New shop building. 3 phase or single phase option?

[Shop43]

Hi,
Currently we power a 15+1.5+1 hp grinder. Our current place has 3phase And we use a 45 kva to 480 step up transformer. Startup draws 16 and idle goes down To single digit.
Our new shop, electric co wants to charge 50k for 3 phase power so weighing out expense instead 200 amp service single phase 120-240 service with a rotary phase converter option.
Electric co says these power draws will destroy residential neighborhood transformers. This does not seem accurate given that a a North American Phase converter PL-40 needs 100a breaker (Already talked to NorthAmerican and they said no problem)
What would you do?

thanks in advance!!

 

[Philabuster]

Are you locked into a new contract? I would look for a different place with 3 phase juice.

 

[Shop43]

Yes have to complete single or 3 phase.

 

[jaguar36]

Depends on alot of things like how long you plan on being there, how big a shop it is, what your long term plans are and so on. I'd spring for the 3 Phase though as then you won't ever have to worry about it again. when you want a new machine or to upgrade or whatever. $50k does seem ludicrous though, are they having to run a new line from miles away or something?

 

[Fal Grunt]

I'm no electrician, but your using a 45kva transformer for a 17.5 hp machine?

 

[Shop43]

Retiring in about 10yr. Shop is 1300sq ft. 275’ of 3phase wire trenching, transformer eats most of the 50k

 

[EmGo]

Our new shop, electric co wants to charge 50k for 3 phase power so weighing out expense instead 200 amp service single phase 120-240 service with a rotary phase converter option.

Where in California ? A friend got them to bring in 3 phase pretty cheap by bringing in a bunch of sheep to the back yard and calling himself a farmer. Maybe he parked a tractor out front, too. He needed three phase for the well.

As soon as the power was in the sheep and tractor left. Farmers in Santa Rosa got special privileges. Don't know where you are but maybe a cow or two visiting could do magic ?

I think he did the trenching himself, but that's not such a big deal. Like you said, the xformer (and wire now) are the main costs.

 

[Fal Grunt]

Is it one single machine or 3 machines?

I wouldn't pay $50k for 3 phase. When I built my shop they quoted me something like $28k-$36k. I just laughed at the guy.

If your machines are all 480 and you can't or don't want to change the taps, get a rotary in 480.

 

[Shop43]

Is it one single machine or 3 machines?

I wouldn't pay $50k for 3 phase. When I built my shop they quoted me something like $28k-$36k. I just laughed at the guy.

If your machines are all 480 and you can't or don't want to change the taps, get a rotary in 480.

Have couple machines but only run 1 at a time.

 

[Fal Grunt]

Get a rotary. Or a phase perfect.

 

[Shop43]

And this range hp sizes should be ok on any new residential transformers? Or are these numbers hitting somekind of limit on a typical transformer (mostly morning powering on which is the spike)

 

[Fal Grunt]

I don’t know, ive got a 10 hp rotary that runs on my 200 amp service and the engineer from the power company didn’t think that would be a problem. My house and two other houses are on the same transformer as my shop.

My friend and I just installed a 30hp in his shop, the lineman from the power company said he could put anything in the shop that the 200 amp service would run.

Your situation/location/company will likely vary. I’d ask to have a lineman or local engineer come out to discuss it. Absolutely do not discuss it or listen to anyone on the phone in an office. They will 100% contradict what the person in the field says (my experience).

 

[Comatose]

400A single phase service is pretty common. What's the cost for that?

When I moved into my building, the power company had at some point in the past replaced one of the three 250KVA transformers on my pad with a 38KVA one. Probably fine for the previous owner, but it didn't last long with 5 ovens at 70KW each, 9 CNC machines, and all of that air conditioned. Don't intentionally screw around undersized, especially for a new build.

 

[mjr6550]

I looked at at requirements for residential single phase sevice for a couple utilities. One limits motors to 5 hp and the other 7.5 hp. The second one stated that the utility may allow higher hp.
The largest residential ac seems to be limited to 5 tons. I assume this is to limit high amperage draw. Backup electric resistance heat in heat pumps can be 20,000 to 25,000 watts, but they come on in 5000 watt stages.
Whether you can get away with a single phase service may come down to the maximum motor size or average draw when starting a machine. If you can get a larger motor running without exceeding the allowable limit you may get away with it because starting amperage is the main concern, not total amperage draw.

 

[Shop43]

I looked at at requirements for residential single phase sevice for a couple utilities. One limits motors to 5 hp and the other 7.5 hp. The second one stated that the utility may allow higher hp.
The largest residential ac seems to be limited to 5 tons. I assume this is to limit high amperage draw. Backup electric resistance heat in heat pumps can be 20,000 to 25,000 watts, but they come on in 5000 watt stages.
Whether you can get away with a single phase service may come down to the maximum motor size or average draw when starting a machine. If you can get a larger motor running without exceeding the allowable limit you may get away with it because starting amperage is the main concern, not total amperage draw.

So if any motor over +7.5hp has to be on 3 phase- It can’t be single phase with a phase converter. Then all phase converters in CA would be illegal In residential settings?

 

[stephen thomas]

Retiring in about 10yr. Shop is 1300sq ft. 275’ of 3phase wire trenching, transformer eats most of the 50k

Are they basically trying to force you into a demand meter?
Don't think that is what you want if you are setting up a play shop for retirement.
One max draw incident and that is the amount you will pay every month for 12 months, even if you turn everything off and never enter the shop again during that period.

I put in a phase convertor for that reason, in my (then) commercial wood shop even though 3ph is available next door from the old milking pipeline..
Took 125A from the house panel underground and left the legacy 30A overhead line up for lights.

I've told the story multiple times - blew the pole pig off the pole across the street when i put in a 15HP timesavers (It was 30HP, but i swapped motors)
NYSEG came out, inspected the shop, and instrumented the shop and house for 30 days. Then the engineer returned to check the data and gave me a clean bill of health, complemented my set up, and admitted the problem was that when i changed the old 60A pull fuses to heavy up the house to 200A service, NYSEG never changed the transformer. It was on them, not me.

The reason i described all that is that the people selling your contract will tell you whatever they want to optimize their income.
The excuses about why something won't work base on a given A x V are just that, excuses. You have to figure out from basic principles what will work for your situation.

With a couple surplus transformers, my system runs quite an assortment of machines including 220, 440 and even one 550/3 x 5HP motors.

Good luck but don't let them get you on demand meter in retirement.
You'll end up getting a generator as your work winds down to get away from them unless electric is really cheap in your area.

One thing i did was install an actual 3ph load center after the convertor.
It makes for a lot of convenience, arguably safety, and you can run branch circuits off of it instead of multiple extension cords.

smt

 

[ncjeeper]

I put a 400 amp service in my shop and have a 30hp rotary phase convertor. 3 phase is not close and the power company said it would be a little of 100k to run 3 phase to my shop. I said thanks but no thanks.

 

[Kallam]

20HP 230V → 460V Digital Phase Converter - Phase Perfect® Enterprise

www.phaseperfect.com

 

[ducesrwld]

there are always ways to get creative when i was looking at starting up in the ole garage i was going to turn my place into a multi unit home and get a 2nd 200 AMP service added to the property then after mr electric co stubbed it in it was going to get redirected straight to the garage.

there are some guys running some pretty serious garage / pole barn shops running some pretty good juice. what you are describing above is very doable. now if you are in CA who the flip knows that state wants to ram it so far up everyone's ass i'd think twice about trying skirt between the lines.

 

[Stirling]

Hi,
Currently we power a 15+1.5+1 hp grinder. Our current place has 3phase And we use a 45 kva to 480 step up transformer. Startup draws 16 and idle goes down To single digit.
Our new shop, electric co wants to charge 50k for 3 phase power so weighing out expense instead 200 amp service single phase 120-240 service with a rotary phase converter option.
Electric co says these power draws will destroy residential neighborhood transformers. This does not seem accurate given that a a North American Phase converter PL-40 needs 100a breaker (Already talked to NorthAmerican and they said no problem)
What would you do?

thanks in advance!!

Boy 1 machine at a time? Grab a phase perfect and call it a day.
I got 100a 240v. Running into my pp.
Runs a haas vf2 20”hp” and a import 20hp slant bed.
I can run 1 full tilt or both at 70% and never popped a breaker.
I think the breaker is even a 60or80a that it’s wired into.
Keep your runs as short as possible and upgrade the wire to let it flow well.

Who owns the “residential transformer” they are worried about?
I do t own mine and if it pops the power co. Can deal.
Maybe that will incentivize then to “help” you install a bigger line or 3p ??