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I have two 200 Amp Challenger Main panels in my garage. I am running 255ft of AL wire (4/0 4/0 4/0 2/0) through an underground conduit to a new 200 Amp Square D Homeline subpanel in an outbuilding.

The Challenger panel is outdated and the Main Lug kit that the label (see Photo) says to use (MLK2200C) is completely absent from the internet. I don't know what may have replaced it, but my best guess is that it's the Eaton BRPSF225 or BRS225? However, those are a pretty pricey item to buy just to connect some cables (in my opinion).

So, I was looking at the panel and am wondering if some decent lugs (like the Southwire LUG250K-6AD) could possibly be used to connect the conductor cables at the location I circled in red in my photo? The big issue I have been having is the 4/0 cable, and finding connectors big enough to handle 4/0. Some have said I don't need it, but I would rather future-proof than have undersized cable down the road.

Main Panel Label

Main Panel possible lug connection location

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  1. No, you may not freelance feed-through lugs. You must use parts specifically listed or classified for your panel.

  2. 4/0 aluminum wire isn't rated for 200A at 75˚C terminations (the max terminal rating you'll see for residential equipment), so you couldn't even feed it from proper feed-through lugs given the 200A main breaker. (See a wire ampacity chart)

  3. If you haven't actually bought 4/0 wire yet, consider if 2/0 aluminum on a 125A breaker would be sufficient. 2/0 will fit directly onto the lugs of an Eaton BR2125/C2125 breaker that'll fit your panel. Coincidentally(?) you already have one installed but unused. When you do a proper Load Calculation you may find you can't even spare 125A, depending on what else you currently feed from this panel.

  4. FYI every Challenger "Type C" breaker in the pictured panel is defective and needs to be replaced with something legitimate. They don't actually trip when they should which can lead to bus damage, fires, etc. See Challenger Bus panel

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    Added Load Calc reference, hopefully that's OK. Because I really don't want to write a separate answer when yours covers the big issues (Challenger problems, wire size, subfeed breaker). Nov 5, 2023 at 22:40
  • 2/0 copper on the 125A breaker. That will let you go as much as 175A in the future. There's your expansion headroom. Or just run nice fat conduit, throw whatever in there today and upgrade anything later. Nov 6, 2023 at 23:36

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