Greg, I couldn't even guess how much coupling we might get. Experience in the field has probably been in the 100s of mV to couple volt range. But coupling would be intuitively greater with the switch on and running the whole distance back to the open beaker at the panel, At any rate, you wouldn't expect a change when he opened the feeder breaker if the switch looked infinately open. Plus, you gotta admit that a switch that looks like 70M when it's open, is a pretty good switch.
If you're talking about the 8060 with the buttons down the left side and dB capable, I love it. The only thing I like better on my 187, is being able to capture SCADA burst amplitudes by using the min/max record function. At least we can externally lower our input z on hi-z meters and it's a lot harder to go the other way.
Joe
