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Starting from post #1. "Most wiring is 12-2 with no ground".
Suppose we have an unswitched neutral, then electrically the neutral is essentially at ground potential. The hot wire is switched, and there are two wires in the cable, a switched hot and neutral. This is not a three-way circuit. Any other hot wires are spaced somewhat more than the distance of hot to neutral in the cable of interest. Thus, the capacitance from some other adjacent hot to the switched hot of interest will be less than 20 pfd per foot.
With all loads on the switched circuit removed what is the high impedance voltage (10 megohms input impedance) from the off state switched hot to neutral? Same question but with the switched hot wire disconnected from the switch and measured from the hot wire, and separately from the switch terminal?
Assuming virtual no voltage from the switch terminal, then what is causing leakage to the floating hot wire?
Some readings on a Fluke 27 and Simpson 270 for different series capacitors. The Fluke input is 10 megohms with maybe 27 pfd shunt capacitance. The Simpson 270 was on the AC 250 V range and is 5000 ohm/volt or 1.25 megohms on this range.
pfd Fluke Simpson
0 4.8 0
100 42 7
200 68 13
300 83 15
400 92 25
500 100 29
600 104 34
1000 113 50
Source voltage was 123 V.
If in post #1 the CFL was not present, then the voltage read might imply a 200 pfd coupling if the leakage was capacitive.
From my previous experiment with capacitance in series with the CFL, if the leakage is from capacitance coupling, then a rather large capacitor is required relative to what can be expected from wiring. However, different CFLs might react with far less capacitance.
In a 3-way circuit with a three conductor cable and the switches in an off condition there is capacitive coupling of a hot wire to a floating wire. With newer Romex and thinner insulation, thus wires are closer together, the capacitance per foot may be somewhat greater than 20 pfd/ft, but not 10 times larger.
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