Tom, the bit about cutting the ears off the plug means that the plug could
then be plugged in backwards. Thus, the neutral wire of the appliance is
connected to the hot wire instead. And you're right, once in a while an
outlet gets wired backwards which causes the same result.
In the case of the open neutral, no, Tom, that doesn't make the ground hot.
The ground is still connected to water pipes, ground rods, or whatever was
used as the grounding electrode (the code specifies several acceptable
ones). Ground is still therefore ground.
If the power transformer center tap at the pole opens, the house neutral
becomes the reference, and if the load is not balanced, the two 120 volt
lines will become unbalanced and can burn out light bulbs, computers, or ham
gear (Gadzooks!) but it does not cause the ground to go high.
To explain why the equipment grounding conductor (safety ground) is
connected to the grounded conductor (neutral) at the panel only: The safety
ground has two purposes: first, no matter what fails in the system,
equipment cabinets or exposed grounded parts are grounded and won't rise to
an unsafe voltage; second, the equipment grounding conductor provides a path
for fault current. Suppose that the hot wire in your old metal case
electric drill becomes frayed and shorts to the case. Since there's no
ground wire, the short doesn't trip the breaker. But if there is a
grounding conductor, the breaker trips and both shock and fire hazards are
removed.
This has been a bit lengthy, but our safety is involved. Hope it has been
interesting and helpful to all.
73
Larry, N9DX
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