Determine Electric service size for work shop

[TMGT]

Unless there is a huge cost increase I would go with the largest service you can, the new shop I'm building at the house is getting 400a 208v 3phase, do I need that much at the moment?
Not really, but who knows what might be down the line and it's usually a lot cheaper to do it bigger the first time.

The killer for me is the cost of conduit and transformer pad, almost 3k in materials for the 240ft run underground.

 

[crazyal]

I think the first question is how many people will be working in this shop at once? Then the next question is are you running the power directly from the grid or is it going to be from the main panel in your house? My shop has 100 amp service simply because i ran it from my main panel in my house (200 amp service). It was a lot cheaper than running a 200 amp service from the pole. That would of required a new transformer, much heavier wire, and most importantly a separate meter and bill. That separate meter was an extra $20 a month even if I didn't use any power. For a shop with 3 guys working it wouldn't been a big deal but for just me 99% of the time 100 amps is way more power than I'll every use. I looked at getting 300 amp service for the house and the jump was very noticeable. But it really comes down to how many people are going to be working in your shop.

Yes my welder can draw 50 amps but I rarely ever use it at more than half power. The air compressor might spike the power when it turns on but when it's running it's not that high. The same is true for all of my equipment.

 

[buickanddeere]

200amp cost is little more than 100amp. Less of the annoying light dimming when Motors start etc with the larger wires

 

[TMGT]

200amp cost is little more than 100amp. Less of the annoying light dimming when Motors start etc with the larger wires

Exactly, I have 2 5hp compressors that cycle, I also will hopefully have my cnc mill and maybe a plasma in the future, all can be running at the same time and a compressor start while the cnc are running can cause major problems if the voltage drop is high enough.

Even with the manual machines it's nice to not worry about the a/c and compressors kicking on at the same time while welding.

 

[David_Kb7uns]

200AMPS is fine for most shops unless, you are growing things then you need lots more.

David

 

[Oldpath05]

"(40' x 120' is the shop size of my dreams...)"<<<<<<<<<<I concur with that statement. My shop 26'x36' has 200 amp service + it runs the house to. The shop has it's basic power tools, welder, drill press, air..............

 

[blakester]

Something else to consider. A 200 Amp welder doesn't roll 200 AMP's off the electrical system. I run an old miller 300 of a 30 amp breaker no problem all the time.

 

[flingwing1969]

Something else to consider. A 200 Amp welder doesn't roll 200 AMP's off the electrical system. I run an old miller 300 of a 30 amp breaker no problem all the time.

What Blakester said. I ran my Hobart 210 for a decade on a 30 amp 220 circuit and NEVER popped the breaker. They recommend a 40 amp breaker but I think that was overkill for sure.

 

[rodnok]

Thirty six years - 200 amp service to the out buildings has NEVER let me down. And it doesn't cost any more that 100 amp service.

WRONG! The panels costs more, the wire costs more. The pipe to run the feeder wires in costs more. The labor costs more unless you do it yourself. As for the electric bill, the amount of electricity you actually use is what determines that bill. The upside to the 200 amp service is that you have the ability to add machinery in the future.

 

[Ortimber]

Another vote here for 200A. That's a lot of power and I know I have never had a single issue in regards to not having enough power in my home shop.

My business (machine shop) runs on a 600A 230V 3PH service. I have a 15,000 ft/2 facility with office space, climate control, lighting, and 16 CNC machines running, sometimes all at the same time. Our average daily power usage is under 400A.