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Rules regarding dedicated space for electrical equipment covered under Article 384 were revised and relocated as Section 110-26(f).  The revised rules have created considerable discussion as to their application.  Code Making Panel No. 9 has responsibility for Article 384 and processed Proposal 9-35 and others related to Section 384-4 during the Code Panel Meetings for the 1999 Code cycle.  Proposal 9-35 was submitted by the National Electrical Code Technical Correlating Committee Task Group on Usability of the NEC.  The proposal by the task group recommended moving Section 384-4 into Article 110.  This proposed action is in line with the objective of the Usability Task Group to locate rules of like nature together. Since Section 110-16 of the 1996 NEC contains rules on working spaces about electrical equipment, locating rules governing the space above and below specific electrical equipment is a logical step. As part of the restructuring of Article 110, Section 110-16 of the 1996 NEC was relocated and re-identified as Section 110-26 in Part B of the 1999 Code and entitled “Spaces About Electrical Equipment ." Part B of Article 110 of the 1999 Code includes provisions for 600 volts, nominal, or less and the rules in former Section 110-16 more appropriately belong there. While the Technical Correlating Committee supported the relocation of Section 384-4 to Article 110, it allowed CMP-9 to retain jurisdiction over the section during the 1999 Code cycle. The final wording resulting from actions taken by CMP-9 on Section 384-4 is located in Section 110-26(f) and titled “Dedicated Equipment Space."

The use of space above electrical equipment has been a topic of discussion for many years.  It is clear that the submitter of the original proposal to add rules to limit what is permitted above equipment covered by Article 384 intended to address the problem of water and other liquids leaking or falling onto electrical equipment.  The original proposal was significantly revised and added as Section 384-2 of the 1981 NEC.  A common interpretation of the general rule and exceptions included in this section is that it covers more than just the protection of equipment from falling liquids.  The general understanding of the requirement for space above electrical equipment is for the installation of cables and raceways.  Prior to the 1990 NEC, there was no maximum height restriction for the space above electrical equipment.  A proposal was submitted for the 1990 Code to limit the maximum height of that space to 6 ½ feet or to the structural ceiling, whichever is lower.  The reason for this proposal was to define a maximum height required to address industrial installations where buildings of high bay construction may be 30 or more feet to the structural ceiling.  CMP-9 accepted the proposal in principle and changed the maximum height required to 25 feet. It is evident that the 25-foot rule is not designed to protect electrical equipment against damage from liquids falling from pipes located above it. Liquids falling from pipes greater than 25 feet above equipment can damage that equipment just as those located less than 25 feet.

It is argued that the space above electrical equipment for the installation of raceways and cables is a design issue and should not be included in the Code.  The NEC does include design considerations but it is necessary to implement important safety provisions. Dedicated space for electrical equipment has a direct effect upon personnel safety. Those who run raceways or cables into existing energized electrical panelboards, switchboards, and motor control have an understanding of the need for adequate space above and below such equipment.  Where one installs raceways of cables into an open energized enclosure and has to perform that work while standing on a ladder in front of that equipment, adequate space is needed for both installation and working clearances. 

A Review of Section 110-26(f) for Indoor Installations
The first paragraph of Section 110-26(f) states “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).”  The equipment covered by Article 384 includes switchboards, panelboards, distribution boards installed for the control of light and power circuits, and battery-charging panels supplied from light or power circuits. This first paragraph indicates two distinctive requirements for this equipment. The first provision is “located in dedicated spaces” and the second is “protected from damage." These distinctive points are in line with the common interpretation that a specific space is dedicated for the equipment and that equipment is to be protected from damage, such as by falling liquids. The exception to the first paragraph of 110-26(f) is the same as the exception to the first paragraph of Section 384-4 of the 1996 NEC.  It permits specific control equipment to be installed in those locations.

Section 110-26(f)(1)(a) states “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. (1.83m) 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. below, shall be permitted in areas that do not have the dedicated space described in this rule.”  (See Figure 1.)

Other than the change from 25 feet to 6 feet, the main paragraph in (a) is the same as the first two sentences in Section 384-4(a)(1) of the 1996 NEC. Provisions covering sprinkler protection and suspended ceiling are located in Section 110-26(f)(1) (c) & (d). The change in the exception is more significant.  The wording “located throughout industrial plants” that followed “equipment” in the 1996 NEC has been deleted.  In addition, “or accidental spillage or leakage from piping systems” was also deleted and similar wording was added in (b) of this section. The deletion of the wording limiting the exception to equipment located throughout industrial plants significantly broadened the coverage of the exception to include all occupancies. It should be noted that this exception applies only in areas that do not have the dedicated space described in (a).  More information on how this exception applies is shown below. 

New subsection (b), entitled ”Foreign Systems” reads “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 electric equipment to the structural ceiling.” (see figure 2)

Several points can be deduced from the new and revised wording in Section 110-26(f)(1)(a) and (b).  The first is that space is to be provided for electrical equipment covered by the scope of Article 384.  That space is identified as the width and depth of the equipment and extends from the floor to a height of six feet above the equipment or structural ceiling, whichever is lower.  This space is dedicated to the electrical equipment.  Nothing foreign to the electrical installation is to be installed in that dedicated space. The exception to (a) identifies several conditions, such as height, enclosures, or compliance with the “foreign systems” rule in (b) as being “permitted in areas that do not have the dedicated space described in this rule."

There is a prevalent interpretation that the reference in the exception to (b) permits piping systems foreign to the electrical system to be installed within the dedicated space where protection is required, and permits such systems to be installed immediately above the electrical equipment if a protective barrier is installed that protects the electrical equipment.  A more detailed review of the rules and how they interact does not seem to support that interpretation.  Panel and submitter statements, as well as the final division of this section into “dedicated electrical space” and “foreign systems” appear clearly that two distinctive rules apply here.  The first rule is that dedicated space is required for the electrical equipment. This space is a maximum of six feet or to the structural ceiling, whichever is lower. This space is intended for the installation of cables and raceways associated with the electrical equipment. The second rule permits foreign systems above the electrical equipment but only where protection is provided to protect the electrical equipment.  Foreign systems are not permitted above the electrical equipment regardless of how high they are located unless such protection is provided. Where protection is not provided, the space defined by the second rule extends from the top of the electrical equipment to the structural ceiling.

The two rules cover very different aspects of the installation and stand alone.  The space requirement for the installation of raceways and cables is needed.  Where either space above electrical equipment is unobstructed to the ceiling or to a height of six feet, or where foreign systems are installed and protection is provided, wiring space above the electrical equipment is important.  The rule in subsection (b) that prohibits any foreign system from being installed over electrical equipment is permitted to have an exemption where the electrical equipment is protected from condensation, leaks, or breaks in such systems.  That exemption does not affect the requirement for space above and below the electrical equipment dedicated to the electrical system.  Section 110-26(f)(1)(a) reveals that it does not appear to affect the main rule in (a) in most cases. Those conditions stated in the exception are dependent upon the last part of the exception which reads “shall be permitted in areas that do not have the dedicated space described in this rule.” 

Under the provisions of subsection (a), where the distance from the electrical equipment to the structural ceiling is greater than six feet, the maximum dedicated space required is six feet.  Where the ceiling is less than six feet above the electrical equipment, that height is the maximum required under this rule.  As an example, where the structural ceiling is located three feet above the electrical equipment, that three-foot space complies with the main rule in this section.  The exception does not apply because that area does have the dedicated space described in the rule.  The exception only applies to areas that do not have the dedicated space.  If the contention that foreign systems can be installed immediately above the electrical equipment where protection is provided is true, there is no need for subsection (a).  Either the space is needed or it is not.  It does not seem logical to require the dedicated space defined in (a) if nothing is installed above the defined space but to waive the requirement if protective steps are taken and water piping is installed immediately above the equipment that effectively eliminates cable and raceway entry into the enclosure from above.

CONCLUSION
In summary, a minimum space is required above electrical equipment within the scope of Article 384. That space is defined as being the width and depth of the equipment and extending from the floor to a height of six feet above the equipment or to the structural ceiling, whichever is lower.  No piping or similar systems are permitted to be installed within that area.  That area is dedicated to the equipment and is for the installation of cables and raceways.  Foreign systems containing water or other materials that could damage the electrical equipment located beneath it should leaks or breaks occur in the system or condensation form on those systems that could fall on the equipment are prohibited from being installed within a space equal to the width and depth of the electrical equipment extending to the structural ceiling.  Where protection is provided to keep the electrical equipment from being damaged by such falling products, such systems may be installed above the electrical equipment, but not within the space described in the main rule in (a).  The wording in Section 110-26(f)(1) effectively designates two basic rules and neither rule overrides the other.  The dedicated space rule stands on its own merits as does the rule covering the protection from foreign systems.  It is evident that some changes need to be made to Section 110-26(f) for the 2002 NEC.  This issue will be addressed by CMP-1 for the 2002 cycle and it is expected that several proposals will be submitted to amend the section.  I am confident that good proposals will be submitted; that CMP-1 will handle the issue in an equitable manner; and that the final result of the consensus code change process will be a product that is clear, understandable, enforceable, and reasonable. 

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