When installing main circuits to swimming pool equipment I usually use a ground that is one gauge smaller than the two hots and neutral. Example: 30 amp circuit 3 #10 wires and 1 #12 ground with a distance of 100' to 150'. The equipment consists of 2 1.5 horsepower pumps and another 1400 watts of misc load. An inspector said I must use a # 10 ground. Is he right? Which part of the code pertains to this issue? thanks