Yes. With an EGC, equipment that develops an internal ground fault
(e.g. to the chassis) will trip the breaker. With a GFI only, the
equipment chassis will remain hot until someone comes along and
provides a path ground to trip the GFI.
Also, redundancy usually improves safety. GFIs fail alot more often
than the EGC.
Because GFI's have to do something, something mechanical I think, for
them to work.
The equipment ground is just a wire connected to the chassis. It's
there all the time.
Also, who can be sure that one will always use any electrical device
from the same outlet all the time? (unless it's a furnace or water
heater, or ok, ok.... These aren't GFI outlets anyhow, iiuc.)
Appreciate the multiple purposes of that wall receptacle ground. An
obvious and original purpose is to short out a circuit that would
otherwise cause human electrocution. This is essential for appliances
that have exposed conductive (metal) parts. GFCI (that has not been
damaged by surges) also does same function.
Interconnected electronics also need (should have) a common ground
connection. Again, the equipment ground accomplishes that so that
voltages between appliances do rise above 30 volts and so that AC
leakage has a path to bleed off to.
Two reasons provided.
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