As stated in 90.1(A) of the National Electrical Code (NEC), the purpose of the Code is the practical safeguarding of people and property from hazards arising from the use of electricity. However, complying with NEC rules and regulations will not necessarily provide an installation that is efficient, convenient or adequate for good service or future expansion of electrical use.


For example, an electrical service is needed for a small industrial occupancy. A load calculation for this occupancy was performed in accordance with Article 220, and the minimum size service was 388 amperes (A). In accordance with Table 240.6(A), the next standard ampere rating above 388A is 400A. While installing a 400A service would comply with the Code, there would be little room for future expansion of electrical use.


The requirements in Section 110.26 are important, as well, since they contain access and working space provisions. Subtopics in this section include working space, clear spaces, entrance to and egress from working spaces, illumination, dedicated equipment space and locked electrical rooms or enclosures. The subsection “Dedicated Equipment Space” pertains to very specific equipment.


Section 110.26(E) only pertains to switchboards, switchgear, panelboards and motor control centers. This subsection is divided into indoor and outdoor installations. Indoor installations shall comply with 110.26(E)(1)(a) through (E)(1)(d). The first subsection for indoor installations shows the required dedicated equipment space, which is sometimes referred to as the equipment footprint. The second subsection under indoor dedicated equipment space pertains to foreign systems. The area above the dedicated space required by 110.26(E)(1)(a) shall be permitted to contain foreign systems, provided protection is installed to avoid damage to the electrical equipment from condensation, leaks or breaks in such foreign systems [110.26(E)(1)(b)].


This does not mean it is OK for the area above the electrical equipment to contain foreign systems. The area mentioned in this subsection is the area above the dedicated equipment space. The dedicated space is 6 feet above the top of the equipment unless there is a structural ceiling; then the dedicated space is up to the structural ceiling. If the structural ceiling is 6 feet or less above a switchboard, switchgear, panelboard or motor control center, no foreign system would be permitted in this zone. Foreign systems can be installed above the 6-foot zone, but if there is a possibility the electrical equipment could be damaged from condensation, leaks or breaks in such foreign systems, some type of protection has to be installed. The protection can be fairly simple, such as wrapping an HVAC duct with insulation to avoid condensation. 


For piping containing liquids, a drip pan installed below the piping could protect the electrical equipment in the event of leaks or breaks. For example, the distance from the top of a panelboard to the structural ceiling is 8 feet. A copper plumbing pipe has been installed above the panelboard and above the 6-foot dedicated equipment space. To protect the panelboard from possible leaks in the plumbing pipe, a drip pan has been installed above the panelboard under the pipe. Like the plumbing pipe, the drip pan has been installed above the panelboard’s 6-foot dedicated equipment space. Because the plumbing pipe and drip pan have been installed above the dedicated equipment space and leak protection has been installed, this installation is permitted (see Figure 1).


A foreign system as mentioned in 110.26(E)(1)(b) is any system that is not directly related to the electrical system. Raceways, junction boxes and troughs containing electrical conductors are not foreign to the electrical system and, therefore, can be installed within the dedicated equipment space. Items such as HVAC ducts, gas pipes, water pipes and drain pipes are foreign to the electrical system and, therefore, shall not be installed within the dedicated equipment space. Leak protection, such as a drip pan, shall not be installed within the dedicated equipment space either.


For example, the distance from the top of a panelboard to the structural ceiling is 7 feet. A copper plumbing pipe has been installed above the panelboard and above the 6-foot dedicated equipment space. To protect the panelboard from possible leaks in the plumbing pipe, a drip pan has been installed under the pipe above the panelboard. This drip pan has been installed less than 6 feet above the top of the panelboard and, therefore, is within the panelboard’s dedicated equipment space. Because the drip pan has been installed within the dedicated equipment space, this installation is not permitted (see Figure 2).


The third subsection under indoor dedicated equipment space pertains to sprinkler protection. Like the requirements for foreign systems, sprinkler protection can be located above the 6-foot zone, but there has to be some type of protection from condensation, leaks or breaks. This is not saying fire sprinkler heads cannot be installed to protect electrical equipment; sprinkler protection (such as a fire sprinkler pipe) can be located above the 6-foot zone, but there has to be some type of protection from condensation, leaks or breaks.


For example, the distance from the top of a panelboard to the structural ceiling is 8 feet. A fire sprinkler pipe has been installed above the panelboard and above the 6-foot dedicated equipment space. To protect the panelboard from possible leaks in the pipe, a drip pan has been installed under the pipe above the panelboard. The drip pan has also been installed above the panelboard’s 6-foot dedicated equipment space. Sprinkler heads have been installed to protect the electrical equipment, but no heads have been installed directly above the panelboard’s footprint. Because the sprinkler pipe and drip pan have been installed above the dedicated equipment space and leak protection has been installed, this installation is permitted (see Figure 3).


The fourth subsection under indoor dedicated equipment space pertains to suspended ceilings. Having a suspended ceiling located above a panelboard and within the 6-foot zone does not mean systems foreign to the electrical installation can be installed above the suspended ceiling. A suspended ceiling is not considered a structural ceiling. As stated in 110.26(E)(1)(d), a dropped, suspended or similar ceiling that does not add strength to the building structure shall not be considered a structural ceiling. Although the framing for the suspended ceiling could be installed so the electrical equipment’s footprint above the equipment remains open, it may not be necessary. In accordance with the exception to 110.26(E)(1)(a), suspended ceilings with removable panels shall be permitted within the 6-foot zone. 


For example, a panelboard has been mounted on a concrete block wall. The structural ceiling is 6 feet above the top of the panelboard. A suspended ceiling is 2 feet above the panelboard. The suspended ceiling is within the panelboard’s footprint, but there are removable panels in the suspended ceiling. The suspended ceilings can be installed within the 6-foot zone because it has removable panels (see Figure 4).


Next month’s column continues the discussion of electrical installation requirements.