Hello,

I live in a home built in the 40's. It has the old cloth covered wiring, new panel and breakers (6 years old). I have one circuit (which is very much overloaded) that never had a problem before (as long as the blow dryer wasn't on with anything else). I recently replaced a switch in the hallway because the old switch was too loose. When I did this the insulation on the wiring was cracked in a few places (I taped it). Now that the new switch is in I'm getting EXTREME dimming from all of the lights on this circuit. The connenction at the new switch is firmly in place. Any ideas?

You may have disturbed a splice in the switch box you worked in.

I have found even a soldered splice to break enough to create a loose spliced connection.

Your best bet is too pull out the splices and re-do them.

This will be tricky as you already have cracking insulation. While taping is OK, if you find or cause more damage, you may want to consider using heat shrink tubing to re-insulate the wires.

I checked all the other connections in the box and everything is firmly in place. I re-insulated the wires with shrink tubing. Attached everything, still had dimming.

I then removed the new switch and just capped the wires. Turned the circuit back on, and now no dimming. Could it just be a bad switch? I have to run to the Depot to get a new switch as that was the last one in the pack (I'm replacing all of the old devices).

Sounds like bad switch. If you can get new circuit to Hair Dryer, would be a good idea.