Electrical – Separate circuit, but why is the disposal causing lights to flicker

electricalelectrical-panel

My garbage disposal was on the same overloaded circuit with many other items in my 1949 home. Lights would flicker when the disposal would come on. These were all on the same circuit.

I recently ran a new circuit for my disposal (had electrician do the panel work). Strange thing is that the lights on the old circuit, that the disposal was on, will still flicker when the disposal comes on.

The age old question, any guesses on what could be causing this flicker when the disposal is on its own circuit? Could it be that a wire is loose on the light's circuit in the panel?

Clarification: They do not flicker but instead dim briefly when the disposal first starts up. Sorry, I used the wrong words.

Best Answer

  1. If the light does flicker also if a hairdryer or vacuum cleaner is connected to the same outlet/box as the garbage disposal, it is likely a problem upstream the location where both circuits (light, garbage disposal) are connected. A loose connection acts as voltage divider in combination with the garbage disposal or any other big load. F.e. backstab connections are known for problems.
  2. If the light does not flicker if the garbage disposal is replaced by a hair dryer or vacuum, it could mean that the garbage disposal motor emits some energy, e.g. HF or inductive surges, that disturb other electronic devices nearby. Maybe the motor capacitor has gone bad or the graphite elements/sliding contacts are worn out.

In both cases the motor should have less power compared to an installation without any problem.

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