I gave your theory some thought and I can see where there would be an increase of current on the equipment grounding conductor as more leakage was present but I cannot see where the voltage would increase. If anything the voltage would decrease. Wouldn’t more leakage translate into a lower neutral to equipment ground resistance? The lower the resistance, the higher the current, the lower the voltage. Extreme example. 0 ohm resistance between the neutral and equipment grounding conductor.Hi Jim,
With hot and neutral reversed and a component turned off 120 volts will be applied to the end of the primary winding of the power transformer in the component which normally receives AC neutral. AC neutral presumably goes nowhere in the component in that situation (other than perhaps to a line filter capacitor), assuming the component doesn’t have a standby mode or is not in standby mode, because its power switch is turned off. The 120 volts will leak to some degree to the chassis/AC safety ground of the component via stray capacitance in the transformer. That degree being different and I would imagine probably greater (perhaps much greater) than under normal circumstances when 120 volts is applied to the other end of the transformer via the power switch. So what I’m envisioning is that the reversal of hot and neutral will result in a significant voltage being applied to the safety ground, resulting in significant current through the safety ground wiring while no current exists in the neutral wiring, resulting in a significant voltage developing between safety ground and neutral as a result of that leakage.
I could be wrong about that, and admittedly creation of a 4 volt difference would seem to require a great deal of current. But nevertheless it seems to me to be a possible explanation. And as I said, if that is the main contributor to the 4 volts the issue will go away when hot and neutral are connected properly, without the need for further corrective action involving the wiring and connections.