Breakers are feed with aluminum wiring. The markings on the breaker say, CLT? Are these rated for aluminum?

CTL is a model or style, UL Listing Code and so on. If the breaker is rated for AL wiring it will say things like

AL/CU, AL, AL9CU and so on…I dont believe CTL means anything in regards to the acceptance of AL wiring.

U.L. Listed suitable for use as service equipment, complies fully with NEC and UL requirements for Class CTL

From UL- CTL Circuit Breaker — has physical size, configuration or other means which, in conjunction with the physical means provided in a Class CTL assembly, is designed to prevent the installation of more circuit breaker poles than the number for which the assembly is designed and rated.

“CTL means “Circuit Total Limiting”. “Circuit Total Limiting” (CTL) was introduced when the words “A lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed, rated, and approved” was added to Section 384-15 in the 1965 NEC”.

Circuit Breakers: CTL Assemblies Mike Holt

Belleville Home Inspector

The breakers had no other markings?

Then assume CU only and 60 Degree Ampacity ratings.

CU only means copper connections correct? Did an inspection that had aluminum wiring with these types of breakers.

CU means “copper,” yes. AL means “aluminum.” Some will be marked CU/AL - copper or aluminum.

I have never seen a termination that was not marked for cu or al or both. The markings are probably on the side or near the termination, where they can’t be seen without removing the breaker. I seriously doubt there are residential breakers out there not rated for both.

Brian I a not sure but in an older breaker that has no markings at all on it ( yes, there are some out there ) might not have a temp rating, Conductor type or even an AIC rating…so we ( in the teaching world ) assume 60 Degree, CU and 5,000 AIC when it is not showing anything.