07-19-2008, 06:37 PM #1
ELECTRICIANS, 3 phase electrical question??
3 phase electrical question???
just got a new home and was wondering about 3 phase power.
Im not sure but 3 heavy line on the top of the pole is 3 phase right?
So say if i wanted a 400amp 3 phase circut in my garage i could have it brought right in from the pole without a phase converter??
07-19-2008, 07:14 PM #2
Daniel it depends, in some places the utility companies won't bring 3 phase power to a residential home so in that case you would need to run a phase converter. If you can get the power company to bring 3 phase to the house then you will need a special panel to bring the power to and be able to utilize it from there, it has to be separate from the house panel all together or you need to do some serious reconfiguring of your house circuits to use them in that panel. Also you need to know if they are running a "high" leg, which is usually B phase. You can't run anything 120 off of that leg without seeing the smoke. It can be done but its lots of work, I would go with the phase converter it's cheeper
07-19-2008, 08:06 PM #3
Like SMW said, they may not run it to a residential service. They may charge you for the time and equipment too, depends on the utility. What do you need the 3 phase for and at what voltage? Those three lines are the three primary phases. They will all be equal voltage between phases. To get the high leg SMW is talking about is done with the configuration of the transformer bank they install. A delta bank will give you the high leg. 120v, 240v and the high leg at 208v. A wye bank will give you 480/277 or 277/120 volts. In case you were wondering in that first pic what is on the pole. It's a recloser or sectionalizer. They act sort of like a breaker. There is a transformer on the pole too, to power the recloser.
07-19-2008, 08:47 PM #4What do you need the 3 phase for and at what voltage?
If i was to do it, it would be on its own panel and meter Just for the garage.
they may not run it to a residential service.
just wasn't sure if i had it at the pole or not..
I didn't have 3 phase on my old street.
and noticed i DIDN'T have 3 large line on the old pole.
07-20-2008, 10:01 AM #5
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"If" they will install 3 phase and you get 480 volts,you will have to install a transformer to drop the voltage to 240/120 volts for everything besides the machinery.Might want to check the "machinery",most can be converted to 240 three phase by switching motor leads around.(of course you might need larger starters to handle the higher amperage load). Most of the time it's cheaper and easier to install a 3 phase convertor.
07-20-2008, 10:50 AM #6
most feeded lines are 2200 volts you can get more than 1 phase from a single wire.
your transformer will most like take your 2200 volts and convert it to 120 volts x 2 to supply your house with 240 volts.
07-20-2008, 11:24 AM #7
Three phase machinery is usually just how the power is directed into the machine. In other words the components are not 3 phase or even single phase.
I have dealt with alot of metric based german engineered 3 phase stuff. We can take the same machine and wire it from single phase. It will just take alot more of the panel.
We have had a few commercial locations upgraded to 3 phase. The utility company at the first one did it for free because of how we would be commited to the power and they would get it back in the long run. At another, we had to pay close to $30 grand for the service upgrade.
Your best bet would be to contact the manufacturer and see what specs need to be met. You may have to use a buck booster to play the voltage.
Last edited by BAR BAY H.O.; 07-20-2008 at 11:27 AM.
07-20-2008, 02:01 PM #8
What is the draw and HP on your 3 phase equipment (CNC?)? 400 amp 3 phase is a LOT of power! If it has motors it needs 3 phase power to the motor. If it's 480 volts you may be able to rewire the motor to 240 BUT it will draw twice the amps. So anything it's wired to will have to be upgraded, namely the motor contactor / starter like said before and the wires themselves. To get the 480v from your existing 240v supply you would need a transformer to boost the voltage to 480 and then use a phase converter to get the third phase. If there are no motors you may be able to wire it single phase. Not sure how much any of this would cost but I don't think it would be to cheap.
What did it cost your freind to get the power and how is it billed? Call the power company and go from there.
Last edited by inothome; 07-20-2008 at 02:04 PM.
07-21-2008, 08:40 AM #9
heres what i gathered so far..
200amp 480 volt 3 phase would be fine
2 machines (20 HP motors)
each one is currently connected to their own 60amp 480 volt 3 phase circuit..
and i could have the possibility for one more 60amp 480 volt 3phase plug..
i want a 60 amp 240 single phase for the welder.
And maybe a 240 single for a big AC
there will never be a time im running everything at once.
found out it cost 12k for them to run a 200amp 3phase line to my buddy barn meter box. so I'm guessing about the same for me.
the main panel and anything else has to be there first and inspected.
basically a box right next to the house box and meter (like a duplex house).
one for the house left just the way it is. including existing garage 110 plugs and lights all untouched..
and the new 3phase meter & box with 3 connections inside the garage for the 3phase equip ONLY.
this way i could also track exactly how much electricity I'm using for business too..
Last edited by rapidacceleration; 07-21-2008 at 08:50 AM.
07-21-2008, 09:12 AM #10
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