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I was planning to use one of the two free knockouts in my meter-panel for a 1.5" conduit containing conductors for a new sub panel.

Opened the main to find both of them blocked by a wireway. Assume this was for a ground level service entry, but mine is overhead.

I cannot find any info from Eaton. The panel is an Eaton mbx2040b200bts.

Is there any chance of a listed method for using the knockouts in the bottom left corner?

I'll be relocating a few of the circuits from this panel to the sub, so the mess in this picture will get a bit cleaner.

The other option is moving the leftmost 1.5" conduit to the new sub. It feeds another sub panel on the opposite side of the house. New sub is 125 amp, candidate for moving to it is 100, and currently experiences no more than 40 amps of load, but that may grow in the future.

Eaton diagram of panelenter image description here

enter image description here

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  • Carefully investigate if the wireway is removable. If it is, contact the manufacturer to see if you can get a mod kit for the panel.
    – K H
    Apr 19, 2021 at 10:34
  • Why is there a short jumper from the top right breaker (part of a duplex) to the neutral/ground bar? Or is that just a weird optical illusion of two wires perfectly overlapping based on the angle of the photo?
    – FreeMan
    Apr 20, 2021 at 12:30
  • Oh wow, that would be crazy. Luckily it's an optical illusion.
    – Evan
    Apr 20, 2021 at 21:34

2 Answers 2

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Check your feeder size

That feeder coming off those 100A breakers needs to be either #3 copper or #1 aluminum. If it is #2Al / #4Cu, then you must downgrade the 100A breakers to 90A. Those are the rules, I don't write them. If you were misinformed that #2/4 is good for 100A, that happens a lot because people love to misinterpret 310.15(B)(7), or blindly "take on faith" answers from others who did so.

If conduit fill allows, lean toward aluminum wire. It's always worked fine on large feeders like this.

Accommodating that extra conduit

No need to crack the wireway issue. We can do this another way: install a splice box within 2' of the panel, and fit maximum conduit size between splice box and panel.

Pick either the feeder/conduit on the left, or the feeder/conduit on the right.

Pull out the existing feeder Note the concentric knockout that it comes in, is not at its maximum available size. Break off the concentrics so it is at its maximum size (2-1/2"??).

Install a new large metal junction box below the service panel. The top hole gets a hole in the top the same size as the knockout you just opened up. The bottom gets a hole fit for attaching the existing conduit (1-1/4"?)

Install an EMT or Rigid metal conduit nipple that is less than 24" long between the service panel and this new box.

The existing conduit will be in the way of the new box. Cut the existing conduit out of the way, and apply fittings so it now enters the new box.

See what we did there? You now have a 2-1/2" (?) pipe from the service panel to new box, and a 1-1/4" (?) pipe going wherever that conduit currently goes.

Now, pull the wires back into it. We're back to status quo ante.

Now, bring your NEW conduit into the side of the new box. Pass its wires through the box and up to the service panel through that nice fat conduit. Voilà!

If other conduits are in the way, like that 1/2" conduit, bring them into the new splice box also. More's the merrier!

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  • Thank you, that is a great work around.
    – Evan
    Apr 20, 2021 at 19:07
  • Will double check wire next time I open up the panel. Pretty sure those are #3, but will downgrade if not.
    – Evan
    Apr 20, 2021 at 19:08
  • Confirmed those are #3. Appreciate your eye for safety.
    – Evan
    Apr 20, 2021 at 19:20
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I remove those if I don’t use them then the KO’s on the side are useable. Looking at the bottom and side nothing is in there. If the opening to the meter base is open I will use a pice of sheet metal to cover the hole. Most are rectangular but if round buy a hole cover that size and seal it nothing fancy needed there.

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  • That standoff on the left side of the wireway is where the current cover mounts. Seems like a big modification to somehow refit that to work. Am I just relying on an inspector not caring that I've made unlisted modifications, or is the mounting system here a non starter for this answer?
    – Evan
    Apr 20, 2021 at 0:31
  • The standoff is a bit far down from the hole you need to block, so you'll probably find it's unrelated to mounting a new cover where you need to. The primary challenge would appear to be safely removing the channel. Usually panels with features like this are made to be versatile in removal of the feature though, so I would carefully examine it to figure out how to remove the channel. Once the channel is removed, the opening between the service side and panel side must be closed. As an electrician I would make sensible mods and point it out to an inspector to have an exception written.
    – K H
    Apr 20, 2021 at 2:24
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    As a homeowner, you might want to contact the inspection office ahead of time and simply ask them what kind of modification will be acceptable, as exceptions for homeowner work can be harder to obtain. Thats why I recommend contacting the manufacturer to see if they have a kit for it, which would just consist of a rated plate to cover the hole when the channel is removed.
    – K H
    Apr 20, 2021 at 2:26
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    The current cover can probably be modified into a suitable plate once removed as you know for certain it's rated for the necessary separation. You don't want pointies sticking into either section of the panel, so you would typically use machine screws, nuts and washers or tapped holes rather than self tapping screws or similar.
    – K H
    Apr 20, 2021 at 2:43
  • I make modifications (punching holes into) every box I install and yes I have removed sections of unused underground feed gutters. In some cases I just removed the angled section maybe a inch or more up from the wide part leaving only the face. I make sure the corner of the dead face mates I can’t remember if it is cut out (I leave the front in place and cut out the unneeded separation). It would be different if the feed was coming up from underground but it is not. I would be more concerned with the inspector pointing out improper bend in the EMT 2 bends the pipe is slightly damaged. K H+
    – Ed Beal
    Apr 20, 2021 at 4:21

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