A 480Y/277 Volt, 3000A service is fed from an outdoor, 2500 kVA transformer with an impedance of 1.5%. The service entrance conductors consist of 8 parallel sets of 500 kcmil, XHHW-2 conductors installed in 3.5” rigid metal conduit. The service raceways are required to bonded to the grounded service conductor per 250.80. However, since the grounded service conductor is also a 500 kcmil, XHHW-2 conductor, it has been decided to use bonding bushings and a supply-side bonding jumper instead of the grounded conductor itself. What is the minimum size copper, supply-side bonding jumper required by the NEC to bond these raceways to the grounded service conductor?
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