"Doug Miller" wrote in message
t...
In article , Nate Nagel
wrote:

but the receptacles installed on the first and second floor are
grounding type and it appears that the ground is provided by a jumper at
each receptacle between the ground terminal and the neutral. I realize
that *theoretically* this is functionally identical,

No, it isn't, not even theoretically. This makes it possible for the
chassis
of any piece of equipment plugged into the outlet to become electrically
live,
and it's not at all safe.

If the two wire circuit (w/o ground) is protected by a GFCI, it's quite
safe. Under some circumstances it is more safe than a grounded outlet
without a GFCI.

If you have an old house replacing behind the wall wiring just to get
"grounds" isn't necessary. If you are knocking out walls and/or adding new
circuits you new wiring should meet code but so long as you have GFCI
protection, there is no reason to fear for your safety with old wiring w/o
ground. BUT you should "test" your GFCI using the build in test button.
An external GFCI tester will not trip an ungrounded GFCI outlet.