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A Practical Review of the C2-2017 National Electrical Safety Code

In the June-July 2020 issue of Incident Prevention magazine, I made a mistake in the Q&A. I stated that there is no consensus on a particular procedure when, in fact, there is. It is new in the most recent edition of the National Electrical Safety Code, but I missed it when it was published in 2017. In light of my error, I decided I should take a closer look at the most recent revision of the standard and present my findings here for the benefit of iP’s readers.

The NESC is one of the consensus standards that I regularly recommend as an important resource – every safety professional should have a copy of it in their library. Here’s some important information about the use of consensus standards: First, the standards are more procedural than the OSHA performance language. “Performance language” means that a rule is written in a format that tells the reader what must be accomplished. Procedural language, on the other hand, tells the reader how to accomplish something. Second, OSHA classifies consensus standards into two categories, adopted and referenced. Consensus standards that are adopted are incorporated into the OSHA standards by references listed in 29 CFR 1926.6 for construction and 1910.6 for general industry. Referenced standards are adopted into the OSHA rules with the force of law and can be cited in compliance actions against employers. Consensus standards that are referenced are helpful to the employer, as OSHA puts it in the introduction to Appendix G of 1910.269. OSHA defines “recognized” consensus standards as “helpful in understanding and complying with the requirements contained in § 1910.269. The national consensus standards referenced in this appendix contain detailed specifications that employers may follow in complying with the more performance-based requirements of § 1910.269.” You will find the same referenced standards in Appendix G to the 1926 Subpart V construction standards.

OSHA has taken steps to move away from incorporation of certain consensus standards that were related to the electric utility industry by reference. The agency added in the preamble that notes throughout the rule clarify that OSHA will deem compliance with the consensus standards listed in the notes to be compliance with the performance requirements of the final 1926.97, “Electrical protective equipment.” You can read a detailed discussion on the application of consensus standards related to compliance with OSHA’s performance standards in the preamble to the final rule (see Federal Register Vol. 79, No. 70, Friday, April 11, 2014, page 20327).

About the C2-2017 NESC
Before we move on to the C2-2017 NESC, you should note the goal of the code: to safeguard the public, utility workers and utility facilities. For the purpose of this article, we will only review worker safety measures that changed in the 2017 edition.

Right from the beginning of Section 1, the NESC has revised or added to several rules reflecting OSHA’s latest philosophy that training and supervision are key elements of safe work. While there are numerous design requirements for worker safety, the rules for worker safety are predominantly found in Section 4.

The first paragraph in Section 4 is rule .410, which has new language that requires employers to better train employees on hazards related to communications equipment. There have always been rules requiring safety procedures associated with overhead lines, but these revisions add communications. This is a reasonable addition considering the evolution of 5G and the numerous antenna facilities being mounted on distribution poles and low-level supports near energized lines. Rule .410(A)(4) requires training for employees who work “in the vicinity” of antennas within the 3-kHz to 300-GHz spectrum.

Rule .410(A)(3) has added language to bring the C2-2017 standard more in line with the latest OSHA rules for arc flash and flammability of workers’ clothing.

A previously published Table .410-1 for arc flash protective clothing systems added panel boards fewer than 250 volts and greater than 100 amps. For systems less than 1,000 volts, this table has no equivalent in the OSHA standard and is calculated using IEEE 1584-2002, which is one of the approved methods listed in Appendix E, Table 2. If employers want to use this table in the scenarios listed, pay close attention to the notes referenced below the table. Remember, it is up to the employer to justify and be able to defend the use of Table .410-1 in their individual workplaces.

Paragraph D of Part 411, “Protective Methods and Devices,” added language to ensure that new safety signs and replacement safety signs conform to the latest edition of ANSI Z535.1 through Z535.5. Most notable here is a reminder that agrees with the related OSHA standards. The old but very common red oval “DANGER” sign on a square black field is no longer approved. All safety signs are now required to be a square color field with an alert symbol accompanied by a worded warning message.

Part 411(F)(2) added language making locking snap-hooks mandatory on fall protection equipment. This puts the C2-2017 standard in alignment with OSHA and the ANSI Z359 fall protection equipment standards.

Part 411(K), “Fall Protection,” added language equivalent to that of the new OSHA fall protection standards in 1910.269 and 1926 Subpart V. The notes added to that rule include language useful in developing procedures for implementation of the more performance-oriented OSHA language.

Part 422, “Overhead Line Operating Procedures,” added some recommended safe work practices that can be used to protect employees setting poles in energized circuits. The recommendations here are similar to recommendations made by stakeholders and considered by OSHA in promulgating the recent 2015 final rule. Ultimately, OSHA rejected that proposed procedural language in favor of more performance-oriented language.

In Section 43, “Rules for Communications Employees,” a requirement was added to Rule 431 to ground de-energized supplies to telecommunications equipment, referring the reader to the grounding rules in Section 44. This rule applies to storm restoration, particularly where joint-use facilities may have brought the utility and communications facilities together. The rule previously existed, but in this revision a single word – “themselves” – was added, requiring that the worker servicing storm-damaged equipment assure themselves that the supply lines involved are de-energized and grounded. Most powered apparatuses typically are locally de-energized by removal of a fuse or operation of an integral circuit breaker. This rule requires the technician to assure themselves that nearby storm-damaged supply conductors are safe to approach – through disconnection and grounding by qualified workers – before they proceed with their communications responsibilities.

Section 441, “Energized Conductors or Parts,” is a reformatted and updated section. To bring the standard into agreement with the revised OSHA 2015 final rule requirements, the section begins with revised rules for minimum approach distances, insulation and isolation. As with the preceding rules, this section includes expanded language and procedural recommendations rather than the language used by the related rules in the OSHA standards. 

A Complete Revision
Section 444 of the C2-2017 standard, “De-energizing Equipment or Lines to Protect Employees,” was completely revised, deleting earlier guidance to work between grounds placed close to the work area or to use a work-site ground with various arrangements. The revised rule matches that of the OSHA standard, requiring that “grounds be placed at such locations and arranged in such a manner that affected employees are protected from hazardous differences in electrical potential.”

Rule 444(C)(1) is where you find the procedures for switching and recording switching steps, operation times of switches and workers involved. The rules here reflect the OSHA requirements of 1910.269(m), “Deenergizing lines and equipment for employee protection,” but 444(C)(1) is less detailed than OSHA, with one exception. The OSHA standard has no requirement for keeping a record of the switching operations whereas the NESC does. Note that this standard does not recommend or require a length of time that the records must be kept.

Rule 444(C)(2) includes a new rule, which happens to be the one I missed in the June-July 2020 Q&A. The question was about whether minimum approach distance is the length of an air gap for isolation of distribution voltage. I explained that, no, MAD is a combination of the minimum air insulation distance (MAID) and an inadvertent movement factor also known as the human component. Since an open dropout switch had no movable parts, an inadvertent component was not required, so a dropout or any distribution switch effectively open would suffice as isolation for worker protection. The problem was that I introduced the answer by stating there was no guidance on air gaps from OSHA or in the consensus standards; I was wrong. The 2017 revision of the NESC has a new rule that agrees with what I told readers, but it also refers to a new Table 444-1, “Minimum Clearances for Open Air Gaps.” In previous editions, Table 444-1 was a MAD table, but that information has been moved elsewhere in the NESC as part of a reorganization of topics. The rule states that air gaps must be made by rated insulators, cut jumpers or cut gaps that meet the Table 444-1 clearances. In the table, the air gap for 8 kV is 5 inches, which is about two-and-a-half times the MAID for that voltage.

About the Author: After 25 years as a transmission-distribution lineman and foreman, Jim Vaughn, CUSP, has devoted the last 22 years to safety and training. A noted author, trainer and lecturer, he is a senior consultant for the Institute for Safety in Powerline Construction. He can be reached at

Train the Trainer 101

Jim Vaughn, CUSP

After 25 years as a transmission-distribution lineman and foreman, Jim Vaughn, CUSP, has devoted the last 24 years to safety and training. A noted author, trainer and lecturer, he is a senior consultant for the Institute for Safety in Powerline Construction. He can be reached at