Er...what 3 phase power circuit to install?

[theboosh]

Hi, the company I work for needs to use some machinery in the US, it says it requires 208v 3 phase, I think it requires 32amps ( >40 max ). Should I specify that a 40A circuit is required? The building already has 3phase to it.
Also, does the three phase give me 3 'normal' circuits to play with (110v) to power an ancilliary device that hangs off the power supply? I also need to get an ELCB and another circuit breaker for the machine, but am not sure of the spec...can anyone help? ? ? ?!

 

[Senselessticker]

I recommend getting some help from a local electrical engineer or electrician. Also, You need to be "sure" of the current rating of the equipment. Other useful information about the load: is it a motor load? resistive heat load? etc...this helps determine cabling and breaker requirments.

To answer your question about 110V power to "play with": 208 is the line to line voltage and 120 will be the line to neutral voltage. Most 3 phase 208 V loads require no neutral connetion, so your stuck with 208. I would reccommend powering the auxillary equipment from a seperate circuit. In any case....I believe you need some help from someone with an electrical background.

Regards,

Sense

 

[EEJaime]

If the machine you mention indeed draws 32 Amps, then the 40 Amp, 3-phase, 3-wire circuit will be fully loaded and nothing else will be allowed by code to be fed from this circuit as breakers of this size are 80% rated. That is max allowed current is 0.8x40A=32A. You would need to bring additional circuits from your branch panel fed by single pole circuit breakers for your 120v. loads. If you used 3-1pole, 20A. c/b's, ran 1/2"conduit with 4 # 12awg conductors, with 1 # 12 ground. You would have three 120v. circuits to feed receptacles, ancillary devices,etc.... You should still be sure to get the exact load requirements of all equipment being served so that none of the circuits are overloaded, and of course you need to be sure that the upstream panels and service have the capacity to serve your new loads. A local electrician, whom I assume would be doing the installation, will be able to properly size and connect these circuits.