bigbluewirenut,
In my past life I worked as a Square D Field Engineer for 11 years. You need to talk to your SQD residential expert.
The use of non-Class CTL breakers in non-Class CTL panels is a violation of the UL listing. Is it done often? You betcha, but it still ain't legit.
To my knowledge there are no non-residential panelboards that are Class CTL. In fact the Square D Digest says these "cheater" breakers are for use in single-phase QO loadcenters and not in NQOD commercial/industrial panelboards, quote "Replacement Tandem Breakers for Use In Old Style Non-Class CTL QO Load Centers".
