National Electrical Safety Code

Generally speaking, the standard of care for campus power system safety is set by both the NEC and the NESC. There are gaps, however (or, at best "gray areas") -- the result of two technical cultures: utility power culture and building fire safety culture. There is also tradition. Local system conditions and local adaptation of regulations vary. Where there is a gap; the more rigorous requirement should govern safety of the public and workers.


National Electrical Safety Code

March 3, 2023

Image: Cynthia Griggs | Academy of Art University


February 24, 2023


The new code goes into effect 1 February 2023, but is now available for access on IEEE Xplore! Produced exclusively by IEEE, the National Electrical Safety Code (NESC) specifies best practices for the safety of electric supply and communication utility systems at both public and private utilities.  The bibliography is expanding rapidly:

NESC 2023: Introduction to the National Electrical Safety Code

NESC 2023: Rule Changes

NESC 2023Safety Rules for Installation and Maintenance of Overhead Electric Supply

NESC 2023Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines

NESC 2023: Rules for Installation and Maintenance of Electric Supply Stations

IEEE Digital Library

October 31, 2022

The IEEE NESC technical committee has released a “fast track” review of proposed changes to fault-managed power system best practice:

CP5605 Provides a definition of new Fault Managed Power System (FMPS) circuits used for the powering of
communications equipment clearly defines what constitutes a FMPS circuit for the purposes of application of the NESC
Rules of 224 and 344

CP5606 Provides new definitions of Communication Lines to help ensure that Fault Managed Power Systems (FMPS)
circuits used for the exclusive powering of communications equipment are clearly identified as communications lines
and makes an explicit connection to Rule 224B where the applicable rules for such powering circuits are found.

CP5607 The addition of this exception permits cables containing Fault Managed Power System (FMPS) circuits used for
the exclusive powering of communications equipment to be installed without a shield.

CP5608 The addition of this exception permits cables containing Fault Managed Power System (FMPS) circuits used for
the exclusive powering of communications equipment to be installed without a shield.

We refer them to the IEEE Education & Healthcare Facilities Committee for further action, if any.


August 5, 2022

We collaborate closely with the IEEE Education & Healthcare Facilities Committee (IEEE E&H) to negotiate the standard of care for power security on the #SmartCampus  since many campus power systems are larger than publicly regulated utilities.  Even when they are smaller, the guidance in building the premise wiring system — whether the premise is within a building, outside the building (in which the entire geography of the campus footprint is the premise), is inspired by IEEE Standards Association administrated technical committees.

Northeast Community College | Norfolk, Nebraska

Today we begin a list of noteworthy changes to be understood in the next few Power colloquia.  See our CALENDAR for the next online meeting.

  1. New rules 190 through 195 cover photovoltaic generating stations.  Rule 116c adds an exception for short lengths of insulated power cables and short-circuit protection if the situation involves fewer than 1,000 volts.
  2. Rule 320B has been revised to clarify separations that apply to communications and supply in different conduit systems.
  3. Table 410-4 is based on the latest arc flash testing on live-front transformers.
  4. Rule 092A adds an exception allowing protection, control, and safety battery systems to not be grounded.
  5. Rules 234 B1, C1, D1 were revised to better present vertical and horizontal wind clearances, and to coordinate requirements with the new Table 234-7.
  6. Rule 120A was revised to provide correction factors for clearances on higher elevations.
  7. Table 253-1 has been revised to reduce the load factor for fiber-reinforced polymer components under wire tension—including dead ends—for Grade C construction.
  8. Rule 410A now requires a specific radio-frequency safety program for employees who might be exposed.
  9. In the Clearances section, as well as in the specification of the Grade of Construction in Table 242-1, the Code further clarifies the use of non-hazardous fiber optic cables as telecom providers continue to expand their networks.
  10. Revisions in the Strength & Loading sections include modified Rule 250C, which addresses extreme wind loading for overhead lines. Two wind maps are now provided instead of the previous single one. A map for Grade B, the highest grade of construction, with a Mean Recurrence Interval (MRI) of 100 years (corresponding to a one percent annual probability of occurrence) is provided in place of the previous 50–90-year MRI map. For Grade C construction, a separate 50-year MRI (two percent annual probability of occurrence) map is now provided. In the previous Code, a factor was applied to the 50–90-year MRI map for application to Grade C.
  11. Changes were also made to the method of determining the corresponding wind loads, consistent with the latest engineering practices as an example of a Code revision focused on public safety, the ground end of all anchor guys adjacent to regularly traveled pedestrian thoroughfares, such as sidewalks, and similar places where people can be found must include a substantial and conspicuous marker to help prevent accidents. The previous Code did not require the marking of every such anchor guy.
  12. Significant revisions were made in Section 14 covering batteries. Previous editions of the code were based on lead-acid technology and batteries only used for backup power. The 2023 Code incorporates the new battery technologies and addresses energy storage and backup power.
  13. A new Section 19 of the code covers photovoltaic generating stations, with sections addressing general codes, location, grounding configurations, vegetation management, DC overcurrent protection, and DC conductors. These new rules accommodate large-scale solar power projects.
  14. In the Clearances section, all rules for wireless antenna structures have been consolidated in the equipment section (Rule 238 and 239), which makes the Code more user-friendly.
  15. A new subcommittee was created focusing on generating stations, with the original subcommittee continuing to address substations.
  16. A working group is investigating Fault Managed Power Systems (FMPS) cables as the technology may be used for 5G networks. The team is looking at possible impacts, including clearances and work rules.


February 18, 2021


Several proposals recommending improvements to the 2017 National Electrical Safety Code (NESC) were submitted to the IEEE subcommittees drafting the 2022 revision of the NESC.   Some of the proposals deal with coordination with the National Electrical Code — which is now in its 2023 revision cycle.  Keep in mind that that NESC is revised every 5 years at the moment; the NEC is revised every 3 years.

The original University of Michigan standards advocacy enterprise has been active in writing the NESC since the 2012 edition and set up a workspace for use by electrical professionals in the education industry.   We will be using this workspace as the 2022 NESC continues along its developmental path:

IEEE 2022 NESC Workspace

The revision schedule — also revised in response to the circumstances of the pandemic — is linked below::

NESC 2023 Edition Revision Schedule*


The NESC is a standing item on the 4-times monthly teleconferences of the IEEE Education & Healthcare Facilities committee.  The next online meeting is shown on the top menu of the IEEE E&H website:

IEEE E&H Committee

We have a copy of the first draft of the 2023 NESC and welcome anyone to join us for an online examination during any of Power & ICT teleconferences.  See our CALENDAR for the next online meeting.

Business unit leaders, facility managers and electrical engineers working in the education facilities industry may be interested in the campus power system reliability database.   Forced outages on large research campuses, for example, can have enterprise interruption cost of $100,000 to $1,000,000 per minute.    The campus power system forced outage database discriminates between forced outages attributed to public utility interruptions and forced outages attributed to the university-owned power system.   The E&H committee will convey some of the discipline applied by the IEEE 1366 technical committee into its study of campus power systems and, ultimately, setting a benchmark for the standard of care for large university power systems.


* The IEEE changed the nominal date of the next edition; likely owed to pandemic-related slowdown typical for most standards developing organizations.

Issue: [16-67]

Contact: Mike Anthony, Robert G. Arno, Lorne Clark, Nehad El-Sharif, Jim Harvey, Kane Howard, Joe Weber, Guiseppe Parise, Jim Murphy

Category: Electrical, Energy Conservation & Management, Occupational Safety

ARCHIVE: University of Michigan Advocacy in the NESC 2007 – 2017


P1366 – Guide for Electric Power Distribution Reliability Indices 

University Design Guidelines that reference the National Electrical Safety Code


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