"ml" PREVIOUSLY wrote in message
...

14story building i am on 4thfl

"ml" wrote in message
...

soon to put a antenna on my roof (12floors high) i naturally wanted to
put a ground or static discharge up there

m

Since you're still serious about this, if possibly from a lower floor....

The waste-vents, if cast iron, will have steel pipe hangers clamped to the
building's structural steel at every floor, with the first one being right
under the roof. It might very well be an excellent static ground. Without
meggering the vent, you could still determine DC resistance by running an
extension cord from the rooftop utility room outlet to a vent pipe, and
measure resistance between the electrical ground and the vent.

Jack Painter
Virginia Beach, Virginia