I'm finishing my basement and have many existing splices of 18 gauge (2 wire) for thermostats and the alarm system and central vac. I'll run new wire where I can but it's not an option for many unfortunately. I'm trying to avoid my ceilings and walls being splattered with white plate covers all over. I know that Tyco had special connectors for splices of 12/2 romex cable which could be concealed behind drywall (meeting NEC 334.40(B)), but I'm having a hard time finding something equivalent for 18 gauge low voltage wire. Does anyone know of any? Or know of a way to do it that would be compliant (maybe butt splices and heat shrink tubing)? I'm in Massachusetts.