I recently purchased an older home (built in the 50's) and had a 200 Amp Panel installed with a Sub-Panel of 60 Amps to the garage. I am experiencing some lights that dim when the furnance, A/C unit, or power tools in the garage are turned on. Is their any reason why the lights would dim, especially when the furnace, A/C unit and the garage are all suplied by their own electrical circuits and breakers?
Just a guess but did you have your supply lines( pole to house ) replaced with a larger guage to handle the extra load. Your electric supplier can guide you with this.