At work (industrial setting)we have devoloped temporary 480 VAC splitter boxes that are constructed to allow a 60 amp circuit to be split into 2 - 30 amp circuits. Each output circuit is fused for 30 amps. Unfortunately, it has been a pratice to use these on a 30 amp circuit and rely on the 30 amp circuit breaker for protection. I have always been taught that this is wrong. My managment is willing to change this if I can prove it is againt NEC codes, but I do not know where this is covered. Can you tell me where this information is located so I can determine if this pratice needs to be changed? Thank You