I need to rewire my home. When it comes to dedicated circuits I am a little lacking in education. I realize all 240 lines must be that way, as well as bathroom circuits, and microwave. My question is dishwashers, disposals, and gas furnace ( all soon to be using using 12 ga wire ). I would love to branch off the furnace circuit to power a 100 watt light bulb to my bench (thus giving me at least one light in my basement on different circuit). Also can I pair up my dishwasher and disposal? I do not have much room in my box, actually the former owner doubled up on breakers. I am thinking about upgrading from the 100 amp to a 200 amp service just to have some breathing room. Besides from what I hear the federal pacific box is a fire hazard anyways.
One more question, from watts what number do you divide by to get total amps in a circuit..110-115 or 120? Thank you for your help. john