I recently purchased a house that I am fixing up for resale. I upgraded the service to 200amps and installed new main distribution panel. Approx 70% of the house has been rewired and is being fed by the new panel. Six existing 20 amp circuits are being fed by a federal pacific sub-panel.

For obvious reasons I want to replace the FPE Panel. I want to run these six circuits back to my new main panel rather than replacing the sub-panel. The new panel located 20’ away on the exterior of the house.

I would delete the sub-panel, splice the conductors and run them to the new panel in 1’ EMT

Here are the questions:

Can I just run # 12 THHN for each of these circuits or do I need to derate?

Are there any other pitfalls to this plan??