Hey Gang,
Hope everybody's well. Here's my latest question on the quest to build the perfect workshop:
What kind of amperage do I need?
I'm not going to be able to get a 3-phase line in, so I'm looking at running everything on straight 220, or possibly getting myself a phase converter for a couple of items.
Anyway, does anybody out there have any useful specs on the electrical system at their own workshop? I'm not an electrician by any means, so I'm just trying to figure this stuff out from the ground up--any information would be useful.
Thanks,
Zack
(PS. hopefully this post is in the right area...it was the closest match I could figure.)
Zack Jonas
Journeyman Smith
Zack,
I reccomend that you treat your shop as a commerecial environment.
The NEC covers commercial calculations in Art. 220. You must look at the definitions in Art. 100, be familiar with what Art. 210 says about continuous loads, and understand the overcurrent protection requirements set forth in Art. 240. Art. 220 doesn't cover all specific loads. For example, you'll find motors in Art. 430 and air conditioners in Art. 440.
Calculate each recepticle (strap) as 180 VA, in a home you can put up to 10 straps per 15 amp circuit. In commerecial use, no circuit in your shop should be less than 20 amps (NEC allows a 15A circuit but, local requirements may still be as the older NEC requirements of only 20A circuits in commercial installations).
120V x 20A = 2400VA load permitted
2400VA / 180VA = 13 recepticals (straps) permitted on a circuit, use this for general purpose circuits.
Motors should be rated at 125% of the rating for standard loads, heavy duty loaded motors (Power hammers, presses, etc) calculate at 150% for their startup values.
I am doing the load calculations for my new 10x16 shop in order to present them to the building department for permiting. I have ordered a pre-built shed structure to be placed in my back yard to act as my studio/shop for bladesmithing. I am doing the interior with 2 of my daughters help (they are both licensed general contractors and in a prior life I was a state licensed electrical contractor-Florida.)
I calculated 3 general circuits that include my lighting needs at 20A each, 5- 20A circuits for buffer,wood sander,6,000 BTU AC unit, wood band saw, and small drill press. 2- 30A circuits for a large drill press, and a 3hp VFD grinder; double pole (220) circuits I have 2- 20A, one for a 2hp VFD grinder, one spare; 2- 30A ones, small oven, large metal band saw. I am also piping in for 2- 220 lines for future power hammer and small press, 1 inch pipe with stove box to each.
My panel is a 200A 120/220 panel - 24 slots (circuits), which will have a 100A main breaker and the feeder wire for 150 Amps, if I need more amps in the future I will just need to change the breaaker and I am ready to fly.
If you need any help let me know, with a total list of equipment and the amp rating of each item I can do the calculations for you.
Edit: I use two VFD for 3 phase grinders on 120 volt and 220 volt circuits.
