Here is a review left by a customer on a product. Would you say he was satisfied or dissatisfied?
Title: Amprobe AT-1000
Review: Very disappointed in this device. Tried to find wire routing in the wall but found that it was almost impossible. With the transmitter plugged into a wall outlet using the included plug, I could follow the romex in the wall only a few feet from the transmitter, even at max sensitivity on the receiver. Finding a different return path for the signal, like a water pipe, was not really practical--no pipes were anywhere near the circuit I needed to trace. I did as well with a cheap unit that cost 1/10 the price of the AT-1000. Note also that if there is a light with a dimmer control connected a circuit anywhere near the one you are trying to locate, the noise generated by the dimmer (if lamp is on) swamps everything. One positive note about this unit is that it does come in a nice case.
