Recently, the question arose about using cords for temporary wiring. It was interesting to watch the reaction and response. It seems there are considerable inconsistencies relative to this subject. Perhaps a practical approach to the National Electrical Code (NEC) application for such installations will help. So, let’s start with the basic question and a simple answer: Can multiconductor cords be used for temporary power and lighting installations? In a word, yes, and the Code provisions can substantiate the answer.
Code arrangement and application
It is important to have a good general understanding of how the NEC is arranged and how it is intended to apply to installations and systems, covered nicely in Section 90.3. The Code has an introduction and nine chapters. Chapters 1 through 4 apply generally, while chapters 5, 6 and 7 apply to special occupancies, special equipment and special conditions, respectively. Chapter 8 covers communications systems and is not subject to the requirements in chapters 1 through 7 unless there is a reference to the rules from Chapter 8.
Navigating the NEC
To find information in the NEC, use the index. There, find “cords,” under which you’ll find a reference to Article 400 and “Uses Permitted 400.7” and “ Uses Not Permitted 400.8.” The other key phrase in the question is “temporary wiring.” In the index, find “temporary installations” and a reference to Article 590. Under “temporary installations,” there are more specific references to topics such as “all wiring installations” 590.2, “branch circuits” 590.4(C) and “feeders” 590.4(B). With these Code sections identified, proceed to the rules and determine the proper application.
General provisions first
Looking at the uses permitted for flexible cords in 400.7, you’ll find several uses listed in addition to uses specifically permitted elsewhere in the Code as provided in list item (10) to this section. This will factor into the appropriate response to this question. Checking under the uses not permitted items in 400.7, there are several restrictions on using cords for wiring. Cords are generally not permitted to substitute as the fixed wiring of a structure or to run holes in walls, structural ceilings, dropped ceilings, floors and so forth. Section 400.8 also indicates cords are not permitted to be attached to a structure, concealed by the building components or run where they are subject to physical damage. The key here is that all of these restrictions in 400.8 deal with permanent wiring installations and not temporary wiring. We need to apply the additional modifying provisions in Article 590 that cover temporary wiring.
Modification to general rules
Referencing Article 590, notice that the rules in this article apply to temporary power and lighting, so it can apply to the question at hand. Section 590.2 is important in that it clarifies that general requirements in the Code apply to temporary installations unless modified by Article 590. This means conductor sizes, overcurrent protection, grounding, bonding and so forth have to be in accordance with applicable NEC rules. Temporary wiring, as with permanent wiring covered by the Code, is also subject to the approval of the inspector or other authority having jurisdiction (AHJ).
Knowing that cords would be used for branch circuits or feeders, one can reference 590.4(B) and (C) to determine applicability. Referencing both sections, it is clear that cable assemblies and multiconductor cords and cables of a type identified for hard usage as provided in Table 400.4, are permitted for temporary wiring. Here is where an applicable modification to the general provisions in 400.8 takes place. While 400.8 would normally restrict flexible multiconductor cord and cable from being installed as permanent wiring of a building or structure, Section 590.4 permits cord (hard-use and extra-hard-use) for temporary installations as long as it is approved by the AHJ as indicated in 590.2(B). Remember, the type of temporary wiring method used is not expected or required to meet the same requirements as permanently installed wiring methods. It seems appropriate and practical since the installation is not permanent and, as 590.3(D) indicates, must be removed upon completion of the construction or other purpose for which the temporary power was installed.
Temporary wiring is not an “anything goes” situation. The “uses permitted” for flexible cords for electrical installations are covered by the general provisions in 400.7, and these uses are expanded to other specific Code provisions as indicated in 400.7(10). Knowing that Chapter 5 can modify the general requirements of chapters 1 through 4 as provided in 90.3, Article 590 applies to the installation addressed in the question. Section 590.4 clearly indicates that cable assemblies and hard-use or extra-hard-use multiconductor cords and cables are permitted for this type of temporary installation. For additional useful information, refer to NECA-200 2010 Standard for Installing and Maintaining Temporary Electric Power at Construction Sites.