Requirements for Electrical Installations
110-26 Spaces Surrounding Electrical Equipment
Section 110-26 of the National Electrical Code provides working space requirements around electrical equipment operating at 600 volts, nominal or less to ground. Working space must exist around all electrical equipment to allow unobstructed equipment access, safe operation, and maintenance. [110-26]
While Sections 110-26(a) through (d) do not specify any particular type of equipment, Section 110-26(e) is limited to service equipment, switchboards, panelboards, and motor control centers. In combination, subsections (a) through (e) contain specifications relating to: Working Space; Clear Spaces; Access and Entrance to Working Space; Illumination; and Headroom respectively. Subsequently, Section 110-26(f), Dedicated Equipment Space, further defines the type of equipment involved.
110-26(f) Dedicated Equipment Space
Unlike working space requirements, which address the specific needs of personnel, dedicated equipment space relates solely to the equipment's own boundary requirements.
Motor control centers and equipment subject to Article 384, must not only be located within dedicated spaces, but must also be protected from damage. The scope of Article 384 covers all switchboards, panel boards, and distribution boards controlling light and power circuits, as well as battery-charging panels supplied from light or power circuits.
Of equal importance to this section's requirements for physical protection of equipment is that of Section 110-27(b). Here enclosures, or guards, are required for electric equipment located in areas exposed to potential physical damage. The mandatory protective features must be of such strength and so arranged as to prevent damage. Control equipment, which must be adjacent to, or within sight of, its operating machinery, whether due to its very nature or due to the application of other NEC rules, is permitted within the dedicated equipment space. [110-26(f) Exception] Dedicated equipment space is subdivided into indoor and outdoor locations.
110-26(f)(1) Indoor Dedicated Equipment Space
The dedicated equipment space, for indoor installations, must comply with Section 110-26(f)(1)(a) through (d). In order of appearance, these four sections include: Dedicated Electrical Space, Foreign Systems, Sprinkler Protection, and Suspended Ceilings. Care must be taken to comply with the requirements of all four sections (a through d). Upon first reading, it might appear that foreign systems are permitted within the dedicated equipment space as set forth in (a). That, however, is not the case. The requirements of "(b) Foreign Systems" do not override those found in "(a) Dedicated Electrical Space. " A space equal to the equipment's width and depth (commonly referred to as the equipment's footprint), beginning at floor level and extending to a height of 6 feet above the equipment, or to the structural ceiling (whichever is lower), is dedicated to the electrical installation.
No piping, ducts, or equipment foreign to the electrical installation can be located within this zone. Systems foreign to the electrical installation are not permitted below the electrical equipment, nor above in cases where the structural ceiling is within 6 feet of the top of the equipment.
If the structural ceiling is more than 6 feet above the equipment's top side, an area exists above the dedicated space which, by way of an exception and under certain conditions, may contain foreign systems within the equipment's footprint. Equipment isolated from the foreign equipment by height, physical enclosures (or covers) affording adequate mechanical protection from vehicular traffic, from accidental contact by unauthorized personnel, or which complies with (b), is permitted in areas that do not have dedicated space as described in this rule.
This exception permits piping, ducts, foreign equipment, and other similar items within the electrical equipment's footprint, provided the location of same is outside the 6 foot dedicated space. Piping, ducts, foreign systems, etc., which could damage electrical equipment by means of condensation, leaks, or breaks, must meet additional requirements.
The space equal to the equipment's width and depth must remain unobstructed of foreign systems unless protection is provided to avoid damage from condensation, leaks, or breaks in such foreign systems. [110-26(f)(1)(b)] Without protection, no foreign systems are permitted above panelboards, switchboards, and motor control centers.
A drip pan, shield, or other suitable protection can be installed between the electrical equipment and the foreign system. No detailed description of the extent of protection is provided. Be aware that state or local jurisdictions may impose additional requirements pertaining to this issue. Protected piping, ducts, and similar items are permitted above electrical equipment, but only outside of the dedicated electrical space. This dedicated electrical space is the equipment's footprint, starting at the top of the electrical equipment upward to a height of 6 feet.
Two additional regulations pertain to indoor dedicated equipment space (i.e., Sprinkler Protection and Suspended Ceilings). Sprinkler protection is permitted for the dedicated space where the piping complies with Section 110-26(f)(1). [110-26(f)(1)(c)] Although sprinkler pipe is not permitted within the 6 foot dedicated space directly above the electrical equipment, it is permitted above the dedicated space where properly protected.
Section (d) effectively clarifies the meaning of the term structural ceiling. In essence, it states that a dropped, suspended, or similar ceiling not adding strength to the building structure is not a structural ceiling. [110-26(f)(1)(d)] Again, dropped, suspended, or similar ceilings are not structural. In fact, any ceiling which does not lend strength to the building framework is likewise not a structural component.
110-26(F)(2) Outdoor Dedicated Equipment Space
Outdoor electrical equipment must be installed within suitable enclosures providing protection from vehicular traffic, from accidental contact by unauthorized personnel, and from piping systems spills or leaks. [110-26(f)(2)] The zone described in Section 110-26(a) is included in the minimum outdoor working space.
Dependent upon the applicable condition, depth of the working space is either 3, 3 1/2, or 4 feet. [110-26(a)(1)] Minimum working space width is 30 inches. [110-26(a)(2)] Working space height (or headroom) must be at least 6 1/2 feet. [110-26(a)(3)] No architectural appurtenance or other equipment can occupy this zone. One final reminder: Section 110-26(f) regulations apply only to motor control centers and equipment within the scope of Article 384.
Miller, owner of Lighthouse Educational Services, teaches custom-tailored classed and conducts seminars covering various aspects of the electrical industry. He is the author of Illustrated Guide to the National Electrical Code®. For more information, visit his Web site at www.charlesRmiller.com. He can be reached at (615) 333-3336 or charles@charlesRmiller.com.
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