Identifying this Switchboard Panel 240-Delta?

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MJRobinson

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Chico, CA, USA
Hello,

I need some identifying the voltage of this panel.

I thought it was 240-Delta 3-phase, 400 amps.

Can someone help with this nameplate?

See attached.

Thanks,

Michael
 

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Appears to me its rated for 240/120 3 phase 4 wire delta or 3 phase 240 delta.
 
Can't see the far terminal of the right transformer but if it ties to the far left terminal on the left unit (guessing it does) then you should have a high leg delta system there. Can't tell the voltage without seeing nameplates or measuring.
 
The panel itself is rated for use on 208Y120 3 phase 4 wire, or 240/120 3 phase 4 wire delta, 400A with a 100% Neutral. The panel "doesn't care". Some of the breakers USED inside of that panel might care because if it is 3Ph4W delta, any 1 or 2 pole breakers plugged onto B phase would need to be rated for "straight" 240V, not "slash rated", meaning not 120/240V. 3 pole breakers wouldn't matter, neither would it if you have 208Y120V.
 
Follow up - Photo of Sub-Panel

Follow up - Photo of Sub-Panel

Attached is a photo of the sub panel for clarity.
 

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Again it appears the supply is 120/240 three phase 4 wire - with a high leg.

The panel is rated for such, but 208/120 supply would still fall within the panel rating.
 
The panel itself is rated for use on 208Y120 3 phase 4 wire, or 240/120 3 phase 4 wire delta, 400A with a 100% Neutral. The panel "doesn't care". Some of the breakers USED inside of that panel might care because if it is 3Ph4W delta, any 1 or 2 pole breakers plugged onto B phase would need to be rated for "straight" 240V, not "slash rated", meaning not 120/240V. 3 pole breakers wouldn't matter, neither would it if you have 208Y120V.

Thanks,

Great explanation.
 
Good point.
Took me a while to get it, but I see it now. That's a single pole breaker on B phase...
Single pole QP breakers are only rated 120V.

It's either 3-single poles or a 3 pole missing the handle tie, not real clear but also looks like 30A.
 
It's either 3-single poles or a 3 pole missing the handle tie, not real clear but also looks like 30A.

Yep, you might be right, it appears to say "Day Shed" above the first breaker, which might mean it's a feeder to an out building, so should have been 3 pole. But either way it's a violation.
 
The panel itself is rated for use on 208Y120 3 phase 4 wire, or 240/120 3 phase 4 wire delta, 400A with a 100% Neutral. The panel "doesn't care". Some of the breakers USED inside of that panel might care because if it is 3Ph4W delta, any 1 or 2 pole breakers plugged onto B phase would need to be rated for "straight" 240V, not "slash rated", meaning not 120/240V. 3 pole breakers wouldn't matter, neither would it if you have 208Y120V.

I have seen this mentioned before, when would you EVER use a 1 pole breaker on "B phase?? I was taught high leg is unusable for 1 pole feed.
 
I was taught never to use it and I don't but you can hook up to the high leg and make stuff like motors or lights work.

I don't even see how it would run a motor, because if you look at it from a vector stand point it is really sharing 2 phases B phase and half of A or C. A light maybe but not a motor.
 
I don't even see how it would run a motor, because if you look at it from a vector stand point it is really sharing 2 phases B phase and half of A or C. A light maybe but not a motor.
It will run a single phase motor just fine, at 208V and with limited current because it has one and a half winding resistance and probably open delta (higher impedance feering the B wire.)
It will also run a three phase motor as well as a similar delta or open delta since the neutral is not used. But three single pole breakers will not fly for that.

Sent from my XT1585 using Tapatalk
 
You CAN use it, but it's DIFFICULT to use it, because as said, MOST of the 1 pole breakers are not going to be rated for more than 120V L-G. But if you use bolt-on breakers, you can do it if you pick the CORRECT breakers. Since I know Siemens, an example is that the QP plug-in breakers are only rated 120V, as are their bolt-in sisters, the BQ series. But if you use the BQD series bolt-ons, i.e. what you would use in a 480/277V panelboard, the single pole breakers are rated for 277V, so those can be used.

The only plug-in breaker arrangement that I know of where you can do this is an I-Line Square D panel. That will cost someone a LOT more money just to get a 208V 1 pole plug-in breaker. That makes it never worth it.
 
You CAN use it, but it's DIFFICULT to use it, because as said, MOST of the 1 pole breakers are not going to be rated for more than 120V L-G. But if you use bolt-on breakers, you can do it if you pick the CORRECT breakers. Since I know Siemens, an example is that the QP plug-in breakers are only rated 120V, as are their bolt-in sisters, the BQ series. But if you use the BQD series bolt-ons, i.e. what you would use in a 480/277V panelboard, the single pole breakers are rated for 277V, so those can be used.

The only plug-in breaker arrangement that I know of where you can do this is an I-Line Square D panel. That will cost someone a LOT more money just to get a 208V 1 pole plug-in breaker. That makes it never worth it.
:thumbsup:
 
There are two pole breakers rated straight 240 volts. They are not something commonly found in stock at your supply house and they are not cheap if you order them.
 
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