Industrial users are encouraged to balance the current on each of the three phases.
No problem with a proper 3 phase load but lighting is usually single phase to bays of lighting would normally be wired to different phases in the same way as houses down the street are wired to each phase in turn.
When you next have a power cut, sometime you will see 1 house in three along a road with no lights due to 1 phase having failed.
Industrial users are also encouraged to correct their power factor to near unity by having leccy meters that measure the product of voltage and current - so called VA meters. Domestic meter measure Watts which it he useful power your extract from the mains.
The leccy generators have to generate the volts and the peak amps so they generate VA and householder pay for Watts. The cost of so called Wattless power - the difference - is lost to them which is why they want the industrial users to correct their PF to near 1.
I have done some measurements on my belt sander. About the only machine I can load up to maximum with one hand and take meter photos with the other - safely (ish!)
OK firstly off load readings
VA the power they have to generate and your wiring/switches etc must withstand
Power that you are paying for
Applying a near maximum load to the sander with a block of wood
We get no change in the voltage
but the current is
The VA is
The power you pay for
and the power factor
Hope this gives some idea of what to expect
The idle running cost is less than a third of the full load running cost. I'd expect nearer 4:1
Now this a bit of a bodge experiment as my belt sander is a 3 phase and I only have a single phase power meter so the sander was jury rigged to a static phase converter (not 100% efficient!) so I could measure single phase power parameters to show you.
Hope this helps a bit more
PS I've left this on the end of the original thread as fixing the control box comments had possibly been made now and it gives some context with the machine.