What's new
What's new

220vac 3 phase?

Ewindward

Plastic
Joined
Sep 13, 2018
Looking at a new shop space today and the panel is marked for 220vac 3 phase. I don't know much about electrical but 220 3 phase is something I've never heard of and I'm not sure it even exists. Can anyone give any insight on this?
 

Attachments

  • 20190524_161518.jpg
    20190524_161518.jpg
    85.6 KB · Views: 354
  • 20190524_161524.jpg
    20190524_161524.jpg
    86.8 KB · Views: 415
  • 20190524_161542.jpg
    20190524_161542.jpg
    87.4 KB · Views: 338
Last edited:
Nothing unusual about 220V 3-phase. 3 phase motors with windings for either 220V or 440V are extremely common, toegether with all the associated starters, soft-starters, and VFDs.

My shop has a 200A 220V single-phase supply, which I convert to 220V 3-phase for the larger machine tools.
 
So you dont think there is anything too sketchy about this set up? I plan on having my electrician take a look before I sign any lease anyway. Just thought this was a bit out of the ordinary from what I have seen.
 
That's quite common. Both of my buildings in Tennessee I rent out are 220 Delta 3 phase. Granted the newer stuff is 208 Y 3 phase and is less likely to bite you in the ass if you wire something out of phase. My boxes are 220-220-110 so the only real trick is not tapping into the 220 for your standard wall sockets.

I bought a new Sony Mill station CNC and accidentally hit it with the 220 leg. smoked a brand new $18k machine on day one.
 
Can you crack the front of the panel open? There's nowhere in that panel arrangement for a 3 pole breaker. Even if you have the supply, you'll need a different panel to put a 3ph breaker in.
 
Unfortunately I'm not at the space right now and wont have access again until tuesday so I wont be able to take a peek into the panel. I was thinking the same thing about the 3 pole breaker. I cant wrap my head around what the hell this is.
 
I sure could be wrong but it looks to me like the panel was identified incorrectly and what you actually have is 220v single phase. There are notations for 110v circuits and the neighboring breakers look like two pole jobs to me..not room for a 3 pole breaker which would be needed for a 3 phase system. I see 120v and 240v DP single phase breakers.

Stuart
 
All(?) commercial power in the US (on the poles, from the power company) is distributed as 3-phase.

There are two versions according to the arrangement of the three transformer windings:

3-phase Delta requires three wires. These are the wires you usually see on power poles.
The three windings are arranged in a triangle, with two windings connected at each point.

3-phase "Y" requires four wires.
The three windings are arranged like the letter Y, with one end of each meeting in the center.

Most machines of any size require 3-phase power. Only the smallest ones run on single-phase.

2-phase (aka phase quadrature) power does exist, but it's quite rare.
I don't know of any area where it's commercially generated or used.

The pole-mounted transformers convert 3-phase to single-phase for residential and small commercial use.

- Leigh
 
Again, it's wrong. That is a single phase panel and USA power is 120/240. Unless we are going back to the 60s, that is not 220V.
 
I am a retired lineman and grid operator what you most likely have is 120 / 240 three phase which is connected Delta on the secondary. In the old days and looking at the panel it is fairly old the voltage was refereed to as 110 / 220 but in today's world nominal voltage is + or - 5% of 120/240 for delta or 240/480 is the other delta connected voltage. If the secondary is Y connected the voltage will either be 120/208 or 277/480. To confuse things a little more the delta connected services will have a wild leg in the case of the 120/240 3 phase voltage you get 3 legs phase to phase of 240 volts and 2 legs of 120 volts to ground the wild leg to ground will measure approximately 208 volts. If the delta service is 240/480 you will have 3 legs of 480 phase to phase & 2 legs of 240 volts phase to ground and one phase of 277 volts phase to ground. It is important to note the 208 single phase volts to ground are not used and neither is the 277 volts to ground on the 120/240 volt or the 240/480 volt service.

Mike
 
Indeed. You will see some things marked as 220, some as 230, some as 240. Reason being, 220v used to be the standard, but then the grid reached capacity. Power (watts) is voltage times amperage. Wires have a maximum amount of current (amperage) you can run through them for a given size (And temp rise, etc etc), so in order to increase the total power that could be delivered they increased the voltage a hair to 230v. Most devices and equipment are fine with +/-10%, so that was no big deal. Then some years later, the limit was reached again, and so the standard was increased again to 240V.

The current 240V is usually allowed a +/- 5% as well, so really it could be as high as 253V. I find my power comes in around 248-252V, so they're getting everything they can out of it. Modern equipment is designed with this in mind and is fine. My older machines want 220 or 230V though, so I run a pair of buck/boost transformers to reduce the input voltage to their nominal input voltage. Might be fine, but for a couple hundred bucks it gives me peace of mind.

When in doubt, the multimeter is your friend.

You can also sometimes ask the power company to adjust the transformer on the pole, and sometimes your machines may even have built in transformers to account for this (My HAAS mills do).
 
USA power is 120/240. Unless we are going back to the 60s, that is not 220V.
It makes sense to distinguish between 208, 220, and 277, because those are wired up quite differently. Getting fussy over 220/230/234/240 is not productive, ignores lingering regional power company differences, mostly just confuses the issue, and in this situation completely misses the real question: single phase or three phase.

There are two possibilities on the table: mislabeled single phase panel, or a panel fed by three-phase with only single-phase branch circuits (obviously asymmetrically).

[Added in edit:] In the case of three-phase panel, the two-slot breakers would be drawing from two of the three phases. As far as downstream equipment is concerned, the result is single-phase supply.
 
It makes sense to distinguish between 208, 220, and 277, because those are wired up quite differently. Getting fussy over 220/230/234/240 is not productive, ignores lingering regional power company differences, mostly just confuses the issue, and in this situation completely misses the real question: single phase or three phase.

Actually it is important and something people seem to ignore right up until it bites them in the ass. I recall pointing out a voltage issue to a Tree owner here not a month ago that was causing the VFD brake circuit to trip out. I have also been called to help on electrical only to find out they are "concerned because their 220V panel is reading 242V".....

I have no doubt the panel is being fed by 2 legs of 3 phase power, but if a panel is single phase, it should be labeled as such.
 
I don't think that is correct. I belive that is a 3 phase panel. Check out this ebay ad for the same panel model number...........

Square D QOC-30 QO Load Center Electrical Cabinet | eBay

Interesting. Could be that the little dividers pop out/twist out? Look at the bottom of the 2-pole row. There's a lone single pole breaker.

In any case, taking off the front of the panel would tell us pretty conclusively if there is 3ph present or not.
 
I am a retired lineman and grid operator what you most likely have is 120 / 240 three phase which is connected Delta on the secondary. In the old days and looking at the panel it is fairly old the voltage was refereed to as 110 / 220 but in today's world nominal voltage is + or - 5% of 120/240 for delta or 240/480 is the other delta connected voltage. If the secondary is Y connected the voltage will either be 120/208 or 277/480. To confuse things a little more the delta connected services will have a wild leg in the case of the 120/240 3 phase voltage you get 3 legs phase to phase of 240 volts and 2 legs of 120 volts to ground the wild leg to ground will measure approximately 208 volts. If the delta service is 240/480 you will have 3 legs of 480 phase to phase & 2 legs of 240 volts phase to ground and one phase of 277 volts phase to ground. It is important to note the 208 single phase volts to ground are not used and neither is the 277 volts to ground on the 120/240 volt or the 240/480 volt service.

Mike

Mike has it right. This is a 3-phase panel setup in Delta configuration.

AND, having 3-phase in your shop is a MAJOR plus and machines run much better on 3-phase than single phase. You will want to hire a professional electrician to sort through proper hook-up to the panel, but you can get both single phase and 3-phase power from this setup.
 
Guys!!!!

Look at Picture #3!!!
It clearly shows that there are 110V ... well somethings connected, which means that until the cover is off and picture is shown, there is no way to tell WTF is in there.

For all we know this space is a subbed off section of a larger building, supplied by a secondary, center tapped 3PH delta transformer for 3PH, single PH and 110V loads.
 
Agreed. To really know, you need to open it up. BUT, if in fact this isn't a 3phase panel, that picture one shows a REALLY misleading label.....almost criminal.
 
And to OP: my recommendation is don't sign the lease until you have an electrician checkout the panel and you know what you've got. I myself would NOT rent the facility if it was single phase only, 3-phase makes life so much easier for machines.
 








 
Back
Top