Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC), Jim will help you solve it. Questions can be sent to codefaqs@gmail.com. Answers are based on the 2014 NEC.


Grounding electrode
conductor termination


We have installed dozens of permanently installed generators in dwelling units for backup power where they experience power loss from the utility due to storms or other reasons. A few systems include an automatic transfer switch, rated as service equipment to handle the entire load. Depending on the area, the inspectors want different termination points for the grounding electrode conductor (GEC) for those systems. In some areas, the inspector allows us to extend the GEC from the existing panelboard. In others, the inspector requires us to install a new GEC without a splice. What does the NEC actually require? We are splicing on the terminal bar provided. Is that sufficient? Do we need to install a new GEC directly to the service-rated transfer switch?


Article 250 provides prescriptive requirements for the GEC installation. Section 250.24(A)(1) requires the GEC to be connected to the service-supplied grounded conductor at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to the terminal or bus to which the grounded service conductor is connected at the service disconnecting means. This requirement clearly mandates the GEC to be terminated in the service-rated automatic transfer switch.


The general rule in Section 250.64(C) requires the GEC to be continuous (without splice or joint) in this application. Where a splice is necessary, there are four options: (1) a splice is permitted if using an irreversible compression type connector that is listed as grounding/bonding equipment or the exothermic welding process is used; (2) connection through sections of busbar; (3) bolted, riveted or welded connections to structural steel; and (4) bolted flange connections to metal water pipe.


The NEC does not permit GEC extension by termination of the conductor on the grounding terminal bar in the existing panelboard. The permission in 250.64(C)(2) is for busbar, not a terminal bar. In your situation, it seems the only feasible options are to run a new GEC, use irreversible compression-type connectors to splice or use exothermic welding to splice. Once the termination point for the GEC is moved from the existing panelboard to the new automatic transfer switch, the grounded conductors in the panelboard are no longer permitted to be in contact with the panelboard or the equipment grounding conductors (EGCs). The main bonding jumper (MBJ) in the panelboard must be removed. The Code permits a wire-type MBJ or a green screw that runs through the grounded conductor terminal bar to the panelboard. In addition, all EGC terminations on the terminals with grounded conductors must be separated onto terminal bars and bonded to the panelboard. See Section 250.24(A)(5).


AFCI options?


I continue to scratch my head and wonder what options really exist in 210.12(A)(1). We are always looking to improve our work quality and cost-efficiency. At first glance, there seems to be six options to provide arc-fault circuit interrupter (AFCI) protection, but it gets confusing. It seems that two of the options do not even exist. Where do I buy a supplemental arc protection circuit breaker? Where do I find a combination of a branch-circuit overcurrent device and an outlet branch-circuit AFCI that are listed as a combination? We have not been able to find any of these to price; in fact, the supply houses have no idea what we are talking about. Why does the NEC do this?


You are correct. While Section 210.12(A) offers six options for AFCI protection, two of them are not available. During the 2014 NEC revision cycle, the technical committee responsible for these requirements worked diligently to increase the installer’s options. The option provided in Section 210.12(A)(3) permits a listed supplemental arc protection circuit breaker in combination with a listed outlet branch-circuit type AFCI to be installed under the conditions provided. There was a movement to develop a product standard to address a supplemental arc protection circuit breaker, but no listed devices are available.


The option provided in Section 210.12(A)(4) permits a branch-circuit overcurrent device and an outlet branch-circuit type AFCI where they are a listed combination. No listed combination AFCIs are available. During the 2014 revision cycle, both of these options seemed to have merit. They were included in the 2014 NEC to allow manufacturers to pursue a listing and get new products on the market. Unfortunately, that did not occur. Both of these issues are in play in the 2017 revision cycle, and we may see significant changes in Section 210.12.


Wet location?


We recently installed 75 light standards in a parking lot. During the final stages of the project, the electrical inspector asked to look at the branch-circuit terminations in one of the fixture poles. We used standard wire nuts inside the handhole at the base of the fixture pole. The inspector insisted on wire nuts rated for a wet location in each fixture pole. We disagreed completely, but, due to schedule requirements, we replaced all of those wire nuts with a type listed for use in wet locations. This seems to be overkill. Do we also need to use wire nuts rated for wet locations inside every lighting fixture mounted outdoors?


Part IV of Article 410 includes requirements for the support of luminaires (lighting fixtures). Section 410.30(B) recognizes metal or nonmetallic poles as both a means of support for lighting fixtures and as a raceway. In addition, this section requires a handhole in the pole or pole base to have a cover suitable for use in wet locations. Section 300.9 mandates that the interior of all raceways installed above grade in wet locations are considered a wet location. The rule in 300.9 applies to all raceways installed above grade in wet locations including the pole supporting a lighting fixture that is used as a raceway. All conductors, including conductor types marked “W” for wet locations, must be installed in accordance with 310.10(C). The question that remains is the splice. 


The rules in place in the NEC specifically address the conductors installed but not the splice. An example of where a splice is required to be approved for a wet location is in an underground location as seen in Section 300.5(B). In your installation, the NEC does not require splices to be approved for a wet location. It is interesting that, during the public input stage for the 2017 NEC, there is a proposed revision in 410.56(D) to require splices to be listed for damp or wet locations. A similar action for other wet location splices in junction boxes, etc., did not occur.


Fine-stranded wire terminations


Do all fine-stranded conductor terminations require special compression-type connectors? During a solar photovoltaic (PV) installation, we learned that the NEC contains such a rule. On the engineer’s drawings, there was a note that required conductors with more strands than Class B or C type conductors to be terminated only with special compression connector types listed for the cable type. The engineer said it was a requirement for all PV systems. We were not able to find the requirement in Article 690. Does this apply to all conductor sizes?


The engineer was referencing a general requirement that applies to all conductors more fine-stranded than Class B and C stranding. This requirement is not limited to solar PV installations and applies to all installations of fine-stranded conductors and cables without regard to conductor size. Article 690 specifically references the general rule. Section 690.31(H) requires flexible, fine-stranded cables to be terminated only with terminals, lugs, devices or connectors in accordance with Section 110.14, which contains the general rule. Connectors and terminals for these fine-stranded conductors are required to be identified for the specific conductor class or classes.


The general rule in Section 110.14 sends the Code user to Chapter 9, Table 10, to determine if a cable is more finely stranded than Class B or C. For example, consider a 250 kcmil copper conductor. In Class B, there would be 37 strands and, in Class C, there are 61. If we consider a 250 kcmil copper conductor in Class D power-type cabling, where extra flexible stranding is required, there will be 91 strands, and the conductor must be terminated in a connector or terminal identified for Class D. There is no general requirement that the connector be of the compression type. The requirement is that the connector or terminal be identified for the conductor class.