Code Change Summary: Additional ampacity values for 16 AWG copper and 14 AWG copper-clad aluminum conductors were added to Table 310.16 in the 2026 NEC^®.

SME commentary: The 2026 NEC^® introduces an important expansion of Table 310.16 by including ampacity values in all three columns for 16 AWG copper conductors and 14 AWG copper-clad aluminum (CCA) conductors. This change complements revisions to Section 310.5(A), which reduced the minimum allowable conductor size for copper conductors from 14 AWG to 16 AWG, and for copper-clad aluminum conductors from 12 AWG to 14 AWG. With these reductions, it became necessary to incorporate corresponding ampacity values into Table 310.16 so that users of the Code can apply adjustment and correction factors properly when designing and installing circuits.

The addition of these values is significant because Table 310.16 is the cornerstone reference for conductor ampacity. Without the newly added ampacity values, electricians and engineers would be unable to derate these conductors when subject to conditions such as higher ambient temperatures or installations with more than three current-carrying conductors. For example, the use of the 90°C column with specific conductor insulation types for adjustment and correction calculations is a permitted practice recognized in Section 310.15(A). Before the 2026 edition, without the values shown in all columns of Table 310.16, this flexibility was not available for 14 AWG CCA, limiting its usability in many practical applications.

The acceptance of 14 AWG CCA as a branch-circuit conductor represents the culmination of nearly a decade of testing, evaluation, and debate. Code Panel 6 was presented with test studies evaluating CCA’s performance across a wide spectrum of conditions, including heat rise under normal and overcurrent conditions, long-term thermal stability, and compatibility with commonly used devices and connectors. The test data consistently demonstrated that 14 AWG CCA operated within safe temperature limits when loaded at its proposed 10-ampere rating, even under demanding conditions such as being embedded in wall or attic insulation. Comparative testing further showed that 14 AWG CCA performed at least as well as, and in some cases better than 14 AWG copper when subjected to similar loads and installation environments.

An important detail in Table 310.16 is the introduction of footnote 3, shown under the table at the very bottom as a superscript next to certain ampacity values. This footnote specifies that the value applies only to copper-clad aluminum conductors and not to regular aluminum conductors. This provides clear guidance for installers and inspectors, ensuring that the unique treatment of 14 AWG CCA is correctly applied during design and inspection.

The newly published ampacity values in Table 310.16 also ensure that 14 AWG CCA can be treated consistently with other conductors when applying correction and adjustment factors in both the 75°C and 90°C columns. This alignment mirrors how 12 AWG CCA has long been treated in Table 310.16, with ampacity values in the 90°C column as well as the 75°C and 60°C columns. Providing similar treatment for 14 AWG CCA allows installers and inspectors to apply the NEC^® rules uniformly and confidently.

These updates to Table 310.16 allow designers, electricians, and inspectors to work with complete information when addressing conductor sizing. They remove ambiguity, ensure consistency across conductor types, and recognize both historical performance data for 16 AWG copper and the extensive technical validation of 14 AWG CCA. By making these changes, the 2026 NEC^® delivers greater clarity and flexibility while maintaining its primary mission of electrical safety.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2026 NEC^® edition of NFPA 70.

2023 Code Language:

310.3(A) Minimum Size of Conductors. The minimum size of conductors for voltage ratings up to and including 2000 volts shall be 14 AWG copper or 12 AWG aluminum or copper-clad aluminum, except as permitted elsewhere in this Code.

2026 Code Language:

310.5(A) Minimum Size of Conductors. The minimum size of conductors for voltage ratings up to and including 2000 volts shall be 16 AWG copper, 14 AWG copper-clad aluminum, or 12 AWG aluminum, except as permitted elsewhere in this code.