Diving a bit deeper. How popular are the plug-on neutral load centers?
I think at this point arc-fault CBs are required for new construction in all states?

Asking because I don’t know…

Was the problem with Challenger breakers or the Challenger panel?

Seems like if you had a Challenger breaker box and you put in Eaton Breakers (as appears to have been done), you should be fine. Eaton breakers are fine.

Home depot will have the breaker you need for this project. I had to do something similar in my office trailer Reno back in May and it was an older panel that took Eaton breakers… maybe Challenger, can’t recall.

I like Square D products but they are getting increasingly difficult to find. Only a few places carry them and they must be bought at industrial / electrical supply places. Cutler-Hammer is also good (Mfg by the same company), Siemens would be my other choice after them.

My HD has "only" 378 results when searching for Square D:

http://forums.pelicanparts.com/uploa...1691762245.jpg

My bad. I was originally talking about connecting to one of my subpanels which is a newish Challenger. The Challenger panel seems to be working okay at this point and I've installed Eaton breakers without an issue I know of.
Then I switched gears asking about replacing my other subpanel which is maybe 70+ years old and is outside. It was the original main panel but is now a subpanel.

That's why all my questions re. Homeline vs QO and arc-fault/etc. I'm trying to get grip on the specs. of a new subpanel to replace my 70+ year old panel.

A minor update on this.
I've identified two panels, for the exterior Square D QO load center 125amp plug-on-neutral exterior NEMA3R and the same panel for the interior but the interior version.
These panels can use PoN breakers and regular non PoN breakers as long as they are QO.
Looks like the most of the duel function breakers are designed for double taping.
Interior Panel = QO124L125PG
Exterior Panel = QO124L125PGRB