Buy one with a continuity tester. The Ideal VolCons are the one that I use and recommend. I have an old Wiggy too, but since it does not measure continuity, it is practically useless.
I have both of the VolCons, the old-fashioned solenoidal type and the newer digital VolCon Elite that Doug mentioned.
A few things to remember. The VolCon Elite is high-impedance, so it will not trip a GFCI, if you happen to try to use it for that purpose. The old fashioned solenoidal type "Wiggies" are low impedance, and will trip a GFCI, and also are not as susceptible to ghost/induced voltages.
Peter
