what causes a ceiling fan light to blink

Question

I dropped a new romex line down through the wall to provide power to a flat panel tv mounted on the wall. The wall has K&T wiring in it. Everything seemed fine, until I noticed that the lights in a bedroom ceiling fan now blink. The fan is on the same K&T circuit as two wall sconces in the wall where I dropped the Romex cable. Did I damage the K&T wiring or is there some kind of current leakage or something else going on? How can I trouble shoot the situation?

Answer 1

It sounds like the K&T wiring definitely got compromised. A blinking light almost assuredly means that an intermittent connection or intermittent short has occurred. This could have been caused by some pressure or pulling exerted on the K&T wiring. It could also be due to some poor connections at or in a nearby electrical box getting jostled around.

In any case intermittent connections are something you do not want to have happening. The connecting and disconnecting of live circuits can lead to sparking which can cause a fire. An intermittent connection can also be a high resistance point in the circuit and cause the conductors to heat up and also lead to a fire.

Your immediately action should be to cut off any fuses or circuit breakers to the disturbed circuits. In my estimation your next course of action should be to fully replace the K&T wiring in at least the affected circuit area.

If your installation has the following types of things going on you should be greatly concerned.

Frayed Insulation

Non-Boxed Junctions

Dust and Insulation Covered Wires

Free Range Romex Connections

If your decision is to not heed the replacement advice above then your trouble shooting can start with opening all the electrical boxes on the affected circuit and check that all connections are good. Once that is achieved then you have no choice but to start opening up walls to trace the K&T wiring and look for where something has gone wrong. Pray tell that you do not find some in wall splice of the wiring that was done outside an electrical box that has now become a poor connection. Note that if you have progressed this far it is probably a wise choice to reconsider the replacement suggestion.