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. Send questions to email@example.com. Answers are based on the 2017 NEC.
Premises-powered broadband communications
At a recent presentation I attended, the speaker mentioned premises-powered broadband communications systems and said they were becoming the norm for dwelling units in our area. Are they covered by the NEC ?
Yes, in Article 840, “Premises Powered Broadband Communication Systems.” These systems do not have power supplied by the utility to the building like older phone circuits were powered by the utility to ring the phone. These new systems bring only a broadband signal to a network terminal through optical fiber, twisted pair or coaxial to the building. Power for the network terminal is supplied by the premises and may be a receptacle outlet for the equipment to plug in to. The network terminal, powered by the premises then converts the broadband signal into telephone, high-speed internet, TV and other interactive services. There are significant revisions in the 2020 NEC that will permit circuits to leave the building and power remote equipment.
Grounded conductor identification
It is my understanding that all smaller grounded conductors must be white or gray. Another contractor is installing smaller individual grounded conductors on the roof in a PV system, and they are identifying grounded conductors with white tape at terminations. Does the NEC permit this?
Yes. Section 200.6 provides requirements for identifying grounded conductors. 200.6(A) addresses grounded conductors that are sizes 6 AWG or smaller. This requirement includes eight list items describing permitted identification methods. While list items (1) and (2), which require a continuous white or gray outer finish are the most often applied, there are other permitted methods. List item (6) permits a single conductor used as a grounded conductor in a PV system that is sunlight-resistant and outdoor-rated to be identified at the time of installation with a distinctive white marking at all terminations.
Batteries and ESSs
Does Article 706, “Energy Storage Systems,” apply to all installations of batteries?
No. The scope of Article 706 clarifies that it only applies to permanently installed ESSs that operate at over 50 volts (V) AC or 60V DC that may be stand-alone or interactive with other electric power production sources. An ESS is made up of one or more components that are assembled together and capable of storing energy for use at a future time. ESSs are not limited to batteries. These systems may include capacitors and kinetic energy. ESSs may have an AC or DC output for utilization and may include inverters and converters to change stored energy into electrical energy. ESSs are intended to store and provide energy during normal operating conditions. Just because a battery may store energy, it is not necessarily an ESS. Part III of Article 706 contains requirements for Electrochemical Energy Storage Systems. This part applies to batteries that are not components within a listed product. An informational note to Part III explains that energy storage components integrated into a larger piece of listed equipment is an example of components within a listed product. It is important to note that Article 480 applies to all installations of storage batteries including those that may be part of an ESS.
Tentative Interim Amendments, do they apply to me?
We are currently using the 2017 NEC in our state. We are aware of TIA 17-8 that deleted list item (3) that addressed healthcare occupancies in section 700.10(D). This will impact a project that we are working on. Does that TIA apply automatically or does the state need to adopt it?
I suggest that you contact your AHJ and discuss how your state adopts the NEC . If they have a disclaimer that omits any amendments to the 2017 edition, the TIA may not apply in your state at this time. TIAs become effective immediately upon issuance by the NFPA Standards Council. TIA 17-8 was issued by the council on Dec. 6, 2017. See the informative text in the NEC just before Article 90. This text clarifies that the NEC in effect consists of the current edition and all TIAs and errata in effect. NEC users can very easily locate all TIAs and errata for the edition of the Code they are using by going to nfpa.org.
Attachment plug required?
An inspector refused to accept the use of flexible cord (Type SJOW) for connection to mobile freezers in a commercial kitchen. We had them hard-wired to eliminate the need for GFCI protection. The inspector required us to install an attachment plug and a GFCI protected receptacle. Doesn’t 400.10(A)(3) permit this installation?
When designing an essential electrical system in a healthcare facility, selective coordination is only required for a fault that will occur beyond 0.1 second. Can the same be applied for emergency systems that are not part of a healthcare facility? I cannot find a similar reference to a time frame for other selective coordination requirements.
No. Section 700.32 requires that emergency system overcurrent protective devices (OCPDs) be selectively coordinated with all supply-side OCPDs. The requirement that you are referring to is in section 517.31(G) Coordination. It is extremely important to note the title of this section. This is not selective coordination. This permissive requirement is for coordination purposes only and allows for a six-cycle overlap of OCPD clearing times, which will allow a cascading outage to occur. The term “selective coordination” is defined in Article 100. It is the localization of an overcurrent condition that will restrict outages to only the circuit or equipment affected. This is accomplished by selecting and installing OCPDs and their ratings for the full range of overcurrents and the opening times associated with any potential overcurrents. OCPDs that are selectively coordinated will limit an outage to the circuit or equipment that is involved in a fault, or a single OCPD will open. Where there is an overlap of OCPD clearing times, a fault may open multiple upstream OCPDs, which will cause an outage in equipment and circuits that were not affected by the fault.
Are handholes required to be listed? Do we need to enter through a sidewall with a connector for conduits?
The NEC does not require handhole enclosures to be listed. However, Section 314.30 requires that they be designed and installed to withstand all loads that are likely to be placed upon them. Additionally, handhole enclosures must be identified for use in underground systems. The term identified is defined in Article 100 and the associated informational note explains that suitability (in this case, for use in underground systems) is typically done through listing and labeling by a qualified testing laboratory or by other organizations concerned with product evaluation. An informational note following 314.30 references an ANSI standard on the integrity of the enclosure with respect to loads that are likely to be placed upon them. Raceways entering handhole enclosures must extend into the enclosure but are not required to be mechanically connected. 314.30(C) requires all conductors and any splices in the handhole be listed for wet locations.
Supports over a building
Section 225.15 requires that any outside branch circuit or feeder that is supported over a building be done so in accordance with Section 230.29. This requires substantial structures for support. Additionally, where the support structure is metal (we are using Unistrut), we are required to bond the grounded conductor to the metal support. We are installing SER cable to supply a garage and will be over the building that is service-supplied. Are we required to bond the grounded conductor in the SER feeder to the metal support? How would we do that, by installing a JB?
You have identified a problem that exists in the 2017 NEC . The intent of Section 225.15 was only to securely support. The technical committee referred to 230.29 in an effort to eliminate duplicate text without realizing that the requirement to bond the grounded conductor came along with requirements to securely support. There is no need or reason to bond an outside branch circuit or feeder to a metal support. This has been corrected in the 2020 NEC and 225.15 now requires only that outside branch circuit and feeder conductors passing over a building be securely supported.
Type UF installation
Is it permitted to splice Type UF cable underground?
Yes. Type UF cable is permitted for direct burial in the earth. 340.10(1) Uses Permitted, authorizes type UF cable to be direct buried in accordance with Section 300.5 Underground Installations. 300.5(E) Splices and Taps permits direct buried conductors and cables to be installed underground and spliced or tapped without the use of a junction box. These underground splices or taps must be installed in accordance with 110.14(B), which requires the wire connectors or splicing means installed on conductors for direct burial be listed for that use.