Which NEC section covers underground service conductor sizing and ampacity?

Which NEC section covers underground service conductor sizing and ampacity?

• A. 230.23
• B. 230.31
• C. 310.12
• D. 430.248

Answer: (B)

The key idea is that underground service conductors are sized and their ampacity determined under the NEC provisions for service conductors. This part of the code specifically governs how the conductors that bring power from the utility to the building are sized when they run underground, including how to match conductor size to the calculated load and apply any necessary adjustments or temperature corrections for an underground installation. That focus makes this section the correct reference for underground service conductor sizing and ampacity. The other sections address different topics—general conductor sizing rules for non-service conductors, motor circuits and protections, or other service-related details that don’t specifically cover underground service conductor sizing.

The key idea is that underground service conductors are sized and their ampacity determined under the NEC provisions for service conductors. This part of the code specifically governs how the conductors that bring power from the utility to the building are sized when they run underground, including how to match conductor size to the calculated load and apply any necessary adjustments or temperature corrections for an underground installation. That focus makes this section the correct reference for underground service conductor sizing and ampacity.

The other sections address different topics—general conductor sizing rules for non-service conductors, motor circuits and protections, or other service-related details that don’t specifically cover underground service conductor sizing.