On Jan 13, 6:57*am, wrote:
A large store downtown has a heavy FOUR wire triplex feeding the
building. *3 wires are black insulated, the other is the bare neutral.

The thing that caught my attention to it, is that the 4th wire is not
connected to anything.

If it's not connected to anything, why are you identifying it
as the neutral? You have 3 wires that are apparently
current carrying conductors and one that is bare, not
connected. Assuming this is overhead, ie going from the
pole to the building, sounds like the bare wire is for
support only and you have a 240V service, with two
hots, one neutral.