Quote Originally Posted by Bear View Post
They do need a grounded outlet to function in their intended capacity. If you "test" them simply by unplugging it from the wall, you'll no doubt be "failing" a number of otherwise working units.
The test units should be plugged into a dedicated (and grounded) socket which can be turned off at the breaker, leaving the unit with a ground contact
You lost me on that one. The only thing a backup needs a grounded plug for is surge protection. If you don't have it plugged into a grounded plug it has no where to shunt a surge and it looses it's effectiveness to protect electronics from any spike. It has no effect on the backup capabilities. UL requires that they have a bonding switch which acts as a ground. If it did not have a bonding switch (bonding relay) it would be of no use to me in any other type of application and most likely I'd be dead.