Which of the following conductors are permitted by the NEC® to be installed in the same raceway with the service entrance conductors?

• A. supply side bonding jumpers
• B. sub-panel feeders
• C. branch circuit conductors
• D. none of these

Answer: (A)

The key idea is how the service entrance raceway is used for grounding and bonding versus carrying branch currents. The service entrance raceway is where the service conductors come in and where the bonding and grounding arrangements for the building are established on the supply side of the service disconnect. The NEC allows the only other conductor in that same raceway to be the supply side bonding jumper, because this jumper is part of the equipment-grounding/bonding system and does not carry normal load currents that would need separate overcurrent protection or create interference with the service conductors’ protections. It’s a bonding connection needed to tie the grounding electrode system to the service equipment.

Sub-panel feeders and branch-circuit conductors, on the other hand, are normal current-carrying conductors that originate downstream of the service disconnect. Keeping them out of the service raceway helps prevent unwanted heat, electrical noise, and coordination issues with overcurrent protection. They require separate raceways or proper segregation unless specifically permitted by other parts of the code.

So, the only conductors permitted in the same raceway with service entrance conductors are the supply side bonding jumpers.