Introduction - electrical service upgrade with new trenching

I have spent over a year dealing with PG&E in norther California for a service upgrade. I have a very long driveway and the trenching requirements have been very strict. I have now passed all the underground PG&E inspections - let me tell you, those inspectors have been STRICT. The type of sand was a big deal, the type of detectable tape to bury, the horizontal elbows, dealing with an upgrade to the splice box on the street. Now I am almost done repaving the driveway.

Next - Main panel

The problem now is the main panel. I have been in a waiting list since last year. PG&E approved the Siemens panel MC0816B1400SCS that I selected with the help of this web-site. I was recently told by the "guy" that unless I'm willing to put down between 5 to 7k I won't get one. I asked another distributor that only deals with SquareD and they also said 400A panels are minimum 8 to 10 months out, but they have no idea when really. And they also hinted at people "paying more" to get them. Also, I tried to search nationally, I emailed and called distributors across the nation - I found nothing available. The story I was told is that new construction in several places is not electric only (no gas) and the big developers take all the 400A panels bypassing the regular distribution channels. I have no idea if this is what is actually happening, what I know is that I cannot proceed because I need a solution.

Dual panel?

I read so many posts on this website about dual-200A panels. That would serve me well if it fits my application, however I have to go through PG&E first so that they can approve the meter base, and then (I guess) deal with the city for the two 200A panels downstream of the meter.

In practice, if I understand correctly, I will need to buy this new class 320/400A "meter base" (am I using the correct terminology?) that has no breakers but two sets of pass-through lugs. Physically adjacent to this, two "regular" 200A panels that will feed my 4 subpanels. As I will not have branch circuits coming off these panels, I should be able to use physically smaller ones, and get physically large (40 circuit or so) sub-panels - is my understading correct? While this is obviously going to "work" from an electric point of view, it has to pass inspections and has to be practical. Not to mention the 2020 rule of 6 whole discussion, to this day I am still confused by that.

Here is a schematic of what I think it might be: (edit: what I put as "circuits" should probably be "spaces") Proposed schematic

Final question

I have checked on the SquareD website and they do not seem to offer a standalone meter base with a 320A socket. I am definitely open to other manufacturers but can maybe anybody suggest a model number I can use as a reference?

  • that doesn't sound like home improvement question... Jul 27, 2023 at 20:18
  • Can you clarify? This is for residential setting. The numbers are in the linked post diy.stackexchange.com/questions/232892/… In short, main home, detached garage with metalworking workshop, outdoors kitchen, pool area Jul 27, 2023 at 20:21
  • This question might also help. diy.stackexchange.com/questions/242678/…
    – crip659
    Jul 27, 2023 at 20:23
  • Yes @crip659 that is one of the posts I have read. However I wanted to confirm, with the help of the above schematic, if my understanding was correct. Jul 27, 2023 at 20:24
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    @aaaaasaysreinstateMonica -- class 320 service is very common for large all-electric homes, even though it's not strictly necessary Jul 28, 2023 at 3:08

1 Answer 1


How 400A was historically done

Traditionally, 400A service involves a simple 400A meter pan with customer-side terminals that take two wires each, up to 300 kcmil typically. (note the meter pan is not UL-Listed for paralleling, and as such, the only legal use of it is what I'm about to say.)

From these terminals, two runs of 250 kcmil were made to each of two 200A main panels. This was, y'know, back in the day when you could have no outside disconnect at all, firemen just pulled the meter (dangerous). So these main panels were typically indoors.

Now, in some California cities, outside disconnects were required. In that case, they would just put the two panels outdoors next to each other and "call it a day".

Or, for a more deluxe install, they might get two standalone 200A breakers and stick them right next to the meter pan, and those were the mandatory outside disconnects, and then main feeders would go indoors to the regular panels located "wherever". And the 200A outside disconnects could certainly have 4-8 auxiliary breaker spaces for feeding subpanels etc, i.e. the classic "no-meter" 200A ranch panel.

The old Rule of Six

A "main breaker" was allowed to actually be up to six breakers. So a house might have a 12-space panel outside with a 30A breaker feeding dryer, 30A feeding water heater, 50A feeding range, 40A feeding A/C and 60A feeding a subpanel with all the other circuits. These all were the "main breaker". They even made panels with an internal subpanel so it could all be in one enclosure, but that's been banned for awhile.

The NEC 2020 world, and 230.71.

NEC 2020 requires an exterior disconnect. That's nothing new; some cities have required that for ages and I've already covered how to deal with that. That would be easy. (and might well be easy still).

The new wrinkle is NEC 230.71. It is saying up to six main breakers are allowed, but must be separated, via one of several methods listed in 230.71(B):

  • (1) A separate disconnect each in its own enclosure
  • (2) Separate service panels, each with a main breaker
  • (3)(4) Two or more disconnects may be in a single enclosure, only if there are internal dividers or compartments separating each disconnect.

So the most expedient way to comply with this (and also the outdoor disconnect requirement) is to have two outside disconnects (which could be 200A ranch panels without meter pan) fed straight off the meter, and those are outside.

NEC was only adopted by a large number of states in the last year. Anytime that happens, supply can lag code changes. So in light of the shortages, I would probably use a simple meter pan and separate 200A standalone main breakers (with or without 4-8 auxiliary breaker spaces e.g. a meterless 200A ranch panel).

PG&E's right to tell you which equipment to use pretty much ends at the meter, unless grid-tied solar is involved. So PG&E should not be holding you up over what is physically outside the meter pan. The ruling factor here (the person to please) will be your AHJ - permit issuing authority.

  • Hello thanks for the exhaustive answer. PG&E however wants to know what I put the meter into, and I would like to have them approve it before I buy. I really like the idea of the "simple meter pan". Is it not what I put in my drawing above? Where is my mistake (if any) in that drawing? Thanks! Jul 28, 2023 at 7:03
  • Square D, Eaton, I cannot find a 400A or 320 class meter pan. Siemens makes it really difficult to navigate their "industry mall". While searching, I have found an interesting product they say it's been designed specifically for NEC 2020 230.71 compliance: s3.amazonaws.com/dcc-data-extract/new-delta/asset/Compas/daily/… (I know this is not just a simple meter pan, I just found it while searching) It seems however nobody really has these product numbers. Jul 28, 2023 at 7:22
  • Note: I need a ringed, "manual bypass", 320A meter socket product as instructed by the utility. Jul 28, 2023 at 7:24
  • @Alessio Yes, your drawing seemed correct to me. Your problem is the Internet. Take this life lesson - The good stuff is not on the Internet. You need to put shoes on for this :) You should be able to walk into any electrical supply and have a conversation about service equipment. Their entire service area is PG&E territory, so they know what PG&E wants. Also talk to your AHJ - however NEVER ask a general electrical question you could as easily ask us, because they will cut you off if you do. Jul 28, 2023 at 18:47
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    Of course, none of what I discussed here has been at a home improvement store. It's places on the industrial part of town that cater exclusively to electricians, have a bench where you ask for things and they get them from the back OR (in my case) they involved a salesperson that sat with me to try to find something adequate Jul 29, 2023 at 4:09

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