On Fri,9/12/2014 5:42 PM, Gary Schafer wrote:
The whole purpose of the 4 wire system is to keep neutral current off of the
ground wire.
Right.
With a 3 wire system, if the neutral/ground should open there could be 120
volts on cabinets that are connected to the green wire ground.
Neutral and ground are separate conductors. They are bonded together at
the service entrance, but they remain separate after that.
There will also be a voltage difference between grounds due to voltage drop
on the common neutral/ground.
So what? By your logic, the power company would have to bring us four
conductors. They do not -- they give us two hots and a neutral, which is
the transformer center-tap.
As to bonding a tower to premises grounds -- if the tower is close to
the house, certainly yes. If it is distant from the house, it can cause
as many problems as it solves. Remember that lightning is an RF event,
not a DC event. Remember also that coax shield is properly bonded to the
tower top and bottom.And remember that the impedance between the tower
and the shack is dominated by the inductance, not the resistance.
And if you re-read my description, you'll see that everything in both of
my buildings are, indeed, bonded not only per code, but far more
robustly than code.
73, Jim K9YC
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