It's pretty common for the inrush current of motors to dim lights; most residential Xformers are about 25KVa (Good for about 104 Amps at 240V) and split between 2 to 4 200A services. It's easy to imagine that even under diversified loads, peak times could test the Xformer's ability to provide steady voltage.
If #14 was predominantly used and used in long homeruns, then voltage drop would be aggravating a poor situation.
I think Scott35 refers to this phenomenon as Flicker factor
[This message has been edited by sparky66wv (edited 05-31-2001).]