3 phase junction
Yes you could make up a portable breaker box (subpanel) with breakers rated within the maximum circuit rating for each air compressor, and with 15 or 20 amp breakers for the 120 volt stuff. If a piece of equipment normally draws 20 amps but is spec'ed for a 30 amp circuit, you may not connect it, or two of them, directly to a 60 amp circuit.
Now you cannot have 120 (110) volt circuits or subcircuits unless the 3 phase supply has a neutral specifically for 120 volt usage. This neutral might be symmetric (120/208 volt wye system) in which case any hot can be used wih the neutral, or may be associated with two of the three hot legs (120/240 volt delta system).
And the system must match the compressors' voltage ratings in terms of 240 versus 208 volts. Some 3 phase equipment will work on either 240 or 208 volts and the instructions or name plate will state that.
You may find it handy to have some adapters (receptacle to fit your portable breaker box, plug of lesser amperes rating) for use at different venues which might not have the same amperage circuit to give you. The box itself, its feed cable (wire gauge), and the plug at its end must all be rated for the maximum amperage circuit you will encounter in your travels.
You may not construct, possess, or use an adapter or Y connector with two male plugs on it. Such might be used to get a single allotment of 60 amps from two receptacles on separate 30 amp circuits, which usage is not allowed.
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Last edited by AllanJ; 01-09-2013 at 05:39 PM.