Thanks Dan - electrical noise (I assume you mean line noise, typically from bad insulators or loose hardware on the poles) is the worst.
Many electrical utilities are responsive to noise complaints, especially if you can locate the source yourself and give them a pole number. Often it is not just one source.
A handheld scanner set to aviation band with the squelch open is a great tool for searching around. You might start in your car with the AM radio tuned to an open frequency (during the day is best). That will often get you in the region - and then you can go on foot to pinpoint it. If you have a small directional antenna that helps a lot - it does not have to be resonant in the aviation band since that can make the size a little unwieldy - but it should have some kind of directional pattern to it. Even a short dipole can be helpful.
Here is a product that I have found helpful on occasional, but you can certainly do this on your own with a handheld scanner:
http://www.universal-radio.com/CATALOG/meters/4030.htmlHope this helps.
Dave