Bill
Ten years ago I moved to a new place and had the pleasant opportunity to have a new building for my shop.Of the many Items of importance the electrical was high on the list.I have eight 3ph machines.They are driven by either a VFD or Rotary converter.The largest is a 7.5HP air compressor.I put in 100A 220v from the house to building.From the shop building main I had two sub panels, one for all the 3ph equipment and one on the far side of the building so I could reduce wire run lengths.Building is 60 feet long and has four rooms built in it.Since I was not sure I would always use a rotary or a VFD for a particular machine I set up a distribution panel off of the 3ph sub panel.For each machine I have a disconnect box.The disconnect box has fuses which are custom fused for the size of the motor being fed not the size of the wire going to the moto. The point is I want the motor protected and the wire is always way larger than the motor draw.Use special slow blow fuses.From the distribution panel to each disconnect box I ran #10 wire (to minimize voltage drop) for 3ph 220v ie 3 wires.I also ran #12 wire for a single phase 220V ie 2 wires.In addition I ran a neutral associated with the 220V so I could create 110V if needed.Of course there was a ground wire run for each ie 2 ground wires.Basically the rotary was fed from the 3Ph panel and its fused output went into the distribution panel to feed all the 3ph.The distribution panel had several power relays in a configuration that if for any reason there was a power hit the panel would drop out all the feeds (every wire including the neutral) to the disconnect boxes.The only way power could be restored was with a manual reset.This was primarily for safety so I would not have a machine just start right back up when the power came on.I could clear the cut or whatever and hope for the least amount of damage. The power relays were tied to the light circuit so when I turned off the lights at the end of the day all power was dropped.That is the basics.At each machine I have available any power combination I want.I can take just the 220V and hook up a VFD or run the 3ph directly.If I have other attachments on the machine ie lights, power feed etc I have 110v.Adds to the cost but I will tell you ten years later when I needed to change how some machines were run it made it real simple.I suspect you might ask, I have a friend who was an industrial electrician.He laid our power for factories.He worked with me to make sure everything was up to code.
It was mentioned earlier make sure you account for stuff always running ie lights, mine pull 18A if all on so I have several extra switches so I can turn on what I need.The refrig, microwave, fans (I have ceiling ones cuts heating bill with ten foot ceilings), and any other little thing, they all add up.My guess is your plan for 100A should be just fine.I actually did a test and turned every tool, light etc on for about ten minutes and during that time kicked the air compressor on.No light diming and the input from the house was pulling 94A with the air compressor running.The air compressor uses a VFD with 6 sec ramp so I really did not expect a problem.I was satisfied that all was working well.
Bob
