+1... 45V feeding a 100W light bulb, is different than 45V reading on a high impedance voltmeter.
But both are wrong.
JR
+2... These so called "phantom" voltages are typically capacitively coupled by proximity to live wires, thus creating a high-pass crossover circuit of sorts. That's why these phantom voltages often sound like a high-frequency buzz rather than a low-frequency hum. If it was a solid connection there would be hum and a lot more current carrying ability. But this undesired capacitor coupling doesn't let the bass (60 Hz) through, only the higher harmonics.
You get the same sort of effect when you have an open leg on a mic line. You'll probably notice that the signal level will drop way down, and all that's left is high frequencies. That's because there's capacitive coupling of the broken leg wire to the shield which creates a high-pass filter tilt on the signal coming into the balanced input.