Hire a pro to diagnose anything you're unsure about, but here's how to wire a 3-way switch with power coming to the switch first. Test your non-contact voltage tester on a known live circuit to ...

Add/Relocate 3 Way Switch without Rewiring - Simply wired between the power and lighting fixtures; no complex in-wall rewiring or WiFi needed to add/relocate switch, pre-programmed for immediate use.