In the 1999 National Electrical Code (NEC), Section 110-26, Spaces About Electrical Equipment, consists of 1996 Section 110-16 plus Subsection (f), Dedicated Equipment Space, relocated from 1996 Section 384-4.
“(f) Dedicated Equipment Space. Equipment within the scope of Article 384, and motor control centers, shall be located in dedicated spaces and protected from damage as covered in (1) and (2).
Exception: Control equipment that by its very nature or because of other rules of the Code must be adjacent to or within sight of its operating machinery shall be permitted in those locations.
(1) Indoor. For indoor installations, the dedicated space shall comply with the following.
(a). Dedicated Electrical Space. The space equal to the width and depth of the equipment and extending from the floor to a height of 6 ft (1.83 m) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No piping, ducts, or equipment foreign to the electrical installation shall be located in this zone.
Exception: Equipment that is isolated from the foreign equipment by height or physical enclosures or covers that will afford adequate mechanical protection from vehicular traffic or accidental contact by unauthorized personnel or that complies with b., shall be permitted in areas that do not have the dedicated space described in this rule.
(b). Foreign Systems. The space equal to the width and depth of the equipment shall be kept clear of foreign systems unless protection is provided to avoid damage from condensation, leaks, or breaks in such foreign systems. This zone shall extend from the top of the electrical equipment to the structural ceiling.
(c). Sprinkler Protection. Sprinkler protection shall be permitted for the dedicated space where the piping complies with this section.
(d). Suspended Ceilings. A dropped, suspended, or similar ceiling that does not add strength to the building structure shall not be considered a structural ceiling.
(2) Outdoor. Outdoor electrical equipment shall be installed in suitable enclosures and shall be protected from accidental contact by unauthorized personnel, or by vehicular traffic, or by accidental spillage or leakage from piping systems. The working clearance space shall include the zone described in Section 110-26(a). No architectural appurtenance or other equipment shall be located in this zone.”
In addition to being relocated, edited, and provided with new headings, several substantive changes were made to former Section 384-4 when it became Sec. 110-26(f):
(1) The 25 ft. dedicated space was changed from 25 ft. above the floor to 6 ft. above the equipment, but still extending to the floor;
(2) Foreign piping is permitted at any height above the electrical equipment up to the structural ceiling, but only where protection is provided against leaks onto the electrical equipment due to condensation, or breaks in the foreign piping system.
(3) The exception to 110-26(f)(1)(a) formerly applied only to industrial plants, and now applies to any occupancy.
Now to the question of the day: Since the requirements of 110-26(f) are divided into two parts, (1) Indoor and (2) Outdoor, do the indoor requirements apply to an outdoor installation? The division of the requirements and the headings would suggest that the indoor and outdoor requirements each stand alone. That would leave the indoor requirements unenforceable on an outdoor installation, namely the 6 feet dedicated space above the equipment. There are two added requirements under (2) Outdoor: for protection from vehicular traffic; and for protection from accidental contact by unauthorized personnel. The protection from vehicular traffic is just as necessary for an indoor installation where there are lift trucks and/or other industrial vehicles in use, and is covered in 110-27(b).
The protection against accidental contact by unauthorized personnel is unnecessary here, as it is covered in Section 110-27(a).
In any case, both (1) Indoor and (2) Outdoor subsections apply because of the wording in the first sentence of (f), quoted above, which says that (1) and (2) both apply. If that opening sentence had been worded “(1) or (2)” then the question would be appropriate.
SCHWAN is an electrical code consultant in Hayward, Calif. He can be reached at firstname.lastname@example.org.