residential 3 phase?

[Tuff]

Is it possible to wire up residential service with 3 phase service? My gut instinct says no, but I was just curious.

[aametalmaster]

If it runs by your house, but it isnt cheap. I have an industrial park up the road from me. The cost to run the lines was real high. Like $10,000...Bob

[Kdredneck]

There is no reason why you couldn't do it. If you want to pay for it. You would also have to make sure to get all 3 phase equipment, like the meter and panels.

[hankj]

You can install 3-phase anywhere it is available. As said, you'd have to replace your service entrance equipment. If you get 3-phase/four wire, you'd have no problem with downstream apparatus. If you wind up with a 208V "wild" leg, that can be a PIA for the downstream stuff, and for your existing 120V appliances!

All in all, it's not hardly worth it unless you have enough load to justify the expense.

Hank

[MAC702]

If you get 3-phase/four wire, you'd have no problem with downstream apparatus. If you wind up with a 208V "wild" leg, that can be a PIA for the downstream stuff, and for your existing 120V appliances!

I recommend a wye three-phase set-up in residential settings. In fact, that's what I've been installing here for the last six months. You don't get the "wild leg" like you do with the delta three-phase. So you get true 120V between EVERY phase and the neutral. The trade-off is that your two-pole power is only 208V instead of 240V, so stoves and other loads have to be rated for that, but it's certainly available. Most residential is mostly 120V so it's worth it, if you need to go three-phase for some other reason; wish I could.

[Kdredneck]

But the "wild" leg is so convenient, it makes the lights burn so much brighter on that phase. Hmmm, they just don't last very long. Computers seem to like it too. Never done it myself, just heard the stories.

[newtoit]

Once upon time, I asked for it. They laughed. Even if I had the money, they would not do it. Something to do with being deep in a residential neighborhood, and that I would never use enough power to justify it. My last months electric bill was over five hundred dollarss and that was just household stuff, nothing hobby or industrial in nature. And because I put on an addition, and do not like too many outlets on a circuit, I will soon upgrade my 200 amp service to 400 amps. That won't increase my usage, but will provide adequate room for expansion.

I had a buddy with a cellar machine shop, three bridgeports, two lathes, and an assortment of the usual small stuff. He ran a three pahse converter, never had a problem. Never had much of an electric bill. Can you say power factor? Worked for him.

[tooldude56]

I recommend a wye three-phase set-up in residential settings. In fact, that's what I've been installing here for the last six months. You don't get the "wild leg" like you do with the delta three-phase. So you get true 120V between EVERY phase and the neutral. The trade-off is that your two-pole power is only 208V instead of 240V, so stoves and other loads have to be rated for that, but it's certainly available. Most residential is mostly 120V so it's worth it, if you need to go three-phase for some other reason; wish I could.

I've had 3-phase for around 7 or 8 years at my residential address.What I have,is a Delta 4-wire 240 volt system that has a wild leg.The way this works is,I have 240 volts,leg to leg, betweeen any of the 3 hot legs,but I have 120 volts from either of 2 of the hot legs to neutral and 208 volts from the wild leg to neutral.This is not confusing at all because of the way that I have it set up.My main power comes from the transformers,then is split at my shop,where I have 2 meters,1 for 3-phase and 1 for single-phase.The single -phase meter feeds a 200 amp panel that supplies a 100 amp breaker that feeds the house and supplies all of my 1-phase needs in the shop.The 3- phase panel is used mainly for the 3-phase in my shop,but can also supply 120 volt or 240 volt single-phase power,if needed.What is real handy with my machines,is the fact that I can run a neutral with the power to a machine,like my lathe,mill or surface grinder and supply 110 volts for control voltage,eliminating the need for control transformers at the machine.I was real lucky when I got my 3-phase power,because the power company did'nt charge me a dime for connecting me,though there was a 13,600 volt line within 15 feet of my shop,so it was quite convenient for them.I did,however,have around $1,000.00 in to a used 3-phase panel,breakers,masts and wire,but being a residence,I was allowed,by the inspector,to do my own installation of the 3-phase setup,with out the need of having to hire a licensed electrician,like you would need in Michigan,if it were a commercial building,but my industrial electrical background was also known to the inspector.The power company came to my place and accessed my combined horsepower requirements and realized that it could'nt be done with single-phase.The great part of my setup.is that I am the only service hooked to my transformer bank,so my voltages fluxuate little,at high usage times of the day,unlike areas where there are many homes hooked to a single transformer.

tooldude56

[hankj]

Good info, Tommy. That'll throw some cold water on the folk who think it's an easy conversion.

Not to say you should't go for it - just recall Tom's $$ figures.

Hank

[MAC702]

I've had 3-phase for around 7 or 8 years at my residential address.What I have,is a Delta 4-wire 240 volt system that has a wild leg.The way this works is,I have 240 volts,leg to leg, betweeen any of the 3 hot legs,but I have 120 volts from either of 2 of the hot legs to neutral and 208 volts from the wild leg to neutral.This is not confusing at all because of the way that I have it set up.

I agree that if you have a significant portion of your main load being either 2-pole or 3-pole loads, then a Delta is the way to go, for true 240V. But for most people only casually interested in a 3-phase set-up, the majority of their loads are probably 120V and they just want a few (or one) 3-phase machines. In which case, having a Delta set-up that limits your 120V loads to only two of the phases makes it difficult (and sometimes impossible) to balance the panel, sometimes to the point of losing the efficiency that you gain by going to three phase power.

In residential settings, power factor is often not a factor because of the difference in the way the utility bills residential versus commercial, and therefore it is often very beneficial to the consumer to go with low kilowatts and ignore the reactive power draw from things like large rotary phase converters and other industrial motors.

Good points!

[TOMWELDS]

In my area, if its on the pole, you can get 3 phase. The main requirement (for both residential and commercial) is you have to have at least one 7 1/2HP motor. Its not too common, but there are some neighborhoods here that have 3phase.

[MXtras]

I requested three phase at home (Virginia) and they said no - not to a residence, but they sent out a very helpful guy to see why I was requesting it. He suggested that I upgrade from 200 amp to 400 amp service - at their expense once the meter base was installed and inspected. I would have my very own transformer - all to myself. I am not going to do it, though - I went out and leased a commercial building with three phase.

Scott

[MAC702]

He suggested that I upgrade from 200 amp to 400 amp service - at their expense once the meter base was installed and inspected. I would have my very own transformer - all to myself.

Here, if you have an older house that still has overhead lines coming in to a mast, you can upgrade from a 100A to a 400A service and they don't even change the wires.

[TOMWELDS]

Mac, ive seen that here. Sometimes its funny. Parallel 500's and the utility gives you a #4AL...lol...They go by the demand for what you have. Plenty of burnouts around here.

[precisionworks]

My local utility company quoted over five grand to set two small transformers & run fifty feet of overhead service.

Rotary Phase Convertors (RPC's) are the method used by many who have single phase & need three phase for one or two or three machines. Here's a link to a RPC forum:

http://www.practicalmachinist.com/ub...?ubb=forum;f=3