Fred Bucheit claims that thousands of lives would have
been saved over the years if the power company had not
chosen to ground one of the transmission wires.
I think it is difficult to know if that is true.
One thing we gain by grounding one of two wires is
predictability. If the power company did not ground
one of the wires, who is to say that your neighbor
won't ground one of them. What happens when a device
(like a clothes washer) goes defective and one of the
wires makes electrical contact with the case?
If you assume neither wire is grounded, and therefore
there is no danger to touch either wire plus ground,
you are in big trouble if the other wire has become
grounded either accidentally or intentionally by
someone in your neighborhood.
I think the predictability of the grounded system
probably makes it safer than the ungrounded system.
Above is historical. Today the distribution from the
power company (or substation) is 3-phase, at least
until it gets to the local residential neighborhood.
In the 3-phase system the transformers can be hooked
up as 3-phase wye or 3-phase delta. The delta
configuration does not have a neutral/ground.
In places where 3-phase delta is used, we lose some
of the predictability. This is not seen in residential
systems, but can be present in some industrial settings.
Fred mentioned isolation transformers. Isolation
transformers are good, and I trust them on a local
level where I can see the wiring. However, as soon
as someone grounds a component on the "safe" side of
an isolation transformer, the protection is lost.
I do not trust people in the next room, let alone
those down the street.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu