Code Change Summary: Section 310.10(D) was revised to clarify that insulated conductors permitted to be bare do not need to have a sunlight-resistant rating.

SME commentary: In the 2026 NEC^®, Section 310.10(D) has been revised to address confusion surrounding insulated conductors exposed to direct sunlight. The prior code language required insulated conductors or cables exposed to the rays of the sun to either be listed as sunlight resistant or covered with a material that was listed for sunlight resistance. This raised questions when applied to conductors that are permitted by the NEC^® to be bare, such as equipment grounding conductors (EGCs), grounding electrode conductors (GECs), and bonding conductors. If the Code allows these conductors to be installed without insulation at all, then there is no technical basis for requiring sunlight resistant insulation.

The revised 2026 NEC^® language in 310.10(D) now provides three clear compliance paths:

• First, conductors may be insulated and listed as being sunlight resistant.
• Second, they may be covered with an insulating material, such as tape or sleeving, that is listed as sunlight resistant.
• Third, for insulated conductors permitted by the NEC^® to be bare, such as an EGC, they may be bare, or if insulated they would not be required to have sunlight-resistant insulation.

The third allowance is new and resolves the issue that previously led some inspectors to require installers to strip insulation off of GECs or other grounding and bonding conductors installed where exposed to the sun because the insulation was not sunlight resistant. Such practices were unnecessary since Article 250 permits these conductors to be insulated or bare.

The change is consistent with how grounding and bonding conductors function. The purpose of an EGC is to provide a low-impedance path for fault current or to bond non–current-carrying conductive parts, not to carry continuous load current. Sunlight degrading insulation on such a conductor does not affect its ability to perform its function. By removing the implied requirement that these conductors have sunlight-resistant insulation, the NEC^® eliminates a source of confusion and prevents inspectors from enforcing an unlisted standard that does not exist.

The committee statement accompanying this change emphasizes that the revision is intended to clarify, not to relax, safety requirements. Conductors or cables that are required by the NEC^® to be insulated must still comply with the sunlight resistance provisions if installed in locations exposed to direct rays of the sun. However, if the NEC^® permits the conductor to be bare, then any insulation or covering that may be applied does not need to be rated for direct sunlight exposure.

For contractors and inspectors, this revision simplifies installation practices and aligns enforceable requirements with the NEC’s overall structure. Installers will no longer be asked to strip exposed equipment grounding conductors or grounding electrode conductors unnecessarily, and inspectors will have clear guidance that a sunlight resistance rating is not needed when the Code already permits the conductor to be bare. This results in consistent application, reduced labor costs, and elimination of a practice that had no impact on 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:

310.10(D) Locations Exposed to Direct Sunlight. Insulated conductors or cables used where exposed to direct rays of the sun shall comply with one of the following:

(1) Conductors and cables shall be listed as being sunlight resistant.

(2) Conductors and cables shall be covered with insulating material, such as tape or sleeving, that is listed as being sunlight resistant.

2026 Code Language:

310.10(D) Conductors Exposed to Direct Sunlight. Conductors exposed to the rays of the sun shall comply with one of the following:

(1) Be insulated and listed as being sunlight resistant

(2) Be covered with insulating material, such as tape or sleeving, that is listed as being sunlight resistant

(3) Be bare or have insulation or covering that is not required to be sunlight resistant where bare conductors are permitted elsewhere in this code