Howard,

A wye connection is BY DEFINITION grounded through the fourth wire. The wires
leaving that bar can be either grounded conductors (neutrals) colored white or
equipment grounding conductors, bare or green. Because you measure 277 V between
each line and ground, it would seem that you do have a wye connection on the
secondary (building) side of the utility transformer that supplies the building.
Yes, you will need to run both a neutral wire and a ground wire from the
inverter to the ground bar at the main panel. At the main panel the neutral and
grounding conductors are bonded on the bar directly bolted to the metal
enclosure. The white taped wire at the service head is the neutral, more
properly called the grounded conductor. It is connected to earth (ground) both
at the base of the utility pole and at your building through the grounding
electrode conductor. I don't know of another way to obtain these voltages. In my
experience this is how it is typically done. It is a very common three phase
service connection. The grounding electrode conductor should be found in the
main service enclosure or at the utility meter.

Dick Ratico
Solarwind Electric






--- You wrote:
-          Is it possible to have an ungrounded Wye where the "4th wire"
actually is a neutral to the lower right bus bar, and the wires leaving that
bar are in fact ground wires?

-          The SE10K calls for a neutral wire in a Wye config.  If this 4th
wire is a neutral, and is bonded to ground, can I run a wire from this to
the inverter neutral, then another wire from this same bar t0 other ground
wire location in the SE10K (right beside the neutral).

-          Is the white taped wire (the bare wire from the pole, then
insulated and taped white into the service head) a neutral or is that
ground.

-          Can anything other than a 480 Wye give the 480/277 voltages
indicated above?

-          If the 4th wire is a neutral (I certainly hope it is), where
might I find the ground electrode conductor (the building is relatively new,
less than 10 years I believe.).  FYI, the building is metal.
--- end of quote ---

