not a real electrician, just a lowly part time contractor and am quoting a basement finishing job. the home is about 2400 sq ft with central air and is about 10 years old, it has a 100 amp panel with a few double throw breakers already added for previous work where there wasn't any more room for aditional single breakers, now i will hire an electrician to pull permits and do this right, but for quoting purposes is it required to upgrade to a 200 amp service panel or is accepable to add a small 4 circuit sub panel, i don't think that will pass figuring 2400*3\120=60 + the central air is over 100 amps, is that rule a guidline or a requirement? the owners would much rather save 6 or 700 dollars and just add a sub panel?

mr-jf
this is just a suggestion, what i would do is go ahead and contact the electrician and have him\her calculate the entire house with the new addition included. use nameplate rating on hvac. sometimes it's best to go ahead and do the 200a update in cas of future additions. ken m

I would recommend that the home be upgraded. In my experience owners of 2400 sq ft homes like to keep adding circuits for DIY projects. You're probably already close to the limit on 100A with the sq ft and AC anyway.