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.

Circuit directory marking language

Are we required to mark a panelboard schedule in more than one language? An inspector asked us to do that, and his reason was that while the present owners speak English, the next owners may not.

No, there is not an NEC requirement to identify each circuit or circuit modification in more than one language. The requirement is in Section 408.4(A) and applies to panelboards, switchboards and switchgear. The field identification is not permitted to be described in a manner that depends on transient conditions of occupancy. This does not mean that the directory must be in multiple languages. A transient occupancy is one that is not permanent and lasts only for a short period of time. This means that an office space, for example, must identify circuits by using office numbers instead of last names, as the latter will be subject to change. It is also important to note that 408.4(B) requires panelboards, switchboards and switchgear in other than one- or two-family dwellings to be permanently marked to identify the source of supply to the panelboard, etc.

TR receptacles in offices

When did the NEC start requiring tamper-resistant (TR) receptacles in business offices? I was quite surprised when we got red-flagged for hallway devices that were not TR.

In the 2014 NEC , the general TR receptacle requirements existed only for dwelling units, guest rooms/suites in hotels/motels and child care facilities. See Section 406.12(A), (B) and (C). In 2017, Section 406.12 was editorially modified into list items with the existing areas covered in list items (1) through (3), and multiple new areas were added, including (4) preschools and elementary education facilities, (5) business office corridors, waiting rooms and the like in clinics, medical and dental offices and outpatient facilities, (6) a subset of assembly occupancies described in 518.2 to include places of awaiting transportation, gymnasiums, skating rinks, auditoriums and (7) dormitory units. A new list item (8) was added in the 2020 NEC for assisted living facilities. The only time a business office is included is where it is directly associated with a clinic, medical or dental office, or outpatient facility.

Sheetrock screws and plastic boxes

Is it permissible to use Sheetrock screws to secure receptacles and switches to plastic boxes? The result is an extremely secure hold on the device. There are tract homes being built locally and the contractor uses Sheetrock screws to save time.

No, Sheetrock or plasterboard screws are not permitted to secure receptacles, switches or other devices to plastic boxes. The general rule is to install devices that are listed, labeled or both in accordance with any instructions included in the listing or labeling.

The manufacturer’s instructions will require the use of machine screws (typically included with the device) for securement. Specific NEC requirements exist for securing flush-type general-use snap switches, dimmers, control switches and receptacles to boxes. These requirements (404.10(B) and 406.5) require that screws used for the purpose of attaching devices to a box must be of the type provided with a listed device, or shall be machine screws having 32 threads per inch or part of listed assemblies or systems, in accordance with the manufacturer’s instructions.

Physical damage protection

Is there a list of conduits that can be used for physical protection? We noted (on drawings) the use of schedule 40 PVC for physical protection of cable assemblies in hallways where motorized carts are used. The plan review stated that we need schedule 80 PVC. Is that right? We cannot find any requirement.

See Section 352.12(C), which prohibits the use of PVC conduit where subject to physical damage unless it is “identified for such use.” Schedule 80 PVC is identified as being capable of providing protection from physical damage. There are multiple NEC requirements that specifically recognize (identify) the use of schedule 80 PVC for protection from physical damage. Two examples include 250.64(B)(2) for protection of grounding electrode conductors, and 300.5(D)(4) for protection of raceways emerging from underground installations. Each of these requirements recognize electrical metallic tubing, rigid metal conduit, intermediate metal conduit, RTRC-XW and schedule 80 PVC conduit as acceptable for protection from physical damage.

Equipotential bonding for pools

How do I bond four points on a permanently installed pool that has no metal parts? The walls, uprights and top collar are all made of a type of plastic material. Since the pool is not metallic and it stands almost 4 feet tall, do I still need the solid No. 8 copper around the outside of the pool? It’s just dirt and grass, and there are no concrete or pavers.

The requirements you are referring to are located in 680.26, Equipotential Bonding. In general, this section requires bonding of conductive pool shells, perimeter surfaces, all metallic components, underwater lighting, metal fittings, electrical equipment and any fixed metal parts. The pool you are referencing is a permanently installed aboveground pool that does not have a conductive pool shell. Cast-in-place concrete, pneumatically applied or sprayed concrete and concrete block with painted or plastered coatings are considered conductive materials due to water permeability and porosity.

Your question is about a nonconductive pool, which does not require the perimeter bonding to be attached to the pool because there are no metal parts to bond to; no reinforcing steel or metal parts exist. See the last sentence of the parent text in Section 680.26(B)(2). The perimeter bonding is required in all permanent pool installations; the perimeter could be concrete, pavers or grass. The installation of a copper ring (as mentioned in your question) is one method of installing the perimeter bonding. In this case, there is no structural reinforcing steel (in concrete) and an 8 AWG bare solid copper conductor that follows the contour of the perimeter surface is permitted.

Only listed splicing devices or exothermic welding are permitted for the solid 8 AWG copper, which must be installed 18–24 inches from the inside walls of the pool at a depth of 4–6 inches below the subgrade. It is likely that there are no bonded parts in direct connection with the pool water, which needs to be bonded. There are many readily available products that place an approved corrosion-resistant conductive surface with at least 9 square inches of surface area in direct contact with pool water at all times.

Using an existing cabinet as junction box

In an existing apartment complex, the panelboards are located in clothes closets. We are renovating these units and want to use the existing panelboard(s) as junction boxes. Is that permitted, or do we need to take out the panelboard and install a standard box?

It is permitted to use an existing cabinet as a junction box, provided the cover completely encloses the conductors spliced within. The finished installation must be approved, meaning that it must be acceptable to the authority having jurisdiction.

Type NM cable in PVC conduit to an island countertop

Is it permissible to use schedule 40 PVC conduit to sleeve Type NM cable to an island countertop in a dwelling unit kitchen that is built on a concrete slab on grade? Essentially, the conduit is indoors, as there are walls and a roof above the kitchen.

No, the installation you described is an NEC violation. See Section 300.5(B), which clearly states that the interior of enclosures or raceways installed underground are considered to be a wet location. The conduit is underground, and the fact that it is under a roof above the kitchen is irrelevant. Underground raceways will always be subject to moisture entry. All conductors, cable or cable assemblies installed in raceways underground must comply with Section 310.10(C) for wet locations. In this case, you could use individual conductors such as THWN or sleeve Type UF cable.

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