Change Summary

• A new 408.6 was added to Article 408 requiring switchboards, switchgear, and panelboards to have a short-circuit current rating not less than the available fault current. This requirement goes further to require the available fault current and the date the calculation was performed to be field marked on the enclosure at the point of supply (for other than one- and two-family dwelling units).

Expert Analysis

For the 2020 NEC, all switchboards, switchgear, and panelboards (including panelboards at dwelling units) are required to have a short-circuit current rating not less than the available fault current. The enforcement community has a difficult time enforcing proper fault current ratings on such equipment as switchboards, switchgear, and panelboards without the knowledge of the available fault current. The equipment is usually properly marked with the short-circuit current rating by the manufacturer, but there is typically no information on the jobsite as to the available fault current at the equipment.

These new requirements will make it much easier to assure that equipment is being properly protected. The NEC clearly addresses short-circuit current ratings for specialized equipment such as industrial control panels in 409.22, elevators in 620.16 and industrial machinery in 670.5. The Code should also include this requirement for switchboards, switchgear, and panelboards. The marking requirement in 110.24(A)assumes that service equipment should be rated at or above the available fault current, but it is not clearly indicated. This requirement is not on the forefront of most installing electricians and this new rule in 408.6 provides field inspectors with a clearly stated, enforceable requirement.