Contractor is installing circuits in a 2in EMT conduit. For derating per 310.15 number of conductors at 40% = # 8 size of circuit conductors. The engineered drawings directed the EC to install 5, # 12 grounds for these circuits as the EGC. The drawings also directed them to install 5, #12 isolated EGC for these circuits. I believe that the EGC should be a # 8 to comply with 250.122 B. Does the code state a size required for the Isolated EGC or should it be sized the same as the EGC.