This column completes last month’s discussion on the history of working space requirements in the National Electrical Code (NEC) . Now, it is time to look to the more recent past and even into the future.
Section 110.16 is back in use; this time to require arc flash warning labels on switchboards, panelboards and motor control centers to protect electrical workers. This warning label would serve as a reminder for qualified and unqualified workers about the hazards of arc flash. The labels are not required in dwellings but are required elsewhere. More detailed requirements for marking emerged in NFPA 70E along with new and improved work practices.
Section 110.26(A)(1) was restructured, including changing exceptions into positive text to make the text easier to read.
Section 110.26(C) was revised to better provide requirements for working space egress. It now requires at least one entrance of sufficient area to provide access to working space about electrical equipment. A new 110.26(B)(2) was added to provide requirements for working space around large equipment. Large equipment was equipment rated 1,200 amperes (A) or more and over 6 feet wide. The new requirement called for two entrances, one at either end of the equipment. It also specified the minimum dimensions of the entrance. The door was required to be equipped with panic hardware and to open in the direction of egress, because the most important function of the “entrance” is as an exit to leave the space containing electrical equipment. However, if the workspace was doubled and there was a clear, unobstructed path to the exit, a single exit was permitted. These exit requirements are in place to allow a worker to escape an arc flash incident. Often, I hear comments that you can’t run fast enough to escape an arc flash. This is very true, but the quicker you are able to get away from an equipment burn-down, the less serious your injuries may be. Panic hardware is required to facilitate a quicker exit than possible with twist-type handles.
Some foreign systems would be permitted in the area above the dedicated space if leak protection apparatus was provided. Since the dedicated space extends 6 feet above the equipment, a suspended ceiling would be considered a foreign system, so an exception was added to permit suspended ceilings with removable panels within the 6-foot zone.
The requirement for a second exit where the space contains large equipment was reconsidered in this cycle. It was decided that the mitigating factor was the equipment’s ampere rating, rather than its physical width, so the requirement was changed to apply to equipment rated 1,200A or more, regardless of the width.
The panel decided to return to the 6-foot-width dimension for large equipment in 110.26(C)(2). It was decided that the lack of a physical dimension could require a second entrance for fairly small equipment, just because it was rated 1,200A or more. The requirements were also revised to clarify that doors must open in the direction of egress; in other words, the door should open in the direction of exit from the area containing the equipment.
Not all electrical equipment is in a dedicated electrical equipment room. Some is in open areas. With the existing wording, the exit requirements would apply, regardless of how far away the exit door is. Eventually, you would come to an exit from an indoor space containing equipment. Some questioned how far away from the equipment the exit requirements would apply if the equipment was in an open area. The requirement was clarified to indicate that it applies to doors providing egress less than 25 feet from the nearest edge of the working space. Doors beyond that would not be governed by the requirement because the worker would be far enough away from the equipment.
Service disconnecting means and overcurrent protective devices are required to be readily accessible. However, locking of electrical equipment rooms and enclosures is an important way to prevent injuries. The Code was changed to indicate that locked rooms and enclosures were still considered accessible to authorized personnel.
This cycle revisited the intrusion of meters into the workspace. A new exception makes it clear that other electrical equipment that is associated with the electrical installation is permitted to extend no more than 6 inches beyond the footprint of other electrical equipment that is above or below it. This includes meter sockets. However, the meter itself is not subject to the 6-inch limitation. It can extend further into this work space. Often, the meter is not installed when the inspection takes place.
Illumination requirements around switchboards and panelboards were also revised to prohibit the required lighting for the working space from being controlled by automatic means only. Occupancy sensors would not be prohibited, as long as there is a manual means of keeping the area illuminated. The intent is to prevent loss of illumination during maintenance work, which could endanger workers.
In this cycle, the panel decided it needed to revisit the requirements for personnel doors to improve workers’ ability to escape in the event of an arc flash incident. Now, the panic hardware for doors within 25 feet of the nearest workspace edge is required to be listed panic hardware. Listed hardware can be expected to be more reliable because it is subjected to extensive laboratory testing to ensure it will function as intended after a number of cycles of operation. The requirement’s threshold for the listed panic hardware on doors was lowered from areas containing equipment rated at least 1,200A to at least 800A. It is important to note the requirement for a second exit is still triggered by equipment that is at least 6 feet wide and at least 1,200A.
Also new for the 2014 Code was the clarification that equipment space and working space requirements also apply to outdoor installations. There is often a desire to cluster all of the outdoor equipment together to consolidate all infrastructure equipment in one location, neglecting the future maintenance needs.
The large equipment requirement where a second exit is needed is proposed to be modified so that it would now also apply to service equipment with multiple disconnecting means, where the combined rating is 1,200A or more.
Working space for duct heaters began to present challenges in the 2014 NEC . It was recognized that this equipment was often located in limited work spaces above the ceiling where all of the working space that would be required in 110.26 is not likely to be available, nor would it be practical. Section 424.66 required duct heaters to be installed in a way that permitted access to the heater. A task group was formed to develop requirement for space for duct heater access. The result was 424.66(A) and (B).
The biggest change for the 2017 Code was to again consolidate all of the workspace into 110.26. This change brought the new language from 424.66 into a new Section 110.26(A)(4), “Limited Access,” and it was broadened so that it no longer applied only to duct heaters. It could also apply to some crawl space installations.
The next edition of the NEC is scheduled for publication in September 2019, so the work is underway. It is too early to say how it will turn out. So far, it looks like there will be a revisions to the informational note to 110.26(A) that points to NFPA 70E for information on establishing an electrically safe work condition. In addition, the large equipment requirement where a second exit is needed is proposed to be modified so that it would now also apply to service equipment with multiple disconnecting means, where the combined rating is 1,200A or more.
Requirements are also proposed to be added to 110.26(C)(2) to prevent open equipment doors from impeding the entry to or egress from the working space of large equipment. This would minimize the chance of entrapment between open equipment doors and an obstruction such as a wall facing the equipment. For this cycle, it is proposed to modify 110.26(D) to prohibit automatic means of controlling illumination in electrical equipment working space using means such as motion sensors or timers.
The evolution of the space requirements is a tribute to the responsiveness of the NEC and its committee members. Field experience with requirements indicates which requirements work and which ones don’t. It also provides the opportunity to address new challenges that installers face in dealing with limited available space. Space is always going to be limited in indoor and outdoor installations. We will continue to need to be prepared to respond to new field problems and new types of equipment so that we are facilitating the safe and sound growth of the electrical industry.