Doing the electrical for a friend on his 1000 sq ft addition. Main part of the house has an existing 10 yr old 200 amp panel that is full. I was going to put a sub panel in the new addition utility room and either back feed it or just get a panel with a 100 amp main. Can I use a 100 amp breaker in the existing panel and feed the new sub panel with a 100 amp breaker or does this violate the tap rules its about a 50-75 ft run from panel to panel ?
