# Wiring a 480V Single Phase Circuit

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• posted on July 16, 2004, 4:37 pm
How do I wire up a 480v Single Phase circuit? I'm familiar with 480V 3P but not single. The machine has a preinstalled 3-wire cord, one of which is a ground so I'd only be using twom wires.
Also what exactly does poles mean? Like a circuit breaker is either 1-2-3 poles, is that the same as phase? Thanks.
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• posted on July 16, 2004, 5:15 pm

"Single phase" 480 is just like single phase 240 residential service, only at a higher voltage. It's called single phase because the voltage is derived from a center tapped transformer fed from one single primary.
I've never seen a single phase 480v service. 480 is commercial/industrial in nature and it's generally supplied as 3 phases.
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<%-name%>
• posted on July 16, 2004, 7:41 pm

I think "poles" means "hots" in this context. You have two.

I think he's just pulling two hots (out of three) from a 480V three phase feed.
At that voltage, I'd normally hire an electrician just to be _damn_ sure I don't do something dumb.
Most 120V stupidities are survivable. I consider 480V instant death.
[During the ice storm we wired a 600V three phase 200Kw generator. In an emergency, you gotta do what you gotta do. But you can damn betcha we were careful, and warned everyone that sticking one's hand into the step-down transformer was not just dangerous but instant death. They paid attention.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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<%-name%>
• posted on May 7, 2015, 6:57 pm
replying to HA HA Budys Here, Greg Epperson wrote:

at a

a
480 single phase is simply using 2 of the 3 hot legs. Phase to phase is 480, Phase to ground is 277vac which we use only for lighting.
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<%-name%>
• posted on May 8, 2015, 2:14 am
Greg Epperson wrote:

It's funny how these old threads pop up now and then. But anyhow, single phase in my little world can be 480 line to line and 480 line to ground. I think it's called corner ground delta. Some rural utilities here in Nebraska use it to supply irrigation well motors. We run four wires from the service disconnect to the pump panel. The neutral and equipment ground are connected in the meter. The grounded leg isn't generally supposed to be fused.
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• posted on May 8, 2015, 2:34 pm
Dean Hoffman wrote:

Oops. Dummy attack on my part. What I described above is one version of 3ø 480. We also do have single phase 480 which is just double normal household voltage. We add a phase converter to create 3ø 480 to power irrigation systems.
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<%-name%>
• posted on May 9, 2015, 6:58 am
On Fri, 08 May 2015 09:34:05 -0500, Dean Hoffman

I have seen a lot of 240 corner delta for sewer lift pumps. The service looks exactly like regular 120/240 except it is fed from 3 transformers. (2 pole breakers with a neutral bus). The first time I saw one it had me going fir a minute. They had 3 phase pumps on something that looked like single phase
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<%-name%>
• posted on July 16, 2004, 5:50 pm

This is Turtle.
480 volt single phase motors / equipment is very rare to say the least. There is only one i know of and it is the 480 volt HVAC rooftop systems which have 480 volt condenser fan motors on them. First you have to get 480 volt service to the building which only comes in 3 phase service and just use two of the hots of the 3 hots for power. If your thinking of running this at your house. the cost is going to be high to get 480 volt service to your house. The electric company will supply you with 480 volt service for about \$4K atleast and then you have to be set up to have the switch box for the 480 volt serice.
Now you can look into getting a buck and boost transformer and get 480 volt service out of your home 220 volt service. That will run you about \$2K atleast.
You got me here with what you would have that runs on single phase 480 volt that could be useful to you. It would be nice to know what it is.
TURTLE
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<%-name%>
• posted on July 17, 2004, 3:11 am

There is

480
to the

of the

is
company
have to

volt
atleast.
volt that

Hello, Turtle.
You gots me there too--mebbe he found some lights for cheap and is gonna grow dope or something.....
Now for a small load, a transformer for 220/440 shouldnt be too expensive on the surplus market though--Ebay, perhaps.....
--

SVL

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<%-name%>
• posted on July 17, 2004, 5:35 am

This is Turtle.
I have very seldom that a small load on something that uses 480 volts to pull it. You use 480 volt service to get it on for power of anything using it. other than that 220 volt service will run a great deal and easler to find power for it.
Awwwwww E-bay for quality stuff. Not Me.
TURTLE
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<%-name%>
• posted on July 17, 2004, 5:57 am

of
least.
have
service
hots
cost
you
expensive on

pull
other
for
Okay--agreed......
Still he leaves me to wondering what exactly is it he is trying to fire up here ???
I have transformers do this 220/440 and vice versa but alway for 3 phase stuff.
--

SVL

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<%-name%>
• posted on July 16, 2004, 9:58 pm

480 volt single phase is any two phases line-to-line of a 3 phase 480 volt system. If you had to ask a simple question like that, it would be in your best interests (and possibly others) NOT to be messing with it. Call a qualified Commercial/Industrial electrician.
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<%-name%>
• posted on July 16, 2004, 11:26 pm

your
Poor description--two phases ???
--
SVL

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<%-name%>
• posted on July 17, 2004, 2:03 am

Not really. "Two phases from a 3 phase circuit" is a perfectly reasonable way of saying it. Doesn't make the resulting circuit two phase tho. It's single phase. Hint: if you were to scope one hot relative to the other, it's still a simple sine wave.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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<%-name%>
• posted on July 17, 2004, 2:38 am

of
volt
in
a
Yes, really....
"Two phases from a three phase circuit" would better describe a circuit connected to a three phase supply through three wires but having no load across one of the phases.
Hint: our shop has a single phase service at 400 amps, we buss 170 amps of this to generate our own three phase power via rotary transformer in order to supply the machinery.
At any rate, a better description IMO would have been something like " a two wire service, usually one phase of a three phase supply"
--

SVL

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<%-name%>
• posted on July 17, 2004, 7:47 am

480V
either
480
Call
One phase to neutral of a 480 volt 3 phase supply is single-phase but the voltage is only 277 volt. The OP wanted to know what single-phase 480 volt was. Chris was absolutely right, whenever 2 phases of a 3 phase system are combined, the resultant sine-wave is single-phase. (It's called single-phase because _that's_ what it is.)
On a 277/480 volt 3 phase Wye connected system (which is VERY common and most likely what the OP has): Single-phase 277 volt is one phase to neutral. Single-phase 480 volt is any two phases, line-to-line.
The same is true for the also so very common 120/208 volt 3 phase Wye connected system: Single-phase 120 volt is one phase to neutral. Single-phase 208 volt is any two phases, line-to-line.
Like Turtle said, a single-phase 480 volt load is very uncommon. Usually you'll see single-phase 277 volt loads (one phase to neutral, very common for Commercial lighting) sharing the neutral on 3 phase branch-circuits, or 3 phase 480 volt (with no neutral) for motor loads.
One example of a single-phase 480 volt load, though, is Commercial parking lot lighting. While 277 volt for parking lot lighting is more common, in somes cases the light ballasts are sometimes connected single-phase 480 volt (any two phases line-to-line), when the runs are very long. A 3 phase 480 volt feeder is provided and the load is balanced accordingly. That is, the first light pole is connected phase A to phase B. The second light pole is connected phase A to phase C, the third light pole is connected phase B to phase C, then repeat for each additional light pole.
Another example of a 480 volt single-phase load is a control transformer for a motor controller. Usually the motor circuit is 3 phase 480 volts, but the desired control voltage is 120 volts. In that case, a single-phase 480 volt (line-to-line) control transformer is connected across any two phases of the feeder (properly fused, etc) and steps it down to the 120 volts.
Like others have stated, I'd like to know what the 480 volt single-phase load is that the OP is talking about. If I were to guess, I'd say something with a heating element. That's why I told the OP to call a qualified COMMERCIAL or industrial electrician, because if the load is really single-phase 277 and he slaps 480 single-phase on it, it's toast. Plus there are other, mostly safety issues, that he probably isn't aware of.
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<%-name%>
• posted on July 17, 2004, 5:42 pm
I originally thought it might be a heater too, as I've seen very few single-phase 480 motors. Many of the mid-sized infrareds I've seen are 480 single phase... the bigger ones above 7 kW or so are three phase but can be wired single if you've got the amps.
Dope growing is something I've heard these things are used for.... my brother's a police officer and has told me some of the stories on these nutty hookups. I'm also told that in some areas they ask the power company to report 'unusual' high residential loads to the cops for further investigation. They even have heat-sensitive cameras so they can sit outside your house and look for warmer rooms.
It would be interesting to see what the OP has here, and what he wants to do with it.
Jake
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<%-name%>
• posted on July 18, 2004, 12:04 am
Jake wrote: ...

Ah, the 4th amendment. How I miss it.

I wonder if he (the OP) really wants "single phase" or is misunderstanding his own needs.
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<%-name%>
• posted on July 19, 2004, 6:46 pm

Out of curiousity, I did a few google searches.
H'm. At least some commercial grade grow lamps run at 480V.
See, for example, the GLX series of fixtures:
http://www.poly-tex.com/pages/accessories/lighting.html
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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<%-name%>
• posted on July 19, 2004, 8:00 pm
Do any of you guys realize what "phase" means? It's not -just- the hot wire - there also has to be a phase difference in the voltage in each wire to generate the required voltage IFF it's more than a single-phase system. 480Vac single phase is pretty standard stuff in industry as is showing up here.
Pop

used for.... my

stories on these

480V.
named after them.