Time to ask a question.
Is this an engineering excersize, or is this something that will be fabricated and inspected?
You have 3.6KW of heat trace in each circuit. (120 volt, 30 amp) Or, are you protecting the circuit at 30 amp, and the actual load is less?
Further, have you planned for ....."427.22 Ground-Fault Protection of Equipment. Groundfault protection of equipment shall be provided for electric heat tracing and heating panels.
This requirement shall not apply in industrial establishments where there is alarm indication
of ground faults and the following conditions apply:
(1) Conditions of maintenance and supervision ensure that
only qualified persons service the installed systems.
(2) Continued circuit operation is necessary for safe operation of equipment or processes.
Does the install qualify as an industrial establishment?
How do you propose to provide the OCP you mention?
I see a 100 amp secondary main OCP (breaker) minimum #3 THHN Cu, and branch cbs as required. The 4 amp PLC protected by a 15 amp cb, or in-line, or fuse block if you so choose.
