What can cause lights to dim?
I installed a sub-panel in my basement with about 12 circuits, two of them are 15A circuits for kitchen lights, and a 20A circuit for waste disposal. The WD unit is a 3/4hp Insinkerator. When I turn on the WD the lights dim for a few seconds and then return to normal. My understanding is that this is usually caused by a voltage drop, but I am note sure where that could be happening. The light circuits are 14/2 from panel to 3-way switches (about 15 ft) then 14/3 to a set of dimmer switches (another 15 ft) and then maybe 30ft total of 14/2 to individual light. The sub-panel is supplied by three 3awg copper conductors about 20 ft from the main panel. I am not sure if any of this would explain the dimming lights, and I am not sure what is feeding the main panel - from the ground they look like very thin wires (they look thinner than 3awg), about 70 ft to a pole, but the mast looks relatively new, so it seems unlikely that the supply conductors are under-sized.
Any ideas what might be the cause - could it be the lighting circuit run is too long? Could the dimmer switchs be the cause, somehow creating a voltage drop? Should I get the utility company to take a look at the supply?
Thanks in advance for your opinion on this.