A transformer has malfunctioned, but following wiring visually from switch to where it "disappears" behind base cabinet, we can't tell where transformer is. There is a granite slab backsplash between base and wall cabinet. Without disassembling entire kitchen, is there a way to find out where transformer is or how far from switch?

I remember decade ago a tool we used when wiring commercial properties to determine where a break would be, but can't remember what it was called.

Thanks for any help.