I would like to update my main electrical panel from 12/24 space-circuits to 30+

I currently have an EATON BR 125-amp with 4-jaw ring meter socket (MBE1224B125BTS) which is inside the attached garage of my single-family home. I would like to replace it with a 200-amp panel to get a bigger panel without doing a subpanel(s). I would get a 125amp main breaker for the new panel. I'm considering this Square D QO model (QC3040M200S), 200-amp 30-space/40-circuit ringless 5-jaw meter socket.

For the meter socket, what is the difference between ring/ringless and 4-jaw/5-jaw? Can I keep the current PG&E meter I have or would that need to be replaced for this particular panel?

  • Are you dead-set on QO specifically, or SquareD in general, for this new meter main? Commented Dec 5, 2018 at 3:06
  • Not at all. Internet has me leaning towards copper bus which favors QO, CH, PL. My first thought was to have a main panel separate from the meter but I don't really have the space for that with restrictions to placement near gas meter (both mounted inside attached garage) From what I've learned today it seems ring/ringless choice doesn't matter at all, and I'd likely need 4-jaw not 5 which leaves me with BR and Homeline options at home Depot.
    – dabi
    Commented Dec 5, 2018 at 8:09
  • "at Home Depot" -- there's your problem! You should definitely be getting cozy with your local electrical supply house at this point -- they'll have a far better selection in the product lines they carry than the scattershot-at-best nature of what a big-box carries. Commented Dec 5, 2018 at 12:41
  • ok thanks, will do. but to my question - do I need to specifically look for panels with a 4-jaw/ring socket, or does the 4/5 jaw - ring/ringless choice not matter?
    – dabi
    Commented Dec 5, 2018 at 17:19
  • Is flipping the electric meter so it is on the outside of the house an option? Commented Dec 6, 2018 at 0:56

1 Answer 1


General case: your utility sets the requirements for this

Since the meter socket is part of the interface between you and your electric utility, most electric utilities publish a document that specifies what sort of meter socket they want, among the other various requirements and conditions they place on consumers of electric services. For the case of PG&E, this document is called the Greenbook.

In your specific situation...

PG&E is a member of what's called EUSERC -- this is a coalition of utilities that set and use a common standard for metering equipment. In particular, you will need a ring type meter main that conforms to the EUSERC specifications (EUSERC drawing 301, 301A, or 302, to be precise, but if the manufacturer's catalog says that it complies with EUSERC, that's good enough). As a result, the QC3040M200S is not usable for you; in fact, none of the Class 200 (150/200/225A) all-in-one CSEDs in the QO line meet EUSERC requirements, so they're a non-starter for you.

Furthermore, PG&E will not accept a setup with the meter for a single-family residence inside a garage -- this is prohibited by the Greenbook, section 5.3.2, point F. So, you'll have to put the meter-main and any loadcenters on the outside of the garage instead if possible (as you can't put the subpanel by the gas meter either, NEC 110.26A would likely prohibit it even if the Greenbook didn't). Thankfully, this gets them out of the way of the gas meter set, so you now have the flexibility to use a separate meter-main and loadcenter, as described below.

If this doesn't work, then you'll have to find a new home inside for the setup, or hope that PG&E and your electrical inspector will grandfather the noncompliant location.

Avoiding repeating this pickle down the road

One of the problems with "all-in-one" service entrance devices, as you are finding out the hard way, is that they tend to be short on breaker spaces and are hard to expand or replace. As a result, if a meter-main is required, the use of a single-disconnect meter-main or a meter-loadcenter with feed-through lugs in conjunction with a separate 200A panel is a far better choice than a single 200A meter-loadcenter combination from an expansion and flexibility perspective.

Given the lack of options in the QO lineup for this, I would go with a Siemens MC0816B1200E(FN/FT/SN) for the meter main. It is listed as EUSERC approved in the Siemens catalog, has 8 full size spaces for outdoor branch circuits or the like as well as an available secondary main disconnect of up to 50A (useful for an outbuilding), and has a set of feed-through lugs at the bottom of the busbars that can be used to provide the full 200A capacity of the main breaker to a subpanel without taking up any spaces. With this, you can use a 200A panel of your choosing -- I would use something with a minimum of 42 spaces, but would not turn down a 54 or 60 space unit if one was available. Plug-on Neutral is a nice-to-have (albeit not necessary), and since the meter-main provides the main disconnect, you can use a main lug panel for the subpanel.

Sidebar: 4-jaw vs 5-jaw

Self-contained electric meters and meter bases/sockets are not all alike -- they come in various current ratings (or Classes), as well as in various jaw configurations to accommodate different supply systems. The 120/240V split-phase system used for most houses and light commercial buildings uses a 4-jaw meter and socket, as it only needs to be involved with the two hot lines (hot 1 in, hot 1 out, hot 2 in, hot 2 out).

A 5-jaw meter socket and matching meter are used when the service is a "2 out of 3" service, where instead of providing 2 legs 180deg apart from the opposite ends of the supply transformer, you get 2 legs and a neutral 120 degrees (and 208VAC) apart, as they came from picking 2 legs out of the 3 phases provided by a 120/208Y connected three phase supply. Many 4-jaw sockets can be converted to a 5-jaw configuration in the field using a fifth jaw kit, as all this fifth jaw does is supply a neutral connection to the meter so it can correctly measure power in this asymmetric configuration. However, unless you are in NYC (and you aren't), you will only see a 120/208 3-wire service or feed in a high-rise building fed by three-phase electricity.

So, while a 5-jaw socket can be used in a 4-jaw application (with the neutral jaw sitting unused), 4-jaw sockets are more widely available, so that's what I have specified here.

  • Incredible answer, thanks for sharing your expertise. Filling some gaps specific to my situation: Water, gas, and electric all enter the garage in the same front corner (inside), next to the vehicle garage door. No option which meets clearance requirements on outside of home without major construction. Greenbook also prefers gas meter to be outside. All meters are where they were when I arrived, so I'm working with what I've got. My first preference was to separate meter from panel, but again clearance requirements make it tough. Will revisit, maybe can push panel deeper into the garage.
    – dabi
    Commented Dec 6, 2018 at 4:56

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