That incorrect wiring, as plotted, doesn't increase the residual current even one mA. There has to be something else.
At the time (1985), there were no electronic switched loads in the network. Microwaves were barely just starting, no PC boom yet.
This make no sense, the GFCI doesn't care about the ground wire, it measures the difference in current between the 2 supply wires.
Look up a datasheet for the LM1851 IC, it will show sample circuits for a GFCI, there's no connection to the ground wire at all. In fact you can use a GFCI on an ungrounded circuit and it's still functional.
I may be confused. What do you mean by protector?
That's almost exactly backwards, in practice.
When the system is in use (that is, when the Hot line is drawing current), the Neutral and Ground wires are at the same potential
*ONLY* at points where they are actually bonded together - that is, at the panel or sub-panel or transformer.At other points (for example, at the outlet) they won't be at the same potential. They can't be, because the neutral wire is carrying current and has non-zero resistance, and thus has a significant voltage drop between the outlet and the panel. The protective-ground wire won't be carrying current, and thus has no voltage drop between the outlet and the panel.
So, if a GFI considered "ground and neutral wires are not at equal potential" to be a fault condition, it would trip every time somebody turned on a light or appliance.
If you want to see this demonstrated, it's not difficult to do, if you have an AC voltmeter with properly-shrouded insulated test leads. Using one half of a standard outlet, measure the voltage between the neutral and ground contacts. If nothing on that circuit is drawing current, it should read 0 volts, or within noise-factor of that.
Then, plug a 15-amp space heater into the other half of that outlet, and turn it on. You'll almost certainly see a significant voltage develop between ground and neutral, caused by the current flowing from the outlet back to the panel through the neutral wire. I'd expect something on the order of a volt or so to show up on the meter.
If you don't see a voltage drop between ground and neutral under these conditions, it may very well mean that your outlet is mis-wired, and has ground and neutral connected together at the outlet... which is a definite no-no.
Look up a datasheet for the LM1851 IC, it will show sample circuits for a GFCI, there's no connection to the ground wire at all. In fact you can use a GFCI on an ungrounded circuit and it's still functional.
In other words I agree if the ground & neutral being at differing potentials matters then there's some sort of leakage and the GFCI should trip.
Jerry
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