Although switchgear must be readily accessible and meet minimum working clearances, the entire workspace need not be readily accessible.
The drawing shows a motor control center in an industrial occupancy, where there will be fork-lift truck traffic nearby. In order to be sure that the trucks wouldn't inadvertently strike the equipment, the owner rigged a removable barrier 2 ft away, with the posts set in over-sized holes so it could be lifted out easily. This way the fork-lift trucks had more room to maneuver in the adjacent aisle. We were questioned as to whether this arrangement violated the NEC.
The EC&M Panel's analysis
We think the arrangement shown is a clever solution to a difficult problem, and we think it complies with the Code. There are two requirements that intersect, the first being that the overcurrent devices used for short-circuit and ground-fault protection in the motor control center must be readily accessible in accordance with Sec. 240-24(a):
(a) Readily Accessible. Overcurrent devices shall be readily accessible.
The term "readily accessible" is defined in Article 100 as follows:
Accessible, Readily: (Readily Accessible.) Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc. (See "Accessible.")
In this case the barrier is not so close or built in such a way that actual access to operate the switches is in question. We agree that if it were, if it were necessary to remove the barrier in order to operate the equipment, then this installation would need to be reconfigured. In general, this must be determined by the local authority having jurisdiction, but as shown we doubt there will be a problem with access. Note that the 2-ft aisle width in front of the motor control center is also acceptable as the minimum width of a doorway into the workspace about large switchgear generally, per Sec. 110-16(c):
(c) Access and Entrance to Working Space. At least one entrance of sufficient area shall be provided to give access to the working space about electric equipment.
For equipment rated 1200 amperes or more and over 6 ft (1.83 m) wide, containing overcurrent devices, switching devices, or control devices, there shall be one entrance not less than 24 inches (610 mm) wide and 6 1/2 feet (1.98 m) high at each end.
Although the questioner didn't give the exact physical size or bus rating of the motor control center in question, we think there is adequate access even if this is large enough to come under the special provisions in the second paragraph of this rule. In an emergency the switches in this motor control center can be reached quickly and without resorting to removing the barrier.
Workspace
The other requirement to be addressed is working clearance in front of this equipment. This is equipment that is likely to require examination while energized, and as such, must meet the minimum working clearances in Table 110-16(a). Furthermore, in accordance with Sec. 110-16(b), that space "shall not be used for storage." As shown in the drawing, the owner has taken steps to ensure that that will be the case, with prominent floor markings to that effect. Indeed, the barrier, with its own marking, probably assists in maintaining compliance with this rule. Nevertheless, the barrier does fall squarely within the workspace required by Sec. 110-16:
110-16. Working Space About Electric Equipment (600 Volts, Nominal, or Less). Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.
(a) Working Clearances. Except as elsewhere required or permitted in this Code, the dimension of the working space in the direction of access to live parts operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall not be less than indicated in Table 110-16(a). Distances shall be measured from the live parts if such are exposed or from the enclosure front or opening if such are enclosed. Concrete, brick, or tile walls shall be considered as grounded.
The general requirements in Sec. 110-16 apply to all succeeding subsections to the extent they would be applicable, including the requirement that workspace be both provided "and maintained." As noted previously, subsection (a) applies to this installation. Therefore, the workspace size must be sized in accordance with the table, and then maintained as such. This is the provision that causes some to question this installation. We think that maintaining a workspace is different than maintaining ready access. Both need to be done, but only the latter requires the sense of immediacy that would disallow a temporary obstruction.
In performing any "examination, adjustment, servicing, or maintenance while energized," as described in Sec. 110-16(a), an electrician will not be doing something for which the amount of time involved in removing the barrier would be a safety issue. This is critical. Any time a Code requirement is applied, those applying that requirement should always try to make sure that they are accomplishing a safety objective.
This is different than disallowing storage uses. If this area is used for storage, it is no longer defined as basically electrical space. Most importantly, the storage can quickly impede ready access to the equipment, which is a definite safety issue. Here that is simply not a problem.
Note that many installations, particularly those outdoors, are placed in specially constructed enclosures that are designed to be compatible with the surrounding architecture. Often residential meter/disconnects are boxed in with similar construction to that of the building. As long as these have doors in front that open to provide the required working clearance when it is required, these arrangements are routinely accepted. We think that removing the barrier in this case is not that much different from opening a door.
Dedicated space
Although this is a motor control center covered in Art. 430, Part H, its installation requirements are found elsewhere, as given in the scope of the article, Sec. 430-1:
430-1. Scope. This article covers motors, motor branch-circuit and feeder conductors and their protection, motor overload protection, motor control circuits, motor controllers, and motor control centers.
Exception No. 1: Installation requirements for motor control centers are covered in Section 384-4.
Exception No. 2: Air-conditioning and refrigerating equipment are covered in Article 440.
The important reference here is in Ex. 1, which sends us to Sec. 384-4:
384-4. Installation. Equipment within the scope of Article 384 shall be located in rooms or spaces dedicated to such equipment. Such space shall include that space described in Section 110-16 and, in addition, shall include an exclusively dedicated space extending 25 feet (7.62 m) from the floor or to the structural ceiling with a width and depth that of the equipment. No piping, ducts, or equipment foreign to the electrical equipment or architectural appurtenances shall be permitted to be installed in, enter, or pass through such spaces or rooms.
This reserves both the area above and below the motor control center and the working clearance areas as dedicated spaces for electrical purposes. The barrier, since it is readily removable, is not an "architectural appurtenance" and not excluded by this requirement. Furthermore, since the barrier's only function is to protect the electrical equipment from physical damage, it clearly isn't foreign to the electrical installation. This is true even though it isn't electrical equipment.
There is, however, a new fine print note (No. 4) that some might be tempted to apply in this case. We are aware that fine print notes are not directly enforceable; however, we are choosing to treat this one in a mandatory way for the purposes of this article because it will appear as mandatory text in the CMP 9 rewrite of this section for the 1996 NEC:
(FPN No. 4): It is not the intent that any of the provisions of this rule or the exceptions thereto allow any equipment to be located in the working space described in Section 110-16. This might seem to exclude everything from the working clearance zone, including the barrier. That was not intended; the note arose from proposals addressing power transformers permanently located under panelboards. The idea was merely to strictly correlate this rule with the requirements in Sec. 110-16, particularly the second paragraph:
In addition to the dimensions shown in Table 110-16(a), the work space shall not be less than 30 inches (762 mm) wide in front of the electric equipment. The work space shall be clear and extend from the floor or platform to the height required by this section. In all cases, the work space shall permit at least a 90-degree opening of equipment doors or hinged panels.
This paragraph was modified in 1993 to make it very clear that the workspace went all the way down to the floor in front of the switchgear, and a transformer is certainly equipment within the meaning of the fine print note. The key word, however, is "equipment." This is defined in Art. 100:
Equipment: A general term including material, fittings, devices, appliances, fixtures, apparatus, and the like used as a part of, or in connection with, an electrical installation.
We think that this definition applies to electrical apparatus and the supporting hardware directly involved therewith. We doubt that it can be applied to a stand-alone construction feature. The effect would be to broaden the scope of the NEC far beyond its intended application, with unforeseen consequences. However, some clarification may be in order, perhaps by adding the word "permanently" ahead of "located" in the note.
Other considerations
This analysis was based on an arrangement essentially as depicted in the drawing on page 88. There was abundant illumination from adjacent sources as provided in Sec. 11016(e), and there was plenty of headroom, actually much more than the 6 1/2 ft required in Sec. 110-16(f). Keep in mind that all such requirements need to be satisfied.
EDITOR'S NOTE:
These answers are given by our panel of experts. I am chairing this panel, and the other panel members include Bill Summers, James Stallcup, and Dan Leaf. The opinion expressed is that of the panel. If a panelist disagrees with the majority opinion, his explanation is printed following the answer. Although authoritative, the answers printed here are not, and cannot be relied on as formal interpretations of the national Electrical Code.