Section 110.26 of the National Electrical Code (NEC) requires specific minimums for working space around electrical equipment. Section 110.26 is divided into six subsections, and some of them contain even more subsections.
The dimension for working space width for equipment operating at 600 volts (V), nominal, or less to ground and likely to require examination, adjustment, servicing or maintenance while energized shall comply with 110.26(A)(2). If the electrical equipment has a width of 30 inches or less, the minimum working space width in front of electrical equipment is 30 inches.
It does not matter if the electrical equipment is flush-mounted or surface-mounted. For example, a flush-mounted panelboard has been installed next to a water heater in a small area. The panelboard is 16 inches wide. In accordance with 110.26(A)(2), the minimum working space width in front of this panelboard is 30 inches (see Figure 1).
If the electrical equipment is wider than 30 inches, the minimum working space in front of the electrical equipment is the equipment width.
For example, a switchboard is located next to a disconnect switch (safety switch). The switchboard width is 52 inches, and the disconnect switch width is 20 inches. The minimum working space width in front of the switchboard is 52 inches, and the minimum width in front of the disconnect switch is 30 inches (see Figure 2).
There is no requirement for the electrical equipment to be in the center of the working space. The electrical equipment could be on the left side of the working space, on the right side, or anywhere in between (see Figure 3).
There is no requirement for each piece of electrical equipment to have its own dedicated 30-inch working space. Equipment can share working space.
For example, two panelboards have been installed about 1 inch apart. Each panelboard is 17 inches wide. The working space for the panelboard on the left can start at the left edge of that panelboard and overlap into the working space of the panelboard on the right and vice versa. Because the working space of one panelboard can overlap into the working space of the other, the working space for these two panelboards can be the width of each panelboard plus the space between them (see Figure 4).
The last sentence in 110.26(A)(2) pertains to the equipment doors and hinged panels. In all cases, the work space shall permit at least a 90-degree opening of equipment doors or hinged panels. If a disconnect switch is installed too close to a wall on the left side or too close to another piece of electrical equipment on the left side, the door will not be able to open at least 90 degrees.
This requirement does not only apply to disconnect switches. Before installing electrical equipment, ensure the equipment doors or hinged panels will be able to open at least 90 degrees.
The dimension for working space height for equipment operating at 600V, nominal, or less to ground and likely to require examination, adjustment, servicing or maintenance while energized, shall comply with 110.26(A)(3). The working space shall be clear and extend from the grade, floor or platform to a height of 61⁄2 feet or the height of the equipment, whichever is greater.
Like the dimension for width of working space, there is a minimum dimension for working space height. If the height of the electrical equipment is 61/2 feet or less, the minimum height shall be 61/2 feet. For example, the height of a panelboard installed on a concrete block wall is 5 feet, 10 inches. The minimum working space height required for this panelboard is 61/2 feet (see Figure 5).
If the electrical equipment height is greater than 61/2 feet above the floor, the minimum working space height in front of the electrical equipment is the equipment height.
For example, a switchboard is located next to a disconnect (safety) switch. Its height is 84 inches (7 feet), and the disconnect switch height is 72 inches (6 feet). Since the switchboard height is greater than 61/2 feet, the minimum working space height required is the switchboard height (7 feet). The minimum working space height required for the disconnect switch is 61/2 feet (see Figure 6).
The minimum working space height for electrical equipment has not always been 61/2 feet. For many years, the working space height (or headroom) was required to be at least 61/4 feet (or 6 feet, 3 inches). The change to 61/2 feet occurred in the 1993 NEC.
Next month’s column continues the discussion of electrical installation requirements.