new workshop build question on 3 phase wiring

[Greg Brophey]

hello to all,

I am planning on building a new workshop/garage/storage area next to my house which will be situated on the adjoining lot I own. My intentions are to sell my current residence and build new house on this adjoining lot which I did buy it for. No sense in building it on home lot. Now to the facts. This new building will be built with high degree of energy efficiency from the bottom to the top. I am not going to ask questions on that, but need to ask questions on electric supply to this. I would like to service it from my home box, which is currently a 200 amp service. I would like to install a 100 amp breaker box off this to feed the new workplace until I ever should get the new home built. The approx. distance to this workshop from existing service panel is about 200 ft.

My first question would be the distance? Is this too far to install a new panel in workshop which I plan to use? All my machinery, most anyways, is 3 phase. I have a 3 phase converter and believe it is 10 hp phase converter. I realize I cannot use all machines at one time but do know most can be used only at one time which is fine for now. How do I start this wiring design out? I read on some other posts here that what was recommended was a 3 phase panel or something like that. Is that correct? I really want to wire this right as my only upgrade some day may be the phase converter. I also am not sure, but in checking on the converter, it will run a 5 hp 3 phase max. My Oliver planer is 5 hp along with a few 5 hp tablesaws, so I should be properly sized for one machine running at least, or at least, I think. Please comment on what I should do on this wiring endeavor, as 3 phase to single phase by use of 10 hp phase converter is all new to me. I will also need regular 120 volt lines for lighting, and not sure what type of heat I am going to use. Please realize this will have to suffice until I get the other house built and it makes no sense to run a separate line to this workshop for anything any higher in service due to high cost. I have to make due to what I will be able to bring in and that is 100 amp service line as I understand it. My existing home line can be upgraded to 300 amp, and jump off that with 100 amp disconnect panel but I am not sure even about that or if the 300 amp upgrade is even necessary.

I plan to do this myself and have plenty of time to get the wiring figured out beforehand. I figure there is no sense in describing what 3 phase machinery I have since only one can be run at one time as I have been told. What has to be figured in is heat, and I am thinking of a small electric heat pump type system such as a mini split ductless heat pump. Any recommendations greatly appreciated as I live in OH where it gets both hot and cold, so air would also be nice.

Not sure of size but figure it has to be at least the size of a 3 or 4 car garage, which I may build it to, as it will give any new owner the option of using this as garage and not just a workshop. The insulation value will approach the highest level of value I can put in it with regards to cost and maximum return of electric savings. My cost for electric here in my local area is about 5.5 cents per kilowatt hour which is very low compared to other areas. No gas, no propane, but an option should I consider it.

Bottom line. How do I wire this for 3 phase woodworking machine use and what special service panels need to be installed and how. I would appreciate any and all suggestions on everything as I learn from others who have gone before me and make no bones about it- this I have never done before.

thanks in advance.

[Kevin Jenness]

I have a similar situation, with primary service at my shop building about 100 feet from my home and a phase converter for several machines.

First, get a qualified electrician involved. You can get some good advice here but you really want someone on the ground looking at your specific situation, preferably someone familiar with commercial wiring and controls. Any master electrician should be able to set up what you are describing but it can be very helpful to have someone who can suss out wiring diagrams, starters, vfd's and the like.

200 ft is not too far as long as you have the proper cable size. That depends on the load, and you will have to add up the maximum amperage demand for machinery, dust collection, light, heat and anything else. 100 amps will probably suffice for the shop, but you need to do the math to be sure.

For many years I had only a 100 amp service in the shop with a 100 amp breaker feeding the house. Minimal, but it worked. One disadvantage was that if I needed to cut shop power the house was off as well. When I enlarged (1080 sq ft) and rewired the shop the new meter box included a panel to allow disconnecting the shop and house independently. The distribution panel in the shop was upgraded to 200 amps. I have a 10 hp homebrew phase converter running off a 60 amp breaker which feeds a 3 phase subpanel. Each 3 phase machine is on its appropriately sized breaker in the subpanel. I also have a couple of 3 phase machines (exhaust fan and edge sander) running on single phase supplied variable frequency drives in order to have speed control.

Since you plan to build a new house on the same lot as the new shop, do you really want to power the shop from the existing residence? You may want to run a new service to the shop rather than wind up changing it around when you move.

Where do you live that has 5.5 cents/kwhr?

[John K Jordan]

Greg,

I can't address the 3-phase issues. But the distance is no problem.

I ran power 250 ft underground for my shop and installed a 100 amp panel. To size the wire I used an on-line calculator which takes into consideration the acceptable voltage drop. I think 3% is the generally acceptable drop. Figuring for the unlikely but possible full 100 amp load I calculated the wire size then installed a larger wire for less than 3% drop. It is copper and was not cheap but it wasn't much compared to the cost of the shop, everything in it, the time it took to build, and the expected length of time I'll use it. I have 5 hp motors on my DC and air compressor and see no light dimming or other signs of a voltage fluctuation when they kick on. I also run a heat pump for heat and air.

I dug the trench myself with my tractor/backhoe and installed 2" conduit. The cable I used was so thick that instead of laying the conduit and pulling the wires I stretched out the wire next to the trench and slide each piece of conduit into place for gluing. BTW, I put in an extra run of conduit empty except for a rope in case of a future need. I also ran a smaller conduit with ethernet cable.

JKJ

[Malcolm McLeod]

...
Since you plan to build a new house on the same lot as the new shop, do you really want to power the shop from the existing residence? You may want to run a new service to the shop rather than wind up changing it around when you move.
...

^+1
You didn't indicate whether your electrical service is overhead or buried, but I'd certainly look hard at feeding the new shop off a new service for the shop property. It would have its own meter, but your utility provider may be able to merge the bills for the shop and the existing house? When new house is built, you simply tap off the now existing meter to feed the house. ...And never touch the old property's service or the feed to the shop.

[John K Jordan]

...feeding the new shop off a new service for the shop property. It would have its own meter, but your utility provider may be able to merge the bills ...

I would also prefer a separate service - would give more flexibility for the future.

But the practicality may depend on the utility. My barn and associated building are 100' from the pole but 400' from my transformer and house service. I asked about a separate service and meter and they told me sure, but a second meter would be charged at higher commercial rates and there was a minimum usage charge. In my case it was cheaper to run power from the house.

3-phase might be charged differently anyway. Wouldn't hurt to ask.

JKJ

[Bruce Wrenn]

If you put your shop on a separate meter, then most likely you will pay commercial rates, which include a demand charge. I had a well pump on a separate meter, but when Duke Energy took over Progress, my bill jumped from around $10 to $40 a month for the same amount of electricity. Needless to say, pump is now fed from house panel, with a meter that I own to measure electric usage. I do this because it's a rental house, and well pump furnishes three houses and a church.

[William Shelley]

Where I am (Portland, OR), I am at a residential address, but the power pole on the street in front of my house has two transformers on it. I was given a really rough guesstimate for 3-phase service by a technician that was fixing my service after a tree knocked it out; he said that I could *probably* get 3-phase service if I paid for the third transformer that was needed. Which would run about $2000 to $2500. It was unclear whether that included labor or whether I would be responsible for paying for installation labor as well as the transformer part itself.

You might be able to work something out with your power company. A 3-phase panel is not much different in cost compared to a single-phase panel. Definitely more efficient than running a phase converter.

[Mike Heidrick]

I am not a qualified electrician
I did my own power upgrade
Poco signed off

I put two 200amp disconnects after the meter at the house after the 400 amp service entry upgrade was done.

Off one disconnect I ran 200amp to the new shed.
In that panel I had a 100amp 1phase breaker that feeds my RPC box
That RPC box feeds a 3phase lug only circuit breaker box (lug only means no main disconnect at the top)
I ran 3 phase circuits/outlets to three phase breakers that I installed in that 3-phase lug only box.
I also wired for start and stop controls by the outlets for the RPC box/motor