I also agree with IanR:
The odd Voltage Readings on Phase "A" are result of a bad Termination in series with a connected Load.
The System described sounds like a normal 3 Phase 3 Wire Corner Grounded Delta, with Phase "B" as the System's Grounded Conductor.
Phase B is a Grounded Conductor, quite similar to other System Grounded Conductors; Bond it at one point only (such as the Service) to a Grounding Electrode System, plus a Main Bonding Jumper. Then bond all Equipment Grounding Conductors to the Grounded Conductor at the same spot where the the GES and MBJ are connected.
Identify the Phase B Grounded Conductor with White (or Gray) Coloring.
The differences between a Grounded "Neutral" Conductor and this "Grounded Phase B" are:
- Grounded "Neutral" Conductors are used on "Dual Voltage" Systems, across Multiwire Circuits.
- Grounded Conductors are part of a 2 Wire L-N, or 3 Phase 3 Wire L-L-L Circuit.
- The Phase B Grounded Conductor of a 3 Wire Grounded Delta is One of the Three Phases involved with a normal L-L-L 3 Phase Circuit, and this Circuit acts no different than any other 3 Phase 3 Wire Circuit.
Additional notes include:
Do not install Fuses in series with Phase B. If a device opens all 3 lines at the same time, Phase B may be run through Circuit Breakers and Disconnect Switches.
There is an allowance for final running protection of Motors to use single Overload Devices in series with the Phase B Grounded Conductor. This does not include the Disconnecting means at equipment.
Check out the Technical Reference section for Schematics of Delta Systems.
Good luck!
Scott
