With 110v AC I seem to get about an inch away when the alarm starts, when sensitivity is turned up.

Better yet, Extech sells some where the probe is on a 3' insulated extendible stalk.

I probably shouldn't have mentioned it because it is way-out-there risky, certainly not anything I'd do except as last resort. But I have the tool and store it with the emergency gear, just in case...

PS. And, dead wires may not stay dead...