• We will be performing upgrades on the forums and server over the weekend. The forums may be unavailable multiple times for up to an hour each. Thank you for your patience and understanding as we work to make the forums even better.

Multimotor and 120v OCP sizing

T

Tbatson44

Member
Location
Springfield, MO
I have a motor control cabinet fed 240VAC 3phase controlling 6 motors and then 1 - 120VAC (L1 to Neutral) load but I'm not seeing proper calculation for OCP. I am getting caught up with 430.53(B) and it saying this must be sized for the most severe normal conditions. Do I just size this to protect the conductors so 125% of the largest motor plus the sum of all the others? I have 3 - 15hp motors, and 3 - 10hp motors, then L1-N for my 120VAC load.
Thank you.
 
petersonra

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
There is a feeder conductor sizing rule you can use that allows you to have a smaller conductor than you might think based on the ocpd size that the feeder ocpd sizing rule would allow. You can use it or you can size the conductor to the ocpd rating. It is a design choice.
 
You must log in or register to reply here.
Top