Background: I have a decent skill set; I've worked in commercial HVAC and facilities maintenance for over 20 years. I'm considered "electrically qualified" at my work and I have a state ticket as an apprentice electrician. I have found a master (with a licensed & bonded company) and a journeyman who are willing to pull permits and work with me, allowing me to do as much of the work myself as possible.
My home is not overly large, about 1200 sq ft with a 720 sq ft attached garage with a 2nd floor guest quarters above it. It was built in 1930 and moved to its present location in the mid-60s, after which the garage and apartment were built as an addition. The main service entrance (200A) is located at the L where the garage joins the home; the drop runs alongside the garage on 2 poles I am responsible to maintain and then turns 90 degrees to enter the main panel. The wiring runs so close to the house that it is impossible to clean or maintain gutters or paint fascia without touching the 240V lines.
The main panel is a modern GE board and most of the wiring was redone by the previous homeowner; he did the work himself but it looks as if he did it right. On the other hand, the garage and apartment are fed by two sub-panels which look as if they were installed by Dr. Frankenstein...there's not even a way to shut power off to them; they're wired direct to the main lugs of the service entrance.
I'm planning to develop a home-based internet business which will entail a server rack and 3000 VA (30 amp) UPS. Also, thinking ahead, there are other potential high-demand items that I may want to install, such as a swimming pool, woodworking shop, and (if she ever moves in with me) my mother's glass fusing kiln (which draws 46 amps at 240V). I could also use that last outlet for a welder or possibly for charging an electric car. I will also want, eventually, to install a whole-house generator to back up the online business.
Bottom line is: I want to upgrade the main service entrance to 400 amps and relocate it to the back corner of the garage where it can be fed from a direct drop from the utility pole. I want to put a new main panel in the garage which will service the circuits there and have a 200A feeder to the existing main panel. I want to make provisions for sub-panels for laundry equipment, the woodworking equipment and kiln, and the possible swimming pool which, along with the water heater and the A/C units for the home and apartment, could be managed by load control relays so that I can keep the size of the generator to 20KW/200A or so.
To place the new main panel in the most convenient location for future expansion I will need to bore through a number of 2x8 joists. That limits me to 2" conduit. After doing a "dream sheet" load analysis, I come up with a need for 400kcmil feeders, a #1 neutral, and a #3 ground. If I use IMC conduit and THHN wire it looks like that fill will be workable...just barely.
Anyhow, I will be discussing all this with my electricians, of course. But I want to have my ducks lined up before I shoot. Can anyone make any suggestions of things which should be considered now, before I start into this? As I said, I've worked in commercial facilities for quite some time but this is the first time I have addressed a project of this scope as a homeowner. Thanks for any help.
EDIT TO UPDATE: Been a long time since I've looked back in here; time to revisit with some updates. I still want to upgrade the service entrance but I'm not in a hurry. I have (with the help of an electrician) rerouted the feed to the two Frankenstein subpanels so that they come off an actual breaker at the service entrance; they're no longer tied direct to the main feed. These panels have the neutrals and grounds commingled which is, I've found, a no-no (although ca. 1965 maybe nobody cared), so they're not long for this world. I'm planning to replace both of them with new 125A GE panels (TLM1212CCUGK).
The plan now is that when I do upgrade the service, I'll get a 320 amp distribution panel and install it at the back of the garage. Preferably with underground conduit going back to the power pole like the neighbor behind me has instead of a "drop". I'll run conduits from the distribution panel to the existing main panel and the two subpanels I'm replacing, and simply install 125 amp breakers to feed each panel. When/if I ever get around to adding a swimming pool I'll put in a fourth branch panel for the pool & spa equipment, fed the same way.
The subpanels I'm replacing will be "convertible main breaker". I'm going to leave the designated main breaker slots unused; if at any time in the future I want to meter the house, apartment, and common areas (laundry, garage, etc) separately all I will need to do is put in the requisite meter cans at the new service entrance, install the main breaker conversion kits, and tie the feed wires in accordingly.
I know I'm moving slowly, but I've had a stretch of unemployment and my current job has been hit hard by the virus panic. Thanks to all of those who gave me ideas and good information.