Delta High Leg

[Marty Funkhauser]

Hello, curious why the high leg in the panel isnt required to be C phase to match meter. I heard pre 1975 this was the case. So why the change to B phase? Thank You.

 

[ActionDave]

I think it's because B is in the middle whether you go left to right, right to left, front to back, or back to front.

 

[ptonsparky]

I think it's because B is in the middle whether you go left to right, right to left, front to back, or back to front.

Sounds good. I never did know why.

 

[kwired]

I think it's because B is in the middle whether you go left to right, right to left, front to back, or back to front.

Top to bottom or bottom to top in gear that has horizontal bus, until you run into gear that also has 4th similar bus for the neutral

 

[Marty Funkhauser]

I think it's because B is in the middle whether you go left to right, right to left, front to back, or back to front.

intersting. thank you

 

[g-and-h_electric]

When I was an "apprentice" I was told that the meters did not read the "high leg", in the "A-base " meter trims (before socket meters), seeing as how the "high" leg has to be used with either A, B, or A+B. Having the high leg on C in the meter trim just became convention then. Something else to note is how FPE (dirt word I know) handled high leg delta in a single phase panel at one time....

Once upon a time had a boss who knew that B wasnt metered and tapped the office space heater and window AC off of it. Aside from the breaker not being listed, I couldnt handle the lack of ethics in doing that....... I didnt stay there long!

 

[kwired]

When I was an "apprentice" I was told that the meters did not read the "high leg", in the "A-base " meter trims (before socket meters), seeing as how the "high" leg has to be used with either A, B, or A+B. Having the high leg on C in the meter trim just became convention then. Something else to note is how FPE (dirt word I know) handled high leg delta in a single phase panel at one time....

Once upon a time had a boss who knew that B wasnt metered and tapped the office space heater and window AC off of it. Aside from the breaker not being listed, I couldnt handle the lack of ethics in doing that....... I didnt stay there long!

They showed a "delta breaker" arrangement for that. This was something that was not limited to just FPE, pretty much everybody had a similar breaker at one time. Code eventually prohibited their use. Problem with them is you could turn off the two pole main or feeder to the panel but still have possible back feed through the three phase load from the high leg and it would put voltage on the other two buses in the panel and depending on resistances of the circuit paths could be up to 208 volts.