DIYbanter - View Single Post

Dean Hoffman[_13_]

On 1/13/13 5:57 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. All the triplex I've ever seen is 3 wire, two
are insulated, one is bare. That's for a standard 240V single phase
system.

Im thinking that this cable was intended to be for three phase wiring.
Three hot, and the neutral. Is this right?
Maybe that building once had 3 phase service, or they just had that
cable on hand when they wired it, and used what they had...

Triplex to me means three wires, not four. I would call that wire
quad.
The bare wire would be for the equipment ground, not the neutral.
The neutral is current carrying and is supposed to be insulated.
There have been some code changes regarding single phase wiring in the
U.S. Electric stoves and clothes dryers are what I'm thinking of. It
was acceptable long ago to wire them with three wires. The equipment
ground and neutral were permitted to be combined. That is no longer
permitted in new wiring. The current carrying neutral and the normally
non current carrying equipment ground have to be separate.