I may be dumb as a pile of rocks,,but if on a 2 wire system and a ground fault outlet and I stick my handy dandy tester in it and I see the center light come on (ungrounded??) I then press my super handy dandy tester button and nothing happens, then the outlet is not working proper for gfci??? My question is will a tester trip a GFCI on a 2 wire system. Jim I know that that this is small stuff for you along with many others,,however I may have been sleeping during this part.