PanelPanel LabelDo plug-in subfeed lugs exist that are rated for use with a GE Powermark Plus loadcenter? I have a circa 1980s TM2020R Mod 1 loadcenter that is fully populated with THQP breakers and was planning on adding an adjacent loadcenter for additional space. I was hoping to use THLK2200 subfeed lugs to feed that panel, but documentation states that the THLK2200 can only be used with Powermark Gold loadcenters.

If subfeed lugs are not an option, are the expensive/hard to find TQDL/THQDL breakers my only options for a >125A feeder to a subpanel?


  • Can you post clear photos of the labeling on your panel please? Also, are you planning to stick with GE for the new loadcenter, or...? – ThreePhaseEel May 5 '20 at 22:40
  • I've posted an image of the labeling on the panel door. There is some additional small labeling on the side wall but it is too obscured by wiring to see well, let alone photograph. I was planning on using a GE for the new loadcenter for consistency sake, but am not tied to that. – doctoris May 5 '20 at 23:26
  • Can you get us a clear shot of the loadcenter interior with the deadfront removed for that matter? We need to see which of the main neutral lugs are removed in order to plan this out correctly so we get matched wire lengths on the neutrals. – ThreePhaseEel May 6 '20 at 0:39
  • I've added a picture with the deadfront removed. If it matters, the neutral landing on the leftmost lug is from a SEU cable to a stove outlet that is no longer in use so can probably be removed. I also already have 2 additional 192A7663G13 neutral lugs. – doctoris May 6 '20 at 1:21
  • I take it you were planning on putting the new panel to the left of the existing panel, then, given that the meter's on the right, and there are conduits below? (Above won't do, because you'll hit the 6'7" height limit the NEC sets on breaker handles.) – ThreePhaseEel May 6 '20 at 1:43

Paralleling subfeed lug blocks is an option...

While the THLK2200 indeed is only supported by PowerMark Gold loadcenters, there is nothing that prohibits one from putting subfeed lug blocks (as opposed to actual breakers) in parallel, provided they support attaching large enough wires (1/0 or larger), and the attached wiring obeys the NEC rules for parallel conductors, namely that the wires must all be the same length, use the same kind of wire, and be derated appropriately if they're in the same conduit. This lets us use a pair of THLK2125s to get 200A total out of this panel, despite the lack of a single 200A subfeed lug block that'll do the job.

Furthermore, one can also use subfeed lug blocks to backfeed a panel provided they are held down with the appropriate retainer kits, just as one would do with a backfed main or generator breaker. This allows us to come up with a way to handle the length-matching issue without undue difficulty, given that your panel does not have any global restrictions on stab ampacity given on its label.

Of course, you'll need neutral lugs to match, and for this, we'll use a 286A8894G1 add-on neutral lug kit, mounted to the left-hand inboard neutral lug position at the top (the "tab" there), along with the existing 2/0 lug at the right-hand inboard position. The two subfeed lug blocks, then displace the existing breakers at the top of the existing panel, going across (these breakers will have to move no matter what, since your panel only permits T(H)QDL breakers to be fitted in the top four full-width spaces).

As to the feeder itself...

For the feeder, we can easily get 6 1/0 Al (or even 2/0 Al if you want some extra safety margin in case something comes undone) XHHW-2 wires in a 2" rigid nipple fitted between the two loadcenters, coming out the bottom of one side of the existing panel and going into the bottom of the adjacent side of the new panel. You'll want to order a single length of XHHW-2 Al wire for this and cut and tape it yourself (black, red, white is fine) so that you can ensure that you have equal lengths of wire and that everything is correctly phase taped so you don't accidentally short something out by way of mixing your wires up. The conduit nipple, then, serves as the grounding path between the two enclosures; you'll need to make sure that the locknuts are made up tightly for this, and that any paint on the insides of the boxes around the locknut contact areas is removed.

...and the choice of loadcenter

We already know that we'll need a 200A or 225A NEMA 3R (outdoor/weatherproof), main lug loadcenter for this new panel. The only question left, then, is a matter of spaces, and for that you'll want to go as big as you can get. If you're sticking with GE, this means using a TLM4020RCU or perhaps a TLM4225RCU; however, this limits you to 42 spaces, with no way to migrate breakers from the old loadcenter to the new since neither of those panels can accept half-width (double-stuff, THQP) breakers.

With these panels, you'll want to leave them configured as main lug, but leave the normal main lugs unused. Instead, you'll want to fit another pair of THLK2125s in the topmost set of spaces, going across, held down by a THQLRK4 backfeed retainer kit (one retainer kit holds down both subfeed lug blocks).

The incoming feeder neutrals, then, land on both neutral lugs in the new panel, one per lug, and a TGK42 ground bar will need to be fitted to the new panel as it's a subpanel. You'll also need to be careful when wiring up the new panel to make sure that both wires connected to the A leg in the first panel connect to the A leg in the second panel, and likewise with the B leg, lest you create a 240V short that the main breaker in your existing panel will tell you about with no shortage of urgency when you try to turn the power back on!

If you don't want to go through this hassle, though...

If you find the above process to be too much of a hassle, though, there is a way to get a 200A breaker for your panel, it just takes a bit of cleverness and understanding of corporate parentage. You see, GE has a subsidiary known as Midwest Electric that makes RV pedestals, metering equipment, and such; what's not as commonly known is that this equipment uses GE breakers, despite the fact that they have their own breaker part numbers. So, as far as I can tell, the Midwest CB2200B should be equivalent to a TQDL21200, and somewhat more available as well (KSCdirect has the former for about $300 at the time of this writing).

With this, we can use the same 2" nipple to the new panel, but a somewhat more conventional feeder consisting of two 250kcmil Al hots, run from the lugs on the new feeder breaker to the main lugs on the new panel and a pair of 1/0 or 2/0 Al neutrals, run from the top set of neutral lugs (with a 286A8894G1 fitted to the inner left-hand neutral lug mounting position, again) on the existing panel to the neutral lugs on the new panel. In this case, phase taping isn't critical, but it's still important to make the paralleled neutrals the same length! (Your panel apparently can't accept the larger neutral add-a-lugs for some reason, based on its labeling, and I can't find any instructions that say otherwise.)

  • Thank you for the very thorough and insightful answer. It certainly gives me another option to consider, but I'll have to weigh whether losing 8 spaces between the two panels is worth it. One question though, why is the 192A7663G13 lug not allowed? Is it since it is not listed on the panel labeling? If so, why is the CB2200B permitted (or the THLK2125)? – doctoris May 6 '20 at 13:50
  • @doctoris -- I can't find any installation documentation for the 192A7663G13; you might be able to use it instead of the 286A8894G1 in your panel, but I'd need to see the installation documents to make sure – ThreePhaseEel May 6 '20 at 22:33

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