Do I use the Siemens Type Q Breaker in ITE Blueline Loadcenter panel?
You are looking for a Siemens BL2 (not to be confused with a Siemens BL)
ITE Blue Line loadcenters appear to use a special style of &quot;thin&quot; breaker instead of the more &quot;typical&quot; QP (EQ-P) breaker.  Unfortunately, the ITE Blue Line (not to be confused with the other type BL breaker, which is the bolt-down version of the QP and thus no use to you), only is available in 1 pole up to 50A and 2 pole up to 40A, as per the current Siemens Canada catalog.  So, you'll either need to run a smaller feeder to your subpanel, or have your main panel replaced outright.