powerplay
Senior Member
- Location
- In front of a computer.
I was looking at an old 100amp 240V meter on an 100A meter base feeding an disconnect switch, but discovered there were 3 fuses in the disconnect and no neutral....turns out that in the old days they used 2 pole transformers in a "Scott Delta" setup no longer available, to save money and achieve 3 phase power which was metered by a single phase meter with one leg run straight through to the disconnect.
I have taken readings to the bonded enclosure, and realize there is no real ground reference, but would like to understand how I got the readings I did...I have suggested installing a ground fault detection device, but have been informed that an old installation like this is an old "existing non-conforming" setup and does not need to be enforced.
Phase A - 93 volts
Phase B - 159
Phase C - 250 volts
...A and B connected to the old meter base probably causing those voltages ??
What maintenance usually is involved with this old system to ensure safety? ...I'm thinking of installing the Ground Fault Detection anyways. The panel feeds rooftop A/C and heating loads. The building also has grandfathered an second 120/240 volt service in a different room inside the building.
I don't usually work with a Delta system so I'm grabbing my old school books to learn more, but would appreciate feedback/info about this old system to further understand what to expect......any advice/great reference material ???
Thanks... "Back to School Sparky"
I have taken readings to the bonded enclosure, and realize there is no real ground reference, but would like to understand how I got the readings I did...I have suggested installing a ground fault detection device, but have been informed that an old installation like this is an old "existing non-conforming" setup and does not need to be enforced.
Phase A - 93 volts
Phase B - 159
Phase C - 250 volts
...A and B connected to the old meter base probably causing those voltages ??
What maintenance usually is involved with this old system to ensure safety? ...I'm thinking of installing the Ground Fault Detection anyways. The panel feeds rooftop A/C and heating loads. The building also has grandfathered an second 120/240 volt service in a different room inside the building.
I don't usually work with a Delta system so I'm grabbing my old school books to learn more, but would appreciate feedback/info about this old system to further understand what to expect......any advice/great reference material ???
Thanks... "Back to School Sparky"