there are two switches in the box. One goes to an inside light the other goes to an outside light. i turn off the breaker and both lights go out. when I check with my voltage checker, I don't see anything on the outside light switch but it does light up off and on when I check the inside light switch in the box. each of these lights are only controlled by one switch. any suggestion?
A simple non contact voltage tester will detect voltage on a deenergized circuit when another live cable is in close contact, the way non contact sensors work is using the Hall effect. You can prove a similar function by standing under a power line and raising a fluorescent lamp above your head, wow the light glows, not full power but it glows, Hall effect sensors work the same way, you may have a hot wire in close proximity to one that is turned off and well guess what it lights up because of inductive coupling ( this is how transformers work) so yes your tic tester or non contact tester may light up on a dead circuit that is in close proximity to a live circuit. Turn your main breaker off and there will be no voltage unless you live close to a radio station.