1. ## GROUNDED B PHASE

Boy did i get a education on this one the other day.

2. Originally Posted by VTP99
Boy did i get a education on this one the other day.
Well, please share what you learned.

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Originally Posted by bunny
Well, please share what you learned.
Well he is still alive so I bet it was a valuable lesson.

4. Originally Posted by bunny
Well, please share what you learned.

5. Well for one thing don't just reverse any two phases to reverse direction. Also a fused disconnect is a no no with the N.E.C.

6. Originally Posted by itsiceman
A phase top
B phase bottom left
C phase bottom right

Yes that B phase is grounded and will read zero volts to ground but she is still HOT.

7. Originally Posted by thegoodlistener
Well he is still alive so I bet it was a valuable lesson.
Yes i'm still here but that 3 phase motor is toast.

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The voltage of a delta connected system from B phase to ground is actually 240V. The grounded or nuetral conductor is derived by grounding the midpoint of 2 windings. these systems are also referred to as Hi leg, Red leg, Wild leg etc. The reason is between 2 phases to ground the voltage is 120V , but the the third phase to ground it's 240V. There are a lot of these systems that are not marked. A clue is when you see a panel with every third space blank. In a 3 phase application they operate like any other 3 phase connected system. The NEC requires an overload protective device in every phase. That could be an overload heater in a motor starter, a fuse or a common trip circuit breaker. In NJ, PSEG has some delta systems in the older cities where 1 phase is insulated from ground, but the voltage between phases is 240V. PSEG also makes the hi leg phase C phase in the meter enclosure and we have to transpose that conductor from C phase in the meter enclosure to B phase in the panel as per NEC. These conductors and bus bars should be marked with orange tape, paint etc.

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## Correction

SBEC,
The type of service that you are referring to is a 4wire, mid point grounded Delta; VTP99 is describing a 3wire, corner grounded Delta. On this latter type, one phase is indeed grounded and is 0 volts to ground. However, the grounded phase is still current carrying just like a neutral is current carrying and is grounded. The drawing he attached is correct. This type of service is only found in commercial/industrial where there are only 3 phase loads.

A 4wire, mid point grounded Delta service is "hot" on all phases; 240v between all phases, and 208v to ground on the "stinger" or high phase.

10. J/D
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Well for one thing don't just reverse any two phases to reverse direction.
How do you change direction then? I have only seen this configuration once and had no problem changing direction. Dont understand how it would toast motor if proper voltage. Motor is still being energized on all three legs.

11. I have never seen it. Is this a regional thing?

I need to look into this.

12. J/D
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Originally Posted by zw17
I have never seen it. Is this a regional thing?

I need to look into this.
Just very old system not used in new construction the building I seen it in was pre WWII.

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