Sizing of feeder and motor cable

I count 5 circuits, not 4, but that doesn't really matter.

Take the total connected load x 1.25 for sizing the main service and bus bars, more if you want future expansion capability.

Each individual circuit needs its own "feeder" sized according to whatever your local codes require. But typically, you can just look at what the equipment manufacturers recommend for those given motor sizes. As for the packaged water equipment, if you have a nameplate FLC use that, x 1.25. If not, calculate the FLC using I = kW/1.732 x E x pf (cos. phi) x 1000. If you don't know the Power Factor (cos phi), use .8 if it has motors or large inductive power supplies, 1.0 if not. Then use the feeder breaker closest to 1.25 x that FLC value.

You need the fault current analysis in order to tell the MCC manufacturer what they need to build the bus bar system and protective devices ratings to withstand. Not the other way around. So you need to look at the available source ampacity, transformer impedance, wire length, contributing loads etc. etc. etc. It's not something to be done on a napkin, it takes a qualified electrical engineer. Hire one if you have no idea what I just said.

That's right JRaef, he needs a professional consultation. This is an elaborate study. For motor feeder we need to calculate the starting voltage drop in the circuit and the voltage available at motor terminal. So as for Feeder considering all the cable from one feeder to end motor load or to keep the bus voltage maintained at the bus where the feeder is connected.

Take the 3-phase loads and work out their FLC (or running current if known) as suggested in earlier thread, add together and apply a factor of 1.3 for spare capacity for future load growth of the busbar. The 2kw single phase load is almost negligible.

Then determine the applicable rating, type and class of the protective device rating to be used as motor feeders bearing in mind the various starting methods of the electric motors ; soft start, direct-on- line or star- delta.

For the fault current checks, its much complicated as you'll need to get details of the upstream power supply parameters and configurations, etc., so contact a consultant.

Also the 450Volt rating of the packaged water equipment should not exceed the rating of the MCC.

Good luck.