Jeff, Picked up a "Techni-Tool" catalog #56 [Plymouth Meeting, PA (610) 941-2400] and they list a Extech DMM (catalog number 355TE289 at $199) with a clamp-on current probe (catalog number 355TE945 at $149) that has a resolution of 1ma AC - also measures DC (muust be hall effect!). I bet you could check current by just clamping the unit around the glass (midpoint - for safety) - wouldn't even have to open the can! Regards, Telford Dorr