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Images of the situation: https://i.stack.imgur.com/YdONl.jpg

The previous home owner had this panel installed, or did it himself.

It appears he just connected 4AWG cable to the main lug and fed that into the subpanel.

The subpanel's ground and neutral bars appear to be bonded. 2 4AWG cables come from a single lug on the subpanels neutral bar, and then feed into the main panel, splitting and connected to the two bars in the main panel.

This doesn't seem right to me. I am really curious what other have to say. Maybe it's up to code, but I'd be surprised.

3 Answers 3

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Yes, this is pretty much "amateur hour". The first thing you do when putting panels side-by-side is drill holes in the stud between so you can pass a few conduits between the panels. That makes it easy to relocate circuits, you can just pass the hot and neutral through the pass-thru, and don't need to re-route the Romex cable. The feeder wires need to all be in the same conduit. And this also makes the feeder wires MUUUUCH shorter, which makes them much cheaper and pays for all the conduit bits and then some.

#4 copper is good for 85A.
#4 aluminum is good for 65A.
The feeder needs to be protected by the appropriate sized breaker (rounding up to the next size is allowed, so 70A or 90A breaker). Tapping the utility side of the main was illegal for 2 reasons: that and also the terminals are not certified for 2 wires, especially not 1 copper and 1 aluminum wire. Nothing wrong with aluminum as long as you respect terminal rules. (in the 1970s, they didn't).

You will need to identify either one 240V circuit or two 120V circuits in the main panel, and relocate them to the subpanel via a pass-thru. It looks like any of the circuits on the left side could be re-routed without needing to extend their wires.

Once you have 2 circuits freed, you can install a 70A or 90A breaker in the main panel to feed the sub properly.

Removing the wires from the main breaker will require a "meter pull" because that is service wire that is energized 24x7. I'm guessing the last guy just loosened the lug and slid the wire in there. The meter pull may in turn require a permit from the city.

Note how the drywall is proud of the service panel face, so the panel cover does not screw all the way down. You're accustomed to seeing this with junction boxes but it is not allowed with service panels.

So you have a bit of a task list here.

  • Have meter pan pull, and disconnect illegal subpanel wires from main breaker.
  • Optional: During meter pan pull, reposition main panel so it will be flush or proud of properly installed drywall (this is not).
  • Disconnect and remove subpanel to allow drilling holes through studs for pass-thru's. Preferably 1 large and two 3/4" pass-throughs. The large is for the feeder. Choose places where the knockouts on the two panels line up. Should be doable - they're both GE.
  • Reinstall subpanel and install RMC conduit nipples.
  • Purchase accessory ground bars for subpanel (model numbers listed on label). Move grounds to them. Remove subpanel neutral-ground bond.
  • Replace feeder with a legal 4-wire feeder bringing neutral and ground separately. Choose wire size appropriate to the ampacity you want. #1AL or #3Cu for 100A. #2AL for 90A (significantly cheaper).
  • Re-route hot and neutral of 2 circuits to new panel to breaker of appropriate size.
  • Position feeder breaker so it is opposite SMALL breakers, to avoid overloading bus stabs. (prior nitwit needlessly put 110A on top 2 bus stabs).
  • Install EV charging circuit or better, empty 1" conduit into garage. I know it's needless, but you'll get significantly better offers when you sell the house. Shame not to do it while you're in here.
  • Drywall to suit.
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  • Thanks so much! I appreciate the thorough and detailed response. Have yourself a great weekend!
    – Andrew V.
    Sep 17, 2022 at 0:18
  • Add to the list: Seal knockout opening at bottom left corner of main panel. Verify none of those branch circuits is directly behind the screw holes for the panel cover. Identify all of the white wires attached to the breakers (I count at least 4?). Check for double-tapped neutrals, they look awfully close to each other. If pulling a permit, do NOT drywall. Sep 17, 2022 at 0:47
  • isn't there some sort of exception if the run is less than 10 feet?
    – Jasen
    Sep 17, 2022 at 10:16
  • @Jasen There's no exception allowing wires to be under-breakered or feeders to be unbreakered. Service wires are totally unprotected, so they must take the shortest necessary distance from meter to main breaker, that is probably where the 10' comes from. However the service wire extension to the "sub"panel is not necessary at all. Sep 17, 2022 at 19:54
  • @Harper [240.21(B)(1)]
    – Jasen
    Sep 17, 2022 at 20:49
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Sub panel must have ground and neutral separated.

Sub panel seems to be just 120 volt capable, so no way to get 240 volt circuits. Odd but think it is okay.

Looks like a metal conduit system to the sub panel for ground, but circuits from sub panel look to be a cable system. Your local might not allow this mix.

You do not have a ground bus in the sub panel. Will need to see if you can buy one, and if you can connect ground bus to the conduit path. The sub panel is using the neutral bus for ground back to main panel.

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  • Any idea if NEC allows you to tap into the service lugs to feed a subpanel. It seems very strange to me.
    – Andrew V.
    Sep 16, 2022 at 21:24
  • Don't think so, since no way to cut the power between main and sub besides working with live power. If there was a problem would need to pull the meter or wait for the power company to come by,unless lucky to have a disconnect at the meter.
    – crip659
    Sep 16, 2022 at 21:33
  • That's what I figured, thanks. This is a little out of my comfort zone so I'll give the electrician a call Monday morning. I appreciate your help.
    – Andrew V.
    Sep 16, 2022 at 21:38
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It looks like a failed attempt at a feeder tap.

Assuming those feeder wires are shorter than 10 feet and the supply is capable of no more than 10 times their current limit (so 650A for aluminum ar 950A for copper) then this is basically allowed under 240.21(B)(1)

The problems I see.

The ground to neutral bonding in the main panel should be checked, if this bonding is being done via the subpanel that is not right and and should be corrected first.

Using black for neutral and ground is allowed (in 4 gauge or larger) but they must be marked (white) with paint,tape,or heatshrink at both ends.

Using doubled wires is not allowed one of those neutrals must go

The panel is only wired for 120V this seems strange, but is not illegal.

all those breakers and terminals being used as cable joiners, should be checked to see if that is specifically allowed with that model of breaker or terminal.

the second panel is missing a ground bar.

the second panel might be missing a ground connection (but if the conduit is metal that qualifies)

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