sub panel is 120/240 SINGLE PHASE BUT MAIN PANEL/METER BREAKER 240 VOLT THREE POLE

[Designer101]

The sub panel look old zinsco 225A Rated which we are trying to upgrade and is rated 120/240 volts with 100A MAIN BREAKER
its connected to meter breaker panel like a 50 FT away to another property and looks like Is double tapped to existing breaker ( three pole 240 volts per sticker)
Now my question here is How common are these three pole 240 volts ( are these 240 volts High leg delta set up FROM THE TRANSFORMER).
can I back feed these meter breaker From the Sub panel downstream??
pictures attached as pdf

 

[jaggedben]

It's definitely possible it's a 240V high-leg delta with the phase having the neutral feeding the subpanel. It's also definitely possible that there's another three-phase panel or appliance somewhere. That might be one single phase circuit and one 3 phase circuit we're seeing double tapped on the main breaker.

It's also possible that the 3-pole breaker is a red herring and it's just a 120/240 split phase service like the label below the meter suggests. I can't really tell which wires are neutral in the photo.

It's not possible to tell which it is from here.

What I can tell you from here is that I wouldn't backfeed a Zinsco subpanel with that many circuits in it. Too much liability. This facility needs some upgrades.

I can also tell you not to make any plans to backfeed that main breaker without understanding what's going on with the double tap. And that if the service is a high-leg delta, you should ask the utility how many phases they want you to backfeed.

 

[hillbilly1]

I agree with Jaggedben, it most likely a delta service, since it’s overhead, it would be real easy to verify visually. The double taps are probably single phase loads, the single tap, probably the high leg.

 

[Designer101]

It's definitely possible it's a 240V high-leg delta with the phase having the neutral feeding the subpanel. It's also definitely possible that there's another three-phase panel or appliance somewhere. That might be one single phase circuit and one 3 phase circuit we're seeing double tapped on the main breaker.

It's also possible that the 3-pole breaker is a red herring and it's just a 120/240 split phase service like the label below the meter suggests. I can't really tell which wires are neutral in the photo.

It's not possible to tell which it is from here.

What I can tell you from here is that I wouldn't backfeed a Zinsco subpanel with that many circuits in it. Too much liability. This facility needs some upgrades.

I can also tell you not to make any plans to backfeed that main breaker without understanding what's going on with the double tap. And that if the service is a high-leg delta, you should ask the utility how many phases they want you to backfeed.

Yes sub panel needs to be changed no doubt, we are sending tech to find out more details on the meter breaker. Thank you