> I know you can't tell them anything but have had very similar problem
> of high voltage when the ground connection is loose, one time behind
> my electric meter and once on the transformer on the pole and the
> third time (different location) was also the ground connector at the
> hogshead above the meter. The general linemen don't seem to
> understand why a loose ground and a heavy load on one side of the 120
> would pull it down (pulling the poorly connected neutral toward the
> load) and causing the opposite leg to INCREASE in voltage.
At least he can be sure his neutral is good because his 240 line
was balanced.
Measuring voltage between the power line neutral and a local
ground is not an indicator of a problem, as long as that voltage is
fairly low. Some voltage is normal from the mains ground to other
grounds, but not over a volt or two normally. There are exceptions
where it can be higher and still be safe, and the line not have a
problem.
In remote areas the neutral lead is often very long, and of course
any conductor has voltage drop along it. In a single phase system,
the neutral carries the same current as the primary wire. In a multi-
phase system, it carries the unbalanced current from the phases.
Because of that, it is normal to see some voltage between the
neutral and other grounds.
I'm about 10 miles from the sub-station and on a single phase line,
and I consider that an extreme. The line I am on has .2 ohms per
thousand feet. That's about 11 ohms.
If the primary current is only 10 amperes for me and the houses at
this end of the line, there is 110 volts of drop between the
substation ground and the neutral outside my house.
I have measured about 4 volts between my radial systems and the
power line ground (measured on a high impedance meter), even
though the line is perfectly fine. It is the grounds at other house,
and occasionally along poles, that reduces the available 110 volts
to 4 volts of actual voltage. Picture the earth as a giant voltage
divider, and I am tapped across only part of the normal neutral
drop.
Of course if I measure AC current it is very low.
If they had an open neutral on the primary, I would likely have
several hundreds of volts and a dozen amperes of current into my
ground system!
I bond the power line ground to the feedline shields (that connect to
the radial system) with 3" wide flashing.
This is a good example of why ALL grounds should be bonded
together outside the building at the service entrance. The feedlines,
the tower, the CATV line, and the telco safety ground should ALL
be connected at the entrance point to the house. It's not only better
for lightning, it's a good safety idea for power line problems.
73, Tom W8JI
W8JI@contesting.com
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