Thank you for the replies. Ibpod -- Yes, you are correct about splitting the property and potential problems with the current setup. However in this case it does not matter, as per the city the lot is too small to split. So I'm not worried about that in this case. Bus_driver -- There are two separate meters. The power runs from the pole, to the mast at the front house, and then down through two separate meters. From there it branches directly to a) the 100A panel for the front house, and b) the 100A main disconnect for the back house. This main disconnect then runs the 150 feet underground (#2/0 copper) to the 100A panel on the back house. I hope this helps answer questions, Please let me know if there is anything else. In your estimation, if I were to upgrade to 200A, would I need to upsize the #2/0 copper wire feeding the back house? 150' of #3/0 is EXPENSIVE these days.

Inspections are as individual as the persons who do them. I have encountered within one inspection department interpretations of the code that differ 180 degrees. In one such large department, one inspector refused to recognize Article 110.26(A) (Exception No.1) while another inspector agrees that it means just what it says. Your best bet is to just have your electrician apply for a "service change" -- nothing more. The outcome is uncertain.

Thank you ronnatalie. I will do that. I've wanted a geo thermal system for over 25 years. Yes, its expensive upfront - I hesitated long over that, but thanks to the new Federal Tax Credit of 30% which is making it possible for me (Thank you Pres. Obama), plus a thousand back from my local utility company, its ROI through fuel savings looks to be about seven years. If I replaced my conventional system with another one and added a/c, which I do not have now, it would cost me a bundle too - I got estimates on several before making my decision. But, and this is the important factor - I would never get my money back because I would keep paying for oil or gas to run it even if I bought the most efficient system available. Nothing is as efficient as geothermal. It does run on electricity, but it doesn't take much to keep it humming. Yes, the solar voltaic panels are also expensive, and I thought long and hard about them too, but between NY state giving a tax credit, the federal government giving one and my local utility offering a generous rebate, I can just swing it, though it's going to be tight. The pay back on it will be about six years. After that, the majority of my annual power use will be covered by what is generated. I know others who are putting it in too, for the same reasons. The lady who cuts my hair and her husband put one in several years ago and love theirs. They have only four years to go before their power is free. Meanwhile, they love the days their meter runs backwards. I can say with confidence that the tax credits are putting a lot of people to work in the geo and solar fields. Installers from both are doing good business around here and are actively hiring, which is nice to see. As this is our forever home, I decided it's time to make it more up to date and functional. We've been making do with one bathroom for four people, a 6' x 9' kitchen and no closets as antique homes never had bathrooms or closets. The addition will allow me to put in two bathrooms and a downstairs bedroom for us as we age - and closets, finally. What I'm doing is not extravagant. No home theaters, no big garage, no pool. I will be putting in a foundation, shelling it in, then finishing it as we can. I spent today insulating part of what will be our new kitchen one day. I'm itching from fiberglass bits. You can bet that when the addition is uo and ready to be insulated - by me - I will be using ... denim. It's treated with boric acid so that it's fire resistant, bugs won't live in it and mice won't either. Which is a lot more than I can say for the dirty old fiberglass and rock wool insulation I have been pulling out. Yuck.

Thanks for the response. Comments: - I'll check the big box store on the QO ground-bar kit. I had forgotten the panel doesn't include one. - Since the distance between the two is only about 15 feet, but very bendy, the cable's likely the easier way to go for a pseudo-temp install. What trade names would Cu 2-2-(2/4)-6 feeder cable go by? That's what I'm thinking would be proper gauge to eliminate the chance of balking. - The old panel location will likely have to become a junction box, as you note, but that room (laundry) has a (currently violating code) counter and cabinet right in front of the panel...so it's fine for junction box; not so much for a breaker panel. I'm ripping the room down to the studs to remodel as a gift to the better half, so the fewer "old-work" wires that are in place when I do demo/plumbing/framing, the better. - That should have been "stub-out" and yes, I just want to make sure an inspector isn't going to fail me if I have a bunch of wire-nut terminated coils hanging next to the panel... Thanks. Dan