OT - Generator for home shop - 3 phase to single?

[Iron Filing]

Hello,
My machines are all currently located in a barn some distance from the house. Unfortunately, this means that I can't actually power some of them because the wiring going over there is too small (a single 15A circuit). I could upgrade the wiring, but I wanted to use a generator instead.

I plan to buy a used generator, but I can't control what is listed. So, I get a generators which are single and 3-phase. I understand that 3-phase power would be quite useful if/when I manage to go from a hobbyist into being a professional. But inevitably, some of the equipment is going to be single phase. I'm currently in need of 15KW of single phase power. Most of it for my buzz box welder.

How hard/expensive would it be to convert from 3-phase generator to single phase?

Thanks!

 

[cathead]

I have run generators a lot over the years. My advice would be to put your money into upgrading
your wiring unless your shop is a very long distance from the house. A 5000 watt generator will burn
up to 5 gallons of gas in an eight hour stretch so the operating cost could easily exceed fifteen dollars a day.
One needs to consider the price of the generator as well as fuel costs in making a good decision.

Most three phase generators can be used for single phase operation if you use one pair of the output wires.

Also, if you decide to upgrade the wiring, one can use an RPC to generate some three phase power for
your shop.

 

[MyLilMule]

I would go for the 3 phase generator, if the cost differential isn't too great. You can get single phase by using one leg (110v) or two legs (220v) and the neutral line from the generator (along with the ground, of course). If the generator does not provide a neutral line, a simple transformer can provide you with 220 volt single phase. The transformer would have to be sized appropriately. My primary concern would be how clean the power is coming off any generator. For most things, not a big deal, but for anything that has any kind of electronics in it, you're going to want some clean stable power.

 

[Ulma Doctor]

Just use 2poles of the 3phase and a ground, problem solved

 

[matthewsx]

I agree, upgrade the power, it's a capital expense that adds to the value of your property.

Plus, any inexpensive 15kw generator is going to be loud, is there anyone else in the house that would be affected? How about neighbors?

It's not only the noise and fuel costs, you will need to maintain and eventually replace a generator. Once you pay for running the wire and installing a sub-panel your only extra expense will be whatever power you use.

Check with your local utility company to see if they can run direct to your building too.

John

 

[markba633csi]

How long a wiring run are we talking about? I would do the wiring route myself, rather than a genny
Plus you could run your machines in the dead of night without bothering the neighbors
Having to start a generator every time you want to machine something sounds like a pain in the rear to me

 

[Iron Filing]

How long a wiring run are we talking about? I would do the wiring route myself, rather than a genny
Plus you could run your machines in the dead of night without bothering the neighbors
Having to start a generator every time you want to machine something sounds like a pain in the rear to me

I'm not too concerned about having to start the generator.
The noise, OTOH, might annoy people. I'll have to investigate further (I may be able to dampen the noise with an enclosure). I'm hoping not to have to work into the sleeping hours of the night -- even as a pro. But then there's Murphy's law and all that.

For those of you who REALLY want to know why a generator is preferable, here's the wall of text.

The barn is ~300ft away from the house. At that distance, buying 0/2 aluminum wire would be the cheapest option. I could move it closer, but I'd have to do a bunch of tree cutting and stump removal. After that, I'd have to have the main electrical panel redone to fit extra breakers (I'm not concerned with the value of the house. Like, why would you setup a shop just to sell the house and shop?) And all that is without taking into account that the electrical going from the transformer to the house is about 100ft too long according to code (This means I'm closer to the voltage drop limits coming into the house than I should be). How it passed inspection about 20 years ago I have no clue. Now you might say to me that this *should* be fixed. And I agree. But I don't want to spend the next few years trying to fight the electric company to get that done. Things work, at least for now, and I'm happy with that.

 

[markba633csi]

Every situation is different, and I see your predicament totally

 

[RJSakowski]

Our electric service comes in at our barn and then a 300 ft. run of 4/0 to the house. We have an all electric home, including electric range, hot water heater and central air. My basement shop has a 220 amp welder, two milling machines, two lathes, and and a bench grinder. I also run my woodworking shop including a 2hp 240 volt table saw, radial arm saw, 6" jointer, 12" planer, compound miter saw and belt sander..

We have never had a problem with brownouts.

 

[tq60]

For long runs, 300 ft is not, buck/boost transformers are common.

They boost up to 600 volts rather than drop back at other end.

Higher voltage results in less current. Watts are watts regardless of voltage.

Lower current reduces voltage drop.

It's not cheap, but it works.

Another option is to get direct power to the barn from your utility.

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