The safety of maintenance electricians depends on the consideration of adequate workspace around electrical equipment.
For safe equipment operation and maintenance, you must design and install all electrical equipment with “sufficient” access and workspace. In the case of the NEC, sufficient means you must meet certain depth, width, and height requirements as outlined in 110.26. Let’s begin our discussion by looking at workspace requirements.
Workspace. If equipment may require examination, adjustment, servicing, or maintenance while energized, you must install it in a workspace in accordance with items (1), (2), and (3) of 110.26(A). The phrase “while energized” is the root of many debates. Since electric power to almost all equipment can be turned off, one could argue that workspace is never required, but in today’s litigious environment that wouldn’t be a wise move.
• (1) Depth of workspace. You must ensure the depth of the workspace measured from exposed, live parts or from the front of an enclosure is in accordance with the measurements indicated in Table 110.26(A)(1) (Fig. 1 top right). Condition 1 covers installations with exposed live parts on only one side of the workspace. Condition 2 addresses installations with exposed, live parts on one side of the workspace and grounded parts on the other. Concrete, brick, or tile walls are considered grounded. Condition 3 covers installations with exposed, live parts on both sides of the workspace. Workspace is not required in the back or sides of assemblies without renewable or adjustable parts, or where all connections are accessible from the front. Smaller space is permitted by special permission where voltage is no greater than 30VAC or 60VDC.
• (2) Width of workspace. The width of the workspace must be a minimum of 30 in. wide, but no less than the width of the equipment. Measure the width of the workspace from left to right, right to left, or from the centerline of the piece of equipment. In all cases you must make sure the workspace is of sufficient width, depth, and height to permit at least a 90° opening of all equipment doors (Fig. 2 above). It’s acceptable for enclosure workspaces to overlap one another, because it allows equipment to be installed next to each other (Fig. 3 on page 65).
• (3) Height of workspace. The height of the workspace in front of equipment must be no less than 6 1/2 ft, measured from the grade, floor, or platform. This pertains to service equipment, switchboards, and motor control equipment [110.26(E)]. You can locate equipment such as raceways, cables, wireways, cabinets, and panels above or below electrical equipment, but the equipment must not extend more than 6 in. into the equipment’s workspace (Fig. 4 below).
In addition to the workspace requirements noted above, you must also meet the requirements of rule 110.26(B). This section of the Code requires you to always keep a clear workspace around equipment. Thus, this space cannot be used for storage. It is very dangerous for people who service energized parts to be subjected to additional dangers by working around obstacles such as boxes, crates, appliances, and other impediments. This requirement also applies to signal and communications equipment. You must not install signal and communications equipment so as to encroach on the workspace requirements noted for power equipment.
You must also design your installation to meet entrance and exit requirements of the Code. Let’s take a closer look at these requirements now.
Entrance requirements. To provide a safe exit path in case of a fire or explosion, you must provide a clear and unobstructed path to and from the workspace. Per 110.26(C)(1), you must provide at least one entrance of a sufficient area to give access to the workspace around electrical equipment. Check with the AHJ for the local definition of sufficient area.
Large equipment. When working with equipment rated 1,200A or more, and wider than 6 ft, you must provide at least one entrance not less than 24 in. wide and 6 1/2 ft high at each end of the workspace [110.26(C)(2)]. The door to a workspace must open out and be equipped with panic hardware or other devices so it can be opened with little pressure and without the use of hands. Many electrical contractors do not like being responsible for non-electrical requirements like the installation of panic hardware, but this rule is designed to save electricians’ lives.
The Code permits you to install only one entrance as long as the location permits a continuous and unobstructed way of exit travel or where the workspace requirement is doubled and the distance from the equipment to the nearest edge of the entrance is not less than the minimum clear distance specified in Table 110.26(A)(1).
Additional requirements. In addition to the workspace and entrance requirements noted above, you must also take into account illumination, headroom, and dedicated equipment space requirements in your design.
Illumination. The Code requires you to properly illuminate the workspace around service equipment, switchboards, panelboards and motor control centers located indoors. However, in electrical equipment rooms the illumination may not be controlled by automatic means only. A motion detector switch is acceptable if a manual override is provided.
Headroom. The Code requires you to design and install service equipment, panelboards, switchboards, or motor control centers with a minimum headroom of 6 1/2 ft. What do you do when the piece of equipment is taller than 6 1/2 ft? When the height of the equipment exceeds 6 1/2 ft, the minimum headroom must be no less than the height of the equipment. Note that the minimum headroom requirement doesn’t apply to service equipment or panelboards rated 200A or less in an existing dwelling unit.
Dedicated equipment space. All switchboards, panelboards, distribution boards and motor control centers you install must comply with the requirements of 110.26(F)(1) and (2). On an indoor installation, you must dedicate a clear space equal to the width and depth of the equipment extending from the floor to a height of 6 ft above the equipment or to the structural ceiling, whichever is lower. Typically, no piping, duct, or other equipment foreign to the electrical installation can be installed in this dedicated space (Fig. 5 on page 66). However, there are a few exceptions to this rule. If necessary, you can install suspended ceilings with removable panels in this space. You can also place foreign systems above this space, as long as you provide protection for your electrical equipment against hazardous conditions such as condensation, leaks, or breaks in such foreign systems.
Providing appropriate workspace clearances for electrical equipment is mandatory, and for good reason. These requirements are meant to provide a safe work environment for anyone charged with the maintenance and service of energized equipment. Make sure you keep this in mind on your next project.