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Oregon (NEC 2023)

The power meter from the utility is mounted on an exterior garage wall. Right next to the meter box, but on the interior side, is a breaker box with a single 200A breaker. That breaker then feeds a typical 200A load center on the opposite interior garage wall, which itself has a main breaker. The load center has neutral and ground bonded.

I have no idea why there is that first interior breaker, but it did make me think: is that downstream load center then technically considered a subpanel? And thus, would it need to have neutral and ground separated?

In the upstream interior breaker box, there is no bonding between the neutral and ground (which is just a grounding rod in that box). I don't even see a way you'd bond them because they aren't close together like in a typical load center, which usually has a piece of metal and fastener spots specifically designed for bonding.

Update: I just thought of a possible explanation: the load center is newer than the interior breaker box I believe. Possibly the old load center was where the interior breaker box is now, and the interior breaker box is serving as a big "splice" to extend the service wires from the meter and ground rods to the new load center, which is just across the garage. Either way, I still don't know if this theory would change anything about the load center technically being a subpanel under the NEC 2023.

Update 2: Here is a photo of the interior breaker box. Upon closer inspection, I now see there are some small lugs next to the neutral lugs that could be used to bond the ground wire. But for whatever reason, someone installed the small grounding bar and has the ground wire from the load center and grounding rods connected there.

Interior breaker box

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    How is the 200A disconnect labeled? This seems not quite right, in any case, though...
    – ThreePhaseEel
    Commented Apr 13 at 3:01
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    How many wires run between the 200A disconnect and the load center? Are there separate neutral and ground wires between the boxes?
    – A. I. Breveleri
    Commented Apr 13 at 3:49
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    Is the exterior box serving as an emergency disconnect?
    – whatsisname
    Commented Apr 13 at 18:03
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    Can you post photos of the inside of the disconnect box?
    – ThreePhaseEel
    Commented Apr 13 at 19:38
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    @tau is there a label on the inside of the disconnect box's door, or somewhere on one of the sidewalls for that matter?
    – ThreePhaseEel
    Commented Apr 14 at 18:55

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I'm not sure why you're on NEC 2023 when the installation looks a lot older than 2023. Your installation must comply with the NEC version in force on the day the building permit is pulled.

I have no idea why there is that first interior breaker

I'm puzzled by that too. Certainly under NEC 2020 and many much older city regulations, such a disconnect must exist and be on the outside of the building, so firemen aren't getting blinded by arc flash from pulling meters under load.

But there it is.

but it did make me think: is that downstream load center then technically considered a subpanel? And thus, would it need to have neutral and ground separated?

Not necessarily. You have to see NEC 230.85, which specifically allows disconnects to exist prior to the "main breaker" -- provided only certain loads are tapped off that pre-main-breaker disconnect. Generator interlock, surge suppressor, solar, that kind of thing, and those are specified in 230.82. Note the marking requirements in 230.85.

I mean, I'm assuming an installation under NEC 2023 rules. Since your NEC edition may predate NEC 1999 even, 3-wire feeders were legal then, and that's that.

What if I was forced into NEC 2023 rules? Well, that can happen if you replace the interior panel (the one with all the breakers). That triggers a requirement to bring your NEC 230.85 outside disconnect into full NEC 2023 compliance.

And while you would need an outdoor rated panel (you can't just flip this one, it lacks a NEMA 3R rating)... your outdoor panel could have several breaker spaces for things allowed under NEC 230.82.

I would avoid an all-in-one (meter+main+breakers) because one very fun thing you could put in that outside panel is a home battery system like a PowerWall (or the equivalent that uses your EV's battery for most of the energy storage). However that type of system requires a typically automatic isolation switch (disconnect + auxiliary contact to indicate it is disconnect) that sits between the meter and the solar and battery system breakers. With all-in-ones, that's impossible. (Why not use a meter collar? Because the utility can veto meter collars, and probably will.)

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  • i only mentioned nec 2023 to give some reference to what is currently being used in my area, but all of this work was probably a few years old according to the owner. although the load center is a square d homeline with PON, so the load center cant be very old. there is no permit sticker on the load center though... so it sounds like youre saying that having this interior main breaker was okay in nec 1999, and so if this setup was done then, the load center would not need to separate ground and neutral?
    – tau
    Commented Apr 15 at 17:04
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    @tau yes, looks fine for pre-NEC 2020. Under NEC 2020 the labeling in 230.85 would be required, and the disconnect would need to be facing outside and in an outdoor rated box.
    – Harper - Reinstate Monica
    Commented Apr 17 at 22:46

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