"Here's the "code book" for HUD." LOL. Although labeled differently, I see we posted the identical link. I, too, live in an area (rural Maine) that effectively requires no permit and no inspection for electrical work. When I asked my local "Code Inspection Officer" (a gravel and concrete guy), he said, "Oh, I verify set-backs and once or twice I've failed buildings for using 16' 2 x 4 rafters, but I don't do electrical." So I pushed him a bit and he agreed to inspect my new garage/workshop building. He had no clue what to look for so I even walked him around, pointing out the various things an inspector might look for (passing each one, naturally) and got him to sign off. That way, I can honestly tell my insurance company that the electrical work was inspected. We both thought the exercise was pretty funny. Anyway, back on topic. Perhaps I shouldn't doubt you, but are you sure you need a service upgrade? A 100-amp service is typically plenty for a mobile home unless there is a lot of electrical heat (e.g., baseboard heaters or heat pump). Have you done a load demand calculation that includes the proposed wall oven? The reason I ask is that I think if you can forego a service upgrade (to 200A?) and replace the panel with physical dimensions not too much larger than the original, you'd be in a pretty good position to argue that, although you've replaced a part (the panel) and added a circuit or two, you haven't voided the "HUD sticker." I think that position is much less defensible if you've upgraded the entire service. But do I know this for certainty? Nope, sure don't.

The CEB panel is now owned by Eaton (Canada) and known as the type PRL1 panel and it takes type QBH breakers. I believe with that panel you buy an isolated ground assembly and move the neutrals (both the incoming feed and all the branch circuit neutrals) to that. You leave the grounds on the existing bar. These things do NOT have the greatest reputation. You might give serious consideration to replacing it with something more modern while you're mucking around with it.

The POCO has its own rules since distribution wiring is not covered by the NEC. The exact point that POCO distribution wiring ends and the NEC comes into play is subject to local laws. Just as an example, in Virginia the POCO is responsible to the input side of the meter pan, but may supply the pan since they have a preferred model.

Wayne, Thanks for replying. 1) I was adding another circuit to the main panel later in the day of my original posting, so I checked the heater circuit. It was 5kW, not the 3kW I originally posted, but it's in addition to the heating element installed as part of the HVAC (probably wasn't clear in my original post)... the cost was $100 if I had the extra circuit installed by the time they put in the main HVAC unit, so I said "why not". This is the circuit I think I can now do away with as it's not needed with the new pellet stove keeping us warm. The "standard" heating element in the HVAC is now the "emergency" element, if you will. 2) So you're suggesting bringing a short main panel circuit outside to the transfer switch, thereby allowing for a single long run from the switch to the subpanel. Hmmm, that idea has a lot of merit. I would definitely want to go with an ATS, then, so I don't have to walk outside to swap things out (and shoveling snow to get to that side of the house... like the 4' we had in 3 days last year :( ). 3) I'll read it after posting this... 4) I was thinking of a Kohler or a Cummins-Onan, though I hear Kohler is often more expensive in the long run because they do their best to force you into using their own guys for general service. In that case, Cummins-Onan has a serious edge.