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Joseph Meehan wrote:
wrote:
This is perhaps a safety question. Most of the disconnects to 220v
appliances are two hots plus ground (I have an air conditioning
compressor, a well pump, and an accessory heater wired this way) with
no neutral wire. The neutral isn't "necessary" as each hot is 180
degrees out of phase negating the need for a separate neutral.

But doesn't this mean if there is a short the appliance case AND the
separate disconnect box (if metal) are BOTH electrified since their
grounds are connected and there is rarely if ever a separate
ground-to-earth at the appliance?

Unless there is a failure of the ground wire the short to the
appliance
case be a short to ground and the breaker will kill the circuit and both
legs will be cut if it was properly connected to begin with.


Exactly what I was thinking. How people can be saying that the
appliance and the disconnect case will both be hot at 240V is beyond
me.

I don't think anyone was saying there would be 240v, just possibly 120v.
If the ground was broken and there was a short, then there would be 120v at
the box connected to the broken ground; further assuming nothing had good
enough contact to ground to trip the breaker.
It is not the type of thing anyone should lose sleep over, but it is
possible.