give me. -st
He's sent me his motor list with his MCC assignments, and they are all overloaded according to my calculations. He tells me that all the motors are going to run continuously (at least for the length of one shift) so I calculated the connected load thusly: ((sum of connected loads)+(25% of largest motor))*1.25. My boss thinks that there's an exception for multiplying the connected load plus 25% of largest motor by 1.25 if the connected load is more than 800 amps. I've never heard that, but nonetheless am tasked with researching it. I can't find it in NEC 240 or 430. Is it possible? Are there any alternatives to the method I've used? The equipment is not loaded continuously, but the motors run continuously. Thanks for any and all help you can give me. -st