Lights go dim with a moderate load imposed: how to troubleshoot?

Question

I just bought a house built in 1964 which features switches and outlets that have the "strip wire and insert into hole" connection method. In one of the rooms, turning on a ~500 watt load plugged into any outlet in the room causes the overhead light fixture to significantly dim, and a neon pilot light plugged into any of the other outlets in that room will either flicker or go out altogether.

I suspect one of the strip-and-insert junctions in that room has developed enough resistance to create a significant voltage drop when a load is imposed on that circuit. Other rooms served by the same circuit breaker in the central panel as this one do not have this problem to the same degree.

What is the process for systematically tracing this problem back to a specific junction point in the wiring to this room?

Answer 1

Poke in wire connections on switches and outlets are notoriously failure prone. Whilst it may be practical to troubleshoot and find the worst connection in your room causing the voltage drop be aware that this is a rather dangerous situation. Voltage drop in a connection with any significant amount of current flow will heat up the connection and can lead to burned insulation on the wires, melted wires and even can lead to fires.

The best recommendation in your situation would be to start replacing the various switches and outlets with ones that use screw terminals or screw clamp terminals. These components are really low cost compared the case when a failure results in a fire or extensive rework of existing circuits. Especially true when you now know you have a failure time bomb in this room.