Review on Amprobe ST 102B Socket Tester GFCI by Chris Cooper

Firstly it works BUT even if the transmitter is bipolar and not polarized if the circuit is not grounded it cannot find the breaker in 80% of the cases. First check the socket with a tester. In addition, it only needs a light breeze to turn on the receiver's "ON" switch, then you need to press and hold it for 8-10 seconds to turn it off, or wait about 6 minutes. It's VERY important that you don't turn it on until you get it close to a working switch, as it has to "learn" the panel before it can find it.