240V-Gnd on One a one phase

[philly]

I was walking down a city street the other day and saw a panel on the side of a building that had a big orange sticker saying "Phase B to Gnd is 240V".

I was sitting there scratching my head trying to think what kind of configuration would provide this reading.

The only think I can think of is a spit phase 120/240 that didn't have the neutral grounded but rater had one of the phases grounded. Then one of the legs to ground would be 0V and the other would be 240V. This would work in a single phase panel I suppose however there really wouldn't be a "Phase B" in a single phase panel which leads me to believe it was a 3-Phase panel?

I supposed in a 3-Phase panel you could have a 240V delta system with one of the corners grounded but then you would have 240V to GND on two of the phases?

 

[infinity]

If it said "B phase to Ground is 208 volts" then I would guess that it's a 3Ø, 4Wire Delta.

 

[Phil Corso]

Was it professional looking?

Phil Corso

 

[philly]

If it said "B phase to Ground is 208 volts" then I would guess that it's a 3Ø, 4Wire Delta.

Yes I agree but it said 240V which struck me as strange

Was it professional looking?

Phil Corso

Yes it appeared to be a standard sticker like an AF label you would see on a panel. I should have taken a picture. Perhaps just a misprint but wanted to make sure I wasn't missing something

 

[Smart $]

It's a corner [B-phase] grounded delta 3Ø 3W system. Uncommon but far from rare. There's even panelboards manufactured specifically for this system. The wiring appears much the same as a 120/208V 1Ø 3W system. Grounded conductor must be white or gray.

 

[infinity]

It's a corner [B-phase] grounded delta 3Ø 3W system. Uncommon but far from rare. There's even panelboards manufactured specifically for this system. The wiring appears much the same as a 120/208V 1Ø 3W system. Grounded conductor must be white or gray.

If the B phase is grounded wouldn't the voltage to ground on the B phase be 0 volts not 240?

 

[Smart $]

If the B phase is grounded wouldn't the voltage to ground on the B phase be 0 volts not 240?

Ahhh!!! :slaphead:

@philly: Did you take any measurements? If yes, what did you get?

 

[philly]

Ahhh!!! :slaphead:

@philly: Did you take any measurements? If yes, what did you get?

I did not take any measurements, just simply a panel I saw while walking down a street.

 

[infinity]

I did not take any measurements, just simply a panel I saw while walking down a street.

So it is conceivable that the voltage on the label was a little off.

 

[Jraef]

In theory if it was a 240V corner grounded delta and A was the grounded phase, the B to ground would be 240V. But so would C to ground, so it would be odd to word the sign like that. Maybe it was because they had people used to seeing B to ground being 208V so they felt compelled to make it clear.

 

[just the cowboy]

What would 2-phase be

What would 2-phase be

In theory if it was a 240V corner grounded delta and A was the grounded phase, the B to ground would be 240V. But so would C to ground, so it would be odd to word the sign like that. Maybe it was because they had people used to seeing B to ground being 208V so they felt compelled to make it clear.

What would 2 phase be? His name is Philly could be he is from Philly and they have some real 2 phase left I think. Been a longgggg time since I worked with it.

 

[Smart $]

What would 2 phase be?

:?

 

[GoldDigger]

What would 2 phase be? His name is Philly could be he is from Philly and they have some real 2 phase left I think. Been a longgggg time since I worked with it.

If you mean what voltage would it be, that depends on what POCO chooses to deliver.
If it matches the second diagram above it would be 120V to neutral from each of the two hot lines and 170V line to line.
If it matches the third diagram (center tapped windings), it would be four separate 120V to neutral lines, with diagonal line to line being 170V and line to opposite line being 240V. (Essentially two 120/240 single phase three wire systems with a common neutral and a 90 degree phase rotation between them.)
For other line to neutral or line to line voltage options just multiply all values proportionally.