Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at [email protected]. Answers are based on the 2020 NEC .

NEC arrangement

Why are swimming pools in Article 680 and marinas in Article 555? The hazards are basically the same with rules to protect people from electrical hazards magnified by the presence of water. And why don’t we have separate chapters in the NEC for conduits, cable assemblies and one for other distribution means such as busways? I think that would help those of us without formal Code training.

Section 90.3 very clearly states that the NEC  is divided into the introduction and nine chapters. Chapters are broad in scope and the articles within complete that scope. The rules in chapters 1 through 4 apply everywhere, including but not limited to dwelling units, commercial occupancies, industrial installations, marinas, healthcare facilities and many more. Chapters 5, 6 and 7 apply to special occupancies, special equipment or other special conditions and supplement or modify the requirements in Chapters 1 through 7.

This means that the requirements in chapters 5–7 very simply contain modifications to general requirements or supplemental requirements. Chapter 8 stands alone and is not subject to the requirements of chapters 1–7 unless there is a specific reference to a requirement in Chapter 8. Chapter 9 consists of tables that are applicable as referenced.

Marinas are properly located in Chapter 5 for special occupancies, and swimming pools are properly located in Chapter 6 for special equipment. A marina is an occupancy because I can live there in a houseboat. I cannot live in a swimming pool, so it is not an occupancy.

The requirements in Article 680 cover the electrical equipment and installation of a swimming pool. We can install a swimming pool at a marina and a backyard, but you cannot install a marina in a typical dwelling unit backyard.

The scope of Chapter 3, “Wiring Methods and Materials,” contains everything we need with respect to getting current flow from point A to point B with all of the permitted wiring methods and materials. Separating this into three chapters would be extremely problematic. Article 300 contains general requirements for wiring methods and materials followed by articles to cover all cable assemblies, boxes, conduit, busways and much more in an extremely logical format.

The arrangement of the Code works incredibly well and tinkering with it would destroy the sensible order and usability of the NEC. If an untrained user cannot use the NEC in its current format, they will continue to fail in a new arrangement. Section 90.1 explains the purpose of the NEC, and the last sentence is, “This Code is not intended as a design specification or an instruction manual for untrained persons.”

Triplex/quadruplex, permitted uses?

We just received multiple OSHA citations for using quadruplex to feed a temporary panelboard. We have always used triplex and quadruplex for temporary feeders. Yes, we should have transitioned to SER cable to enter the panelboard, but, in general, we believe that triplex and quadruplex are permitted by the NEC as seen in articles 396 and 398. Can you help us document that by providing the applicable requirements?

No. In this case, OSHA is correct; the use of triplex and quadruplex as a feeder violates both OSHA and NEC requirements. It is important to understand that standard triplex and quadruplex as installed by electric utilities as service drops do not contain insulated conductors because they are covered. Article 396 provides requirements for messenger-supported wiring. The only time that the NEC references a permitted use for these products is in Section 396.2 in the definition of insulated conductor. This definition applies only within Article 396. The definition recognizes conductor types described in 310.4 as insulated conductors and recognizes conductors encased in a polymeric material that has been evaluated for the applied nominal voltage as insulated conductors only where they are used as overhead service entrance conductors. This is a very common-sense recognition of a permitted use.

Utilities have been using triplex and quadruplex as service drops for decades without an issue. There is, however, a need to modify the permitted wiring methods for services in 230.43 as there is no permission to use a messenger cable encased in a polymeric material that has been evaluated for the applied nominal voltage. The only way you can get there with the present requirements is through 230.43(7) with a service entrance conductor assembly, defined in 338.2, which could be multiple single conductor type USE cables with a messenger cable.

Getting back to general permitted use of these assemblies as a feeder or branch circuit, it is extremely important to note that all current-carrying conductors are required to be insulated, see 310.3(D). With specific focus on temporary wiring, see 590.4(B) that prohibits triplex and quadruplex, and the only reference to single conductors is in the exception that permits single insulated conductors for emergencies and tests. These installations typically consist of flexible cords (see 400.4) and single-pole separable connectors (see 406.13).

Articles 396 and 398 do not permit these assemblies to be used as feeders or branch circuits. The definition of messenger-supported wiring (396.2) references factory-assembled and twisted multiplex cables using a bare conductor, such as triplex or quadruplex that consist of one or more insulated conductors. See the definition of open wiring on insulators (in 398.2) that is defined as a method to support single insulated conductors run in or on buildings and is limited by 398.10 to use in only industrial or agricultural establishments on systems of 1,000 volts, nominal or less.

The NEC does not have a blanket listing requirement. However, OSHA requires all conductors, equipment and material used in a temporary installation to be listed or field-evaluated. Triplex is not listed. Serious OSHA fines start at $13,260 and can escalate significantly with repeat or willful violations.

Line voltage replacement LED tubes

Does the NEC permit 2-by-4 lay-in-type fixtures to be upgraded with line-voltage replacement LED tubes? We have installed kits that upgrade the ballast, reflector, etc., but the line-voltage tubes are new to us. A client wants us to install a product that is UL-classified but not listed. It is marketed as a replacement for conventional fluorescent lamps.

The NEC permits an existing fixture to be upgraded with line-voltage LED tubes that are classified, provided that they have a classification mark and are part of a listed, “LED LUMINAIRE RETROFIT KIT” or something similar. There are multiple requirements that affect this installation. Section 410.6 requires all luminaires, lamp holders and retrofit kits to be listed. The line-voltage LED tubes may be classified, but the retrofit kit must be listed. The general rule in Section 410.7 prohibits luminaires from being reconditioned. However, if a listed retrofit kit is installed in a luminaire in accordance with the installation instructions, the retrofitted luminaire is not considered reconditioned.