While attending a National Electrical Code meeting in Albuquerque, N.M., I raised a question about a requirement inserted into 110.26(C)(2) in the 2020 NEC, revised in the 2023 NEC and revised again in the 2026 NEC. The question was thoroughly discussed, resulting in a comment by the group that a public input would be a good idea for the 2029 edition. 

No one really disagreed with a possible change to the section in question after I explained the original concept that caused it to be inserted into the 1978 NEC. The text in question involves providing one entrance to and egress from the required working space of not less than 24 inches wide and 6½ feet high at each end of the working space for large equipment with a combined rating of 1,200A or more and combined width over 6 feet.

A reason to change

The original reason for the text was an event that occurred about four or five years prior. Three employees of a communication company were pulling a large cable (using a metal fish tape) into a downtown high-rise building in Phoenix. There was only one means of entry or egress from the electrical equipment room, which also contained a 4,000A, 277/480V service entrance section mounted on a maintenance pad and adjacent to the area where the work was done. 

Inadvertently, one of the communications employees kicked the loose fish tape away from where they were working. The metal fish tape went under the large switchboard and into the enclosed busbar, resulting in a huge arc flash. The three employees could not leave that area safely. Two of them died from the burns they received. 

The original Proposal No. 100 advocating for this text change was to require two means of entry or egress in equipment rooms for equipment that was over 6 feet wide and 800A or more. The change that occurred in the comment stage stated that, “For switchboards and control panels rated 1,200A or more and over 6 feet wide, there shall be one entrance not less than 24-inches wide at each end where reasonably practicable.” 

New text changes

Until the 2020 NEC, this text remained relatively unchanged, but this edition added text to read as follows: “For large equipment that contains overcurrent devices, switching devices, or control devices, there shall be one entrance to and egress from the required working space not less than 610 mm (24 in.) wide and 2.0 m (6½ ft.) high at each end of the working space. This requirement shall apply to either of the following conditions: (1) For equipment rated 1,200 amperes or more and over 1.8 m (6 ft.) wide; (2) For service disconnecting means installed in accordance with 230.71 where the combined ampere rating is 1,200 amperes or more and over 1.8 m (6 ft.) wide. Open equipment doors shall not impede the entry to or egress from the working space.”

This change to reference compliance with 230.71(B) and the combined ampere rating of 1,200A or more and more than 6 feet wide could and does apply to service disconnecting means of six 200A panelboards or more, each within individual enclosures or three 400A panelboards, or a 400A panelboard with an 800A panelboard, or any similar combination. I don’t believe it was intended for this section to cover large equipment of a combined 1,200A or more and a width of more than 6 feet, but that is exactly what we now have or similar wording in the 2020, 2023 and 2026 editions. 

Asking the important questions

Would there be a real hazard of exiting an area for a service with six disconnects where a single 200A panelboard enclosure is involved in an arc event, since the other five immediately adjacent to that one are in separate enclosures and unlikely to also be involved in the arc event? I certainly agree with the 1,200A or more and more than 6 feet in width, since that clearly is a safety issue, but I do not agree that the other combinations mentioned previously are a safety issue. I also wonder how many electrical inspectors and electrical plan reviewers are requiring two means of entrance and egress from these areas with combined service equipment rated at 1,200A when installed, as mentioned previously, in separate enclosures. 

I could even have 12 100A service panelboards in proximity of each other where each of the six disconnects are supplied by separate services based on 230.2 in the 2020 and 2023 editions. I believe a tentative interim amendment is warranted.

marK c. ode