Heads up on a weird battery drain issue I ran into in an old building

I was doing a panel swap in a 1920s apartment block downtown, putting in a new wireless system. Everything tested fine, but the keypad batteries were dead within two weeks. I went back three times, checked for signal interference, the whole deal. Finally, I pulled the old baseboard heater cover near the main panel and found a huge bundle of old, unshielded knob and tube wiring still live and running right behind the wall where the keypad was mounted. The electromagnetic field from that mess was just cooking the batteries. The super had no idea it was even there. Has anyone else had a piece of old building infrastructure completely tank a new install like that? What did you do?

3 comments

3 Comments

grantnelson15d ago

Ever try a ferrite bead on the keypad's power wire? That plus a thin sheet of aluminum behind the unit as a shield finally fixed it for me.

victor65115d ago

My own fix was way less clever. Kevinallen is right about the shield, but I just wrapped the whole thing in foil like a baked potato. Looked stupid but it worked.

kevinallen15d ago

That aluminum shield idea is smart.