Code Change Summary: Cable Type TC-ER can now be used as underground service conductors.

Section 230.30 is in Part III of Article 230 which applies to underground service conductors. These are the conductors between the service point and the first point of connection to the service-entrance conductors in a terminal box, meter, or other enclosure, inside or outside the building wall.

Section 230.43 is in Part IV of Article 230 and applies to service entrance conductors. These are the conductors between the terminals of the service equipment and the service drop, overhead service conductors, service lateral, or underground service conductors.

During the 2020 NEC^® development process, item 20 was added to Section 230.43 permitting the use of TC-ER cable (Tray Cable suitable for Exposed Run between a cable tray and the utilization equipment) to be used for service entrance conductors.

This may have been a slight mistake. In hindsight, regular TC-ER cable has not been evaluated for service entrance applications.

Cable Types SE and MC are also permitted to be used as service entrance conductors. During the listing (certification) process, these cable types are subjected to an overload test, joist pull test, and a sunlight resistance test. Regular TC-ER cable is not subjected to these tests during the certification process.

In the 2023 NEC^®, Section 230.43 was changed. Line item 20 still permits TC-ER cable to be used as service entrance conductors, but only if the cable is identified for use as service entrance conductors. Requiring the cable to be identified for service entrance use means that the cable will be subjected to the same tests as other approved service entrance cable types.

TC-ER cables complying with the additional tests will be identifiable to show that they are suitable for use for service entrance applications and to differentiate them from regular TC-ER cable which has not been evaluated for service entrance applications.

In the 2023 NEC^®, item 11 was added in Section 230.30(B) to allow TC-ER cable to be used as underground service conductors but only if the cable is identified for service entrance use and direct burial applications.

Additionally, 2023 NEC^® Section 336.10 (which covers uses permitted for TC cable) added new item 12 to permit TC-ER to be used for service-entrance conductors “where identified for such use and marked Type TC-ER”.

Finally, new item 21 was added to Section 230.43 in the 2023 NEC^® which permits flexible bus systems to be used as a wiring method for service entrance conductors. This aligns with new Article 371 covering Flexible Bus Systems.

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 2023 NEC^® edition of NFPA 70.