05/29/2026
This was a good one.
Got called out to a rental property for flickering lights and to replace a thermostat.
The thermostat was in rough shape, so I replaced it as requested. After the replacement, I noticed the furnace still wasn't working and found a failed transformer. Replaced the transformer, and the furnace fired right up.
The lights were still flickering, though. I checked the electrical panel multiple times, and everything looked normal. Finally, one of the times I checked it, I caught the problem: one leg was around 100 volts to neutral and the other was around 140 volts to neutral.
The property had an overhead service, so ComEd was called. They found and repaired a bad neutral connection on their end, and everything returned to normal.