Having adequate working space around electrical equipment is essential. Article 110 in the National Electrical Code (NEC) contains requirements for this access. Part II in Article 110 pertains to systems rated 1,000 volts (V), nominal, or less. Section 110.26 contains almost two pages of provisions covering spaces about electrical equipment. As stated in 110.26, access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of the equipment.
Most of this section’s subheadings are divided into additional subheadings. For example, the subheading “Working Space” in 110.26(A) contains five subheadings: “Depth of Working Space,” “Width of Working Space,” “Height of Working Space,” “Limited Access” and “Separation from High-Voltage Equipment.” Most of these topics focus on the worker by ensuring there is enough working space in front of and around the electrical equipment once it is installed. The requirements pertaining to entrance to and egress from the working space ensure the electrical equipment is readily accessible. These requirements also ensure there is a clear escape route if an electrical incident occurs while a worker is near energized equipment.
Requirements in 110.26(E) pertain to dedicated equipment space. Dedicated equipment space is required for all switchboards, switchgear, panelboards and motor control centers. It is essential to be able to add or remove raceways and cables to these types of electrical equipment sometime after the original installation. Requirements in this section are in place to ensure there will be enough room above and below these specific types of electrical equipment. Other types of electrical equipment are not included in the list requiring dedicated equipment space because access to other types of equipment after the initial installation is usually not needed.
Installing an additional raceway or cable to a disconnect switch (also referred to as a disconnect or safety switch) after the original installation is not a common practice. A disconnect switch supplies power to one branch circuit or one feeder; adding an additional branch circuit or feeder is not an option.
For example, a fused disconnect switch has been installed next to a dry-type transformer. The primary side of the transformer is supplied by the disconnect switch, and a main-breaker panelboard is supplied by the secondary side of the transformer. In this installation, dedicated equipment space is required for the panelboard but not for the disconnect switch or the transformer (see Figure 1).
Dedicated equipment space is divided into indoor and outdoor installations. Switchboards, switchgear, panelboards and motor control centers installed outdoors shall comply with 110.26(E)(2)(a) through (c). A substantial amount of the text in 110.26(E)(2) is highlighted with gray shading, but the requirements are actually the same as in the 2014 edition. Before 2017, this section had only two subsections. Some of the text in paragraph (E)(2)(a) has been moved to (E)(2)(b). The first sentence that was in 110.26(E)(2)(a) has been configured into a three-item list. Other than one word that was changed, these provisions are exactly as they were in the 2014 edition.
Switchboards, switchgear, panelboards and motor control centers installed outdoors shall comply with all three requirements in 110.26(E)(2)(a). The first requirement states the equipment shall be installed in identified enclosures. In the 2014 edition, this provision stated the equipment had to be installed in “suitable” enclosures; the word “identified” replaced the word “suitable.”
Article 100 defines “identified” as recognizable suitability for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code requirement. Therefore, switchboards, switchgear, panelboards and motor control centers installed outdoors must be suitable for the specific purpose, function, use, environment, application, etc.
The second requirement under 110.26(E)(2)(a) states the equipment shall be protected from accidental contact by unauthorized personnel or vehicular traffic. The third requirement under outdoor installation requirements states the equipment shall be protected from accidental spillage or leakage from piping systems. Other than being in a list format, these last two provisions are exactly as they were in the 2014 edition (see Figure 2).
The second and third sentences that were in 110.26(E)(2)(a) have been moved and are now 110.26(E)(2)(b). The working clearance space shall include the zone described in 110.26(A). No architectural appurtenance or other equipment shall be located in this zone. The zone described in 110.26(A) is the working space required for equipment operating at 1,000V, nominal, or less to ground and likely to require examination, adjustment, servicing or maintenance while energized. Besides having to be installed in accordance with the requirements in 110.26(E)(2), switchboards, switchgear, panelboards and motor control centers installed outdoors shall also be installed in accordance with the requirements for working space depth, width and height.
For example, a 208V, weatherproof (3R) panelboard has been installed outdoors. The distance in front of this panelboard meets Condition 1 in Table 110.26(A)(1). The panelboard is 14 inches wide and the top of it is 6 feet above grade. In accordance with 110.26(A)(1) and Table 110.26(A)(1), the minimum clear distance in front of this panelboard shall be at least 3 feet. In accordance with 110.26(A)(2), the working space width in front of this panelboard shall be at least 30 inches. In accordance with 110.26(A)(3), the working space shall be clear and extend from the grade to a height of 6½ feet (see Figure 3).
The paragraph for dedicated equipment space has been moved from 110.26(E)(2)(b) to (E)(2)(c). However, the two sentences for outdoor dedicated equipment space did not change in the 2017 edition. The space equal to the equipment width and depth, and extending from grade to a height of 6 feet above the equipment, shall be dedicated to the electrical installation. No piping or other equipment foreign to the electrical installation shall be located in this zone. This requirement for outdoor dedicated equipment space was not in the Code until the 2014 edition. Being able to gain access to outdoor electrical equipment is just as important as being able to gain access to indoor electrical equipment (see Figure 4).
There is a new exception under 110.26(E)(2)(b), but in my opinion, this exception should be under 110.26(E)(2)(c). The terms “structural overhangs” and “roof extensions” were submitted in public inputs as an exception under dedicated equipment space, which at the time was 110.26(E)(2)(b). When the Code-making committee made a statement about this exception, they referenced (b) at the time, though (b) was dedicated equipment space. Code-Making Panel No. 2 also stated that keeping this zone completely clear in outdoor locations is not practical in all cases and wiring methods could be routed through nonstructural overhangs or roof extensions to safely be installed to such equipment.
For example, a 208V, weatherproof (3R) panelboard is installed outdoors. The top of this panelboard is 6 feet above grade. The roof of the building extends beyond the exterior wall by 2 feet. The distance from the top of the panelboard to the roof is 4 feet. Although the space equal to the width and depth of this panelboard does not extend 6 feet above it, this is permissible because the roof extends over this panelboard. In accordance with the exception, structural overhangs or roof extensions are permitted in the dedicated equipment space (see Figure 5).
Next month’s column continues the discussion of electrical installation requirements.