Question about small voltage between neutral and ground
I have a 15A circuit that powers one outlet and 4 basic light bulb fixtures in my unfinished basement. I just added the 4th light fixture today. The outlet is always powered while the lights are controlled by a switch (which is nothing unusual :-)
I usually sanity check my work before putting covers on lights and outlets by measuring the voltage across the hot and neutral wires and also by doing a quick continuity check with my voltmeter between the neutral and ground wires (by usually, I mean the 3 or 4 times I've done minor wiring projects at home before). Since neutral and ground are at the same potential, I expect to get a steady beep with my meter (i.e. essentially no resistance). When I test this specific circuit, I am getting an intermittent beep rather than the typical continuous one. I measured the voltage across the ground and neutral wires and got a couple of hundred mV. I realize that is not much, but it surprised me as it is higher than what I would expect to see.
With the switch off, I can get the steady beep at the outlet, but as soon as I switch the lights on, the continuity test starts beeping intermittently at that outlet.
I doubt this is a cause for huge concern, but I am confused as to why this is different from what I've seen before.
Any thoughts as to why this is happening? Does anyone else do these types of continuity checks to test the ground and neutral connections?