Code Change Summary: New code section to address PV Equipment and wiring methods over 1000 Volts DC.

In the 2020 NEC^®, PV system dc circuits were permitted on or in buildings if they were 1000 volts or less per 690.7. In the 2023 NEC^®, changes were made in 690.7 that point the code reader to new requirements in Section 690.31(G) for installations over 1000 volts where PV equipment and wiring methods are permitted to attach to a building under specific conditions.

The opinion expressed in the public input behind the code change was that the 2020 NEC^® language allows PV equipment containing dc circuits rated greater than 1000 volts within mere inches of a building (such as from a nearby ground-mounted array), yet it is not permitted to mount or attach the PV equipment or wiring methods on the building’s exterior wall.

Since the permitted PV equipment and wiring methods would be located outside in open air rather than enclosed by the building, there is less risk than rooftop PV arrays having dc circuits over 1000 volts that penetrate the building envelope.

New Section 690.31(G) permits PV equipment and wiring methods containing PV system dc circuits with a maximum voltage greater than 1000 volts to interface with a building under the following conditions:

(1) Equipment and wiring methods containing PV system dc circuits with a maximum voltage greater than 1000 volts shall not be permitted on or in one- and two-family dwellings.

(2) Equipment and wiring methods containing PV system dc circuits with a maximum voltage greater than 1000 volts shall not be permitted within buildings containing habitable rooms.

(3) Where installed on the exterior of buildings such equipment and wiring methods shall be located less than 10 feet above grade.  Wiring methods containing PV system dc circuits connected to this equipment shall not be permitted to attach to the building greater than 33 feet along the building surface from the equipment.

With certain restrictions, this code change allows inverters and associated dc equipment from a nearby ground-mounted PV array to be mounted on the outside wall of a building other than one- or two- family dwellings.

One of the restrictions in item (3) specifies a maximum height requirement. PV equipment and wiring methods having PV dc circuits exceeding 1000 volts cannot be installed higher than 10 feet above grade when attached to the building. The intent is to prevent the installation of overhead conductors.

Item (3) also provides a maximum length the PV dc wiring and equipment can interface with the building to ensure the PV installation has very limited contact with the building.

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.