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I currently have 100A service and I want to upgrade to 200A. At the same time, most of the wiring in my house is old and I don't trust it. Finally, the current main panel is in a bad place in the basement, which I eventually want to finish.

Jurisdiction is Dayton OH. Please let me know if I'm missing anything, have anything wrong, or if you have general pointers for me to watch out for.

General plan is to build an entirely new electrical system in place, have it rough-in inspected, finish up as much as possible - then, in one day, have the "final inspection" performed, power shutoff, new service connected, meter swap, and power reestablished. Then I can gradually rip the old system out. Specific details below:

Right now, I have just a meter on the outside and the main panel inside. Leaving those in place, I plan on adding a meter/main to the outside of my house, relatively close to where the meter is currently (a dozen feet over or so, closer to where I want the panel on the interior). Per my understanding, this should satisfy the 2023 NEC (not sure if it was introduced earlier, and I know that OH isn't on that yet - just future-proofing) requirement to have an external/outdoor disconnect/shutoff.

I'll plan on running 4/0-4/0-4/0 AL SER from the service connection point (on my roof) to the meter/main on the side of the house - one conductor for each phase, plus a conductor for neutral. I'm unsure if I need a conduit for this cable, or what kind of routing requirements it has as far as avoiding windows/etc., and would appreciate a code reference here. (My understanding is that I connect to the meter/main, and let the utility company wire the other end to the service connection point with the power shut off). This meter/main will also be the location of the bonding neutral and ground.

From the meter/main, I'll use a subpanel lug or 200A breaker to connect a 4/0-4/0-4/0-2/0 AL SER cable from the meter/main to the subpanel, mounted in the basement. This cable passes through the external wall, but not underground - I want to keep it as short and straight-shot as possible, ideally only 5-6 ft. The subpanel, which is kinda acting as my main panel (since I don't want to hook most things THROUGH my external wall to the meter/main) has a 200A main breaker that I'd like to keep/use since this will be my primary control point for anything electrical in my house; I'd rather avoid going outside and flipping breakers if I need to do stuff. Per my understanding, I'd only need a breaker on one end - hence the lug kit in the meter/main - but it may be that a 200A breaker is just easier there.

This subpanel will not have ground bonding, since that's supposed to be done in the main panel only. The meter/main will also have a surge protector installed in 2 of the slots; I think this means I don't need a surge protector on the subpanel?

From the subpanel, I'll be running all of my house circuits on various AFCI and/or GFCI breakers where appropriate; once it's inside I'm more confident with what needs to be done.

Is anything obviously wrong with this plan, or do you have recommendations/tips?

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  • Is the cable you're planning to use for the service entrance SER or SEU? I ask because SER generally isn't available in the construction (3x 4/0 without ground) you're looking for for that Commented Nov 25, 2023 at 23:54
  • @ThreePhaseEel Probably SEU, though if I can only get my hands on the 4/0-4/0-4/0-2/0 SER then I might just leave that last conductor unused if that's kosher (I'm not sure).
    – user112697
    Commented Nov 26, 2023 at 0:04
  • So are you moving the main, or converting it to a sub? I lost the thread on that at some point in here.
    – KMJ
    Commented Nov 26, 2023 at 7:26
  • The current internal main panel will be disconnected and eliminated by the end of it all. Internally I’m adding a new main. @KMJ
    – user112697
    Commented Nov 26, 2023 at 15:30

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It looks solid. The only thing I would suggest is a generator interlock in the new panel. Then you do one of two things. Either (with AHJ permission) use the generator interlock breaker temporarily to feed this panel as a subpanel from the original panel prior to Cutover Day, or simply run it out to an appropriately located inlet and feed the inlet from a jumper cord off the old panel.

Then you can energize those circuits early for testing, and Cutover Day really just is throwing two breakers.

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