Recently, a question was raised about where the means of egress from a working space started and stopped based on changes that occurred in 110.26(C)(3) for 600-volt (V) or less installations and in 110.33(A)(3) for more than 600V installations in the 2008 National Electrical Code (NEC). To fully understand the effect of these changes, a careful study of the text in the 2005 NEC-—as well as how the relocation and text change in the 2008 NEC for the requirements for personnel doors affects how we deal with entrance to and egress from electrical equipment areas—is necessary.
In the 2005 NEC, entrance into a working space is covered in 110.26(C)(2) for large equipment rated at 1,200 amps (A) or greater and 600V or less but only where the equipment contained overcurrent devices, switching devices or control devices. This large equipment required at least one entrance at each end of the working space with the entrance to be at least 24 inches wide and 6 feet, 6 inches high. The entrances did not require doors, just entrance areas to provide a means to access the equipment and then to safely exit to an area away from the equipment. If personnel doors were provided as part of the entrance to the area, however, 110.26(C)(2) required these personnel doors to open in the direction of egress. In other words, the doors must open out of the equipment space. Any door that opened from the equipment room into another area must be equipped with panic bars, pressure plates or some other device that would latch the door closed but would open under simple pressure. This simple pressure device would permit an injured worker to open the door with any part of his or her body since the hands might have been burned in an electrical explosion. Doors opening into a corridor were an issue because these doors could impede corridor egress and be a building code violation. So either the doors would be required to be recessed into the corridor, or the door must fully open to extend not more than 7 inches away from the corridor wall. Remember, these spaces did not require a door, but if one was installed, the door was required to comply with the previously mentioned requirements. For the 2005 NEC, the panic door applications only applied to large electrical equipment of 1,200A or more. These same requirements applied for an entrance at least 24 inches wide and 6 feet, 6 inches high for access to electrical equipment rated over 600V; however, unlike the 600V installations, there wasn’t a requirement for the amperage to be a minimum of 1,200V.
For the 2008 NEC, the word “egress” was added so that the requirement for entrance into and egress out of the working space is now clearly covered in 110.26(C). The requirement for personnel doors with panic hardware was also removed from 110.26(C)(2) covering large equipment rated at 1,200A or more with equipment rated at 600V or less and where the equipment is more than 6 feet wide, so the requirement for panic hardware on an entrance and egress door is now in 110.26(C)(3). Where equipment is rated at 1,200A or more and contains overcurrent devices, switching devices or control devices, a personnel door providing entrance into and egress from the working space must have panic hardware; also the door must open in the direction of egress. In addition, any personnel door or doors within 25 feet of the nearest edge of the working space must have panic hardware. For example, a door that provides entrance into and egress from electrical equipment rated at 1,200A could open into a small room with a janitor’s floor sink with an additional door leading into the hallway. If both doors are within 25 feet of the outside edge of the required working space based on 110.26(C)(1), both doors must open out and be equipped with panic bars, pressure plates or other devices. Similar to the new 2008 NEC requirements for under 600V installations, the same changes were made in 110.33 with a new 110.33(A)(3) that applies specifically to personnel doors providing access and egress from high-voltage equipment.
Since these requirements are specifically covered in the National Electrical Code and not in the building code, electrical contractors, designers, and electrical engineers should provide detailed information to architects and owners of the buildings on the personnel door requirements in the NEC to ensure this very important requirement is provided. Providing panic hardware on the doors and ensuring that the doors open out of the working space where 1,200 ampere or greater electrical equipment is located is a very important safety consideration for any electrical personnel working on this equipment.
ODE is a staff engineering associate at Underwriters Laboratories Inc., in Research Triangle Park, N.C. He can be reached at 919.549.1726 and firstname.lastname@example.org.