We've lived in a home for 20 years that was built in 1970. It has
aluminum wiring. Over the years we have a consistent problem with a
kitchen light in the middle of the ceiling browning out after we turn
it on. It turns on just fine and a few seconds later it dims and then
goes back to full light. It might never do it again or it might repeat
this. We've been unable to establish a pattern.

We've been all over the house and exterior trying to tie that
particular behavior with appliances turning on or off, the washer
changing cycles or something and can't. We've had three separate
electricians try to diagnose and fix the problem but they keep trying
to say that it's a general brownout of the neighborhood when it clearly
is not.

We've changed the switches in the kitchen and elsewhere and "pigtailed"
the switches. I'm imagining that if there were a danger of fire we
would have had one by now so I'm assuming this is not a clearly unsafe
condition. One neighbor suggested that if there one non-aluminum line
on a circuit that this might be the source. Someone had added some
wiring before we bought the house. Does this make any sense or can you
suggest another direction to look?