corner grounded delta troubleshooting

[jim dungar]

Thank you. I have never personally ran into such a set up in the field. Rarely a high leg delta do I see.

We are discussing corner-grounded deltas, not high leg (center tapped) deltas.

But I’m curious even in the main/service disconnect can the grounded conductor be ran through the breaker? Or what is a typical installation?

Per the NEC, the grounded conductor is supposed to be white. Old installations tended to ignore this requirement. The NEC allows switched grounded conductors.

It looks really strange to have a white conductor run to a breaker. My experience has been when following the NEC colors most installations use 2-pole breakers likewise, when following more typical colors 3-pole breakers are common.

 

[ptonsparky]

It looks no stranger than having a white run to a motor starter and having an overload in that line as well.

 

[kwired]

Is it typical for a 3-phase panel to be used with a corner grounded delta then the grounded phase has an OCPD in it?
240.22 (1) allows it. I would be inclined to use a single phase panel and land C-phase on the neutral bar.
Thats also interesting its a utility service, I have only encoutnered it in plants with customer owned transformers.
Make sure the grounded C-phase to all the minisplits white or gray, unless they allow Blue by special permission.

I never seen a utility supplied 240 volt corner ground, 480 volt corner ground used to be pretty common from utiliy and some are still around here.

Can't recall seeing a new corner ground put into service during my time in the trade though. Many high leg deltas out there, most are 240 volt but is common with open delta even at 480 volts.

 

[tortuga]

We are discussing corner-grounded deltas, not high leg (center tapped) deltas.

Per the NEC, the grounded conductor is supposed to be white. Old installations tended to ignore this requirement.

Its a common international standard to use blue for the grounded conductor of a 240V system anyway and if one had a corner grounded 240 delta along with a 208/120 and or 480/277 in the same facility I could a good argument to use 'special permission' to have the blue grounded conductor so no other neutrals got mixed up with such a system.

 

[ptonsparky]

I never seen a utility supplied 240 volt corner ground, 480 volt corner ground used to be pretty common from utiliy and some are still around here.

Can't recall seeing a new corner ground put into service during my time in the trade though. Many high leg deltas out there, most are 240 volt but is common with open delta even at 480 volts.

A 480 corner ground was the only new one I installed. Mid 80's. Had one other that had been around since the late 50's.
240 volt were on wells in the Platte River Valley. 15 - 30 hp. Guessing they had been there since the 50s.