Strange panel configuration

Just the normal overhead feed to POCO meter.

I would referred this to a license electrician for evaluation and wiring jacket needs to be trim back also, And make sure all panels are bonded and grounded.

Already done! There were numerous other issues with the panels. Strangely enough the branch wiring, what was tested and what was visible in the attics, was all good.

The way the panels in the OP are configured is very atypical. I’ve never seen anyone attempt to do it like that in many thousands of panels I have inspected. Large homes will commonly have multiple panels installed as service equipment to provide more than 200A service capacity. You will almost always see a gutter installed between the meter and the service equipment containing the splices for the SECs and the conductors coming off the meter will be sized for the aggregate load.

The conductors need to be properly sized. That is a key deficiency with the installation shown in the original post.

What is depicted in the original post is an aberration. I would report it as improper. Don’t try to rationalize what was done there. When configuring distribution/ sub-panels, they will draw their current from the upstream service equipment and whatever is in between and the overall current is limited by that service equipment. If a house has a demand of more than 200A, it’s common to accomplish that by installing multiple pieces of service equipment (e.g., 2x200A) to meet the calculated demand as you see in the image that I posted.

There can be up to 6 service disconnects meaning that you could have had 6 panels with 200 amp mains in each of those panels serving as the service disconnects.

The service entrance conductors (SEC’s) in this case (the conductors coming from the meter) need to be sized according to the calculated load of all of the panels. If the calculated were 200 amps you could technically have 200 amp SEC’s feeding all 3 of the panels. You would not need to add up all of the sizes of the service disconnects (3*200 amps) and size the SEC’s for 600 amps. I know it sounds crazy but that is what the NEC allows.

As an FYI, there is no requirement to trim back the cable sheathing.

Mike, I don’t believe there is a rule regarding length of sheathing into the panel board and I think the minimum is 1/4" into the panel board.

There is no maximum or minimum length for that matter when entering a panel (technically a cabinet by NEC definition). The 2017 added a 1/4" requirement for NM cable entering metal boxes but that did not exist prior to the 2017 NEC.

Thanks for the technical definition…cabinet. :thinking:

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I just wanted to note that there is a distinction between a metal box and a panel enclosure which is a really a cabinet. :smiley:

Yes, I really appreciate it, Robert. :smile:

That’s exactly what I was doing. I tend to over think the electrical aspect of the inspection. There’s so much to know and it’s the most hazardous for home owners.

I guess they’re the masters of what needs to be done.

Thanks a lot guys! Cleared some stuff up for me!

Hi Robert, I get that the panels (enclosures) are in parallel, and would need a total system load calculation for whether the existing SEC is sized correctly.
You mention the paralleled twisted bare conductors are a violation (neutrals). Would every panel be independently grounded? Or can that be done in parallel as well (assuming large enough conductors for the load)?

Since each panel is a service each one would have it’s own main bonding jumper (MBJ) which connects the neutral to the enclosure and equipment grounding bus. That connection is what provides the “grounding”. It’s a direct connection of the equipment grounding conductors to the neutral that provided a low impedance path for the fault current back to the utility transformer. There would not be an equipment grounding conductor (EGC) run with the service entrance conductors only a neutral.

There may also be a grounding electrode conductor (GEC) run to each panel as well or the GEC may terminate somewhere else upstream such as at the meter. You might also find a GEC run to a water pipe electrode with taps to each panel. There are several different code compliant ways to run the GEC.

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Thanks for your reply and further info Robert. EE low voltage terminology doesn’t always match electrical ‘speak’.

I will have to further investigate: “equipment grounding conductor (EGC) run with the service entrance conductors only a neutral.”

Yes that should read “no” equipment grounding conductor…

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