corner ground delta

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kenkratz

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I have a job that has a corner ground delta system . It is servicing a multiple meter set up. I attempted to check ground to neutral continuity at one of the panels and it did not exist. I checked main bond jumper and it was installed. Is this lack of continuity a function of the corner grounded delta system, or do I need to look deeper for a broken connection.
 
First, do you have terminology and understanding of this system correct?

Corner grounded delta has no "neutral", it has a "grounded conductor". That grounded conductor must still be bonded at the service equipment and run a separate "equipment grounding conductor" with the branch circuits and feeders.

You are permitted to switch the grounded conductor - if it is simultaneously switched with ungrounded conductors. A three pole breaker can be used for this, or even three pole motor controllers or other similar applications and if you have that switch/breaker/contactor open you shouldn't have continuity downstream between the grounded and grounding conductors.
 
I am unsure if my terminology is correct. I have a three phase service that has a high leg. There is a neutral present as well. Is this a corner ground delta system
 
No, it is not corner grounded, it would be a center grounded Delta meaning one winding is tapped and grounded at the center, the same as a single phase transformer would be.

Roger
 
kenkratz said:
I have a job that has a corner ground delta system . It is servicing a multiple meter set up. I attempted to check ground to neutral continuity at one of the panels and it did not exist. I checked main bond jumper and it was installed. Is this lack of continuity a function of the corner grounded delta system, or do I need to look deeper for a broken connection.
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If the red and blue sentences apply to the same enclosure then you have almost certainly misdescribed or misidentified or mismeasured something. By definition, if a main bonding jumper is installed then you have ground to neutral continuity at the point where it's installed.

If the red and blue sentences apply to different enclosures, then you may have a broken or missing connection in between the two enclosures.

The above is true regardless of system type and whether the white conductor is a grounded neutral or merely a grounded conductor. Sounds like you have what I see most often described as a high-leg-delta system. If the ungrounded legs are 240V to each other, the neutral will be 120V to two legs and 280V to the high-leg. The same voltages (or very close) will be true from hots to ground if the neutral is properly grounded.
 
I used the term corner grounded delta after contacting someone for info. After your input I did a little research and realized I was misinformed by my original contact. It is a high leg system. I am confident of my continuity check, and I will investigate more. I appreciate your advice.
 
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