I own an old Tasco version of the Greenlee that came out with just after they got hold the design. It can trace most live or dead concealed wiring and I can usually find buried boxes with it. It can also be used for phase identification or to locate a circuit breaker or fuse in a remote sub panel.
A company I used to work for had the newer Greenlee tracer kit. I think they messed it up when they changed to automatic gain instead of allowing the user to manually adjust it as needed like on the older version. Another company I worked for had the newer Amprobe kit. It seemed much more complex and difficult to use than the Greenlee and the first time I used it I was completely overwhelmed and unable to use it effectively. After a little practice though, I was able to use it reliably and I think that now it is probably the better and more versatile of the two tracers. Expensive, but it can be easily justified the first time you find that box the “wallboard installation technicians” buried under double 5/8” and plaster skin coat.
