I got one of those testers back in 2001 and used it all the time. Later the testers and the testing of the devices was talked about at one of the state IAEI meetings in 02 or 03 ?. What I remember was that the only way to actually test the arc-fault device was to use the test button on the device itself. The button on the hand held tester was not doing something and was not being concidered good enough. I still use the testers other functions.