I bid wiring a large 3-phase printing machine that has a name plate value of 18kw at 240 volts, and the building voltage is 208. No PF on nameplate. (I asked the owner to confirm with the manufacturer that it would function properly on 208, and they came back to me with the answer "they said they think so". As much as I hate the word "think" in a sentence like that I'm being told to wire it sans transformer. Personally I would think the output of heaters would be pretty closely calibrated for 240 volts but that's not the question.)
My question is figuring proper circuit size.
The majority of the load is likely 1-phase UV heaters, but there are also multiple motors driving very large rollers. I figured a 60-amp circuit because there's no way to for me to figure amps at 208 without dissecting this machine. I'm afraid I lost this bid to a contractor bidding a 50-amp circuit.
What's the proper way to size this circuit?
My question is figuring proper circuit size.
The majority of the load is likely 1-phase UV heaters, but there are also multiple motors driving very large rollers. I figured a 60-amp circuit because there's no way to for me to figure amps at 208 without dissecting this machine. I'm afraid I lost this bid to a contractor bidding a 50-amp circuit.
What's the proper way to size this circuit?
