240Volt Gounded B phase - Lighting Circuits
- Thread starter blues
- Start date
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ptonsparky
Tom
- Occupation
- EC - retired
The trick is finding a single pole breaker that isn’t 120/240 rated and if you need to buy a two or three pole, you just as well use the two hots.
ptonsparky
Tom
- Occupation
- EC - retired
Depending on your breaker, it may be slash rated as well and that would make it a no go. Three poles would be good.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
There is no neutral on corner ground system. You still need EGC's though, bonding jumper goes in the grounded phase at the service or at the separately derived system whichever applies. If you are using breakers good chance you have grounded conductor as the B phase bus in the panel just use 2 or 3 pole breaker, but as mentioned it can't be a 120/240 breaker it needs to be straight 240 rated.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
If you have a 3 phase grounded B system you have two _options_.
You can treat the grounded conductor just like a 'hot' phase. Use a panel with 3 insulated bus bars, with A, B, and C all on the insulated bus bars, and then use a double pole breaker to feed your 240V single phase loads.
Or you can treat the grounded conductor as a grounded conductor, and land it on a 'neutral' bar. In this case you only need a single pole breaker to serve the load.
In both cases, however you need breakers that are fully rated (eg 240V rated both line-line and line-ground) not 'slash' rated (rated 120V to ground and 240V line to line).
Additionally the 'neutral' bar has to be rated to carry full phase current, because there is no balancing effect as seen with a true neutral.
Probably easier and cheaper to just use a 3 phase panel and 2 pole breakers.
-Jon
You can treat the grounded conductor just like a 'hot' phase. Use a panel with 3 insulated bus bars, with A, B, and C all on the insulated bus bars, and then use a double pole breaker to feed your 240V single phase loads.
Or you can treat the grounded conductor as a grounded conductor, and land it on a 'neutral' bar. In this case you only need a single pole breaker to serve the load.
In both cases, however you need breakers that are fully rated (eg 240V rated both line-line and line-ground) not 'slash' rated (rated 120V to ground and 240V line to line).
Additionally the 'neutral' bar has to be rated to carry full phase current, because there is no balancing effect as seen with a true neutral.
Probably easier and cheaper to just use a 3 phase panel and 2 pole breakers.
-Jon
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