National Electrical Code (NEC)

Through the efforts of the Electrical Subcommittee, ISA actively influences the shape and content of the National Electrical Code (NEC) and, in particular, NEC Article 600. During the 2011 and 2014 Code cycles, ISA has been instrumental in updating NEC requirements to reflect electrical safety needs and evolving technologies in the sign industry. In November 2011, ISA submitted proposals for the 2014 NEC and it's anticipated that this edition of the Code also will reflect the conscientious efforts of ISA members.

Typically, a significant amount of time passes between publication of new versions of the NEC and their adoption by Local Authorities Having Jurisdiction (AHJs) responsible for enforcing the Code. Thus, while some jurisdictions might be enforcing more recent editions of the Code, others might still enforce earlier Codes. To review the NEC edition currently being enforced in specific jurisdictions, consult the NEC Adoption by State.

To ensure that sign industry personnel are familiar with the most recent NEC changes, ISA has created Guidelines for Application of 2011 NEC Changes in Electric Sign Requirements, a comprehensive guide for the practical application of NEC Article 600. This new resource highlights all changes in Article 600 and provides clear explanations, visual examples and background information concerning these changes. View the guide here


Q. What is the Principal Focus of ISA's Ongoing Efforts to Affect Development of the NEC?
ISA develops proposals for the NEC on a 3-year cycle corresponding to publication of Code updates by the National Fire Protection Association (NFPA). ISA aims to bolster electric-sign safety and to ensure that NEC Article 600 and other Code sections referenced therein reflect current technology and practices in the electric-sign industry. ISA proposals also aim to clarify the NEC requirements for electric signs to facilitate proper interpretations and enforcement of the Code by local Authorities Having Jurisdiction (AHJs). In developing these proposals, ISA also seeks input from UL, the International Association of Electrical Inspectors (IAEI) and other sign associations. ISA's broad goal is to enhance electric-sign safety while facilitating acceptance of electric signs by local government authorities.

Q. How is ISA Enhancing Safety for Sign Industry Personnel?
During the current cycle for the 2014 NEC, ISA submitted a proposal to clarify the requirements under NEC 600.6 (A)(1) for the location of disconnect switches that control electric signs and outline lighting systems. This proposal has been accepted in principle by NFPA Code-making Panel 18, pending consideration of further comments. The proposal aims to eliminate the possibility that, even when a sign disconnect switch is in the "off" position, a sign body or enclosure might still contain energized conductors.

Energized supply wires sometimes enter a sign body at points located apart from the disconnect switch location (e.g. through the sign's backing) and then traverse the sign's interior to the disconnect switch. Thus, even when the disconnect switch is "off," supply wires within the sign body remain energized. Shutting off the switch, therefore, does not necessarily disconnect all of the sign's internal wiring. Thus, a technician repairing the sign assumes that the power is "off" and might be electrocuted when contacting these live conductors.

The accepted proposal for the 2014 NEC 600.6 (A)(1) states the following:

"The disconnect shall be located at the point the feeder circuit or branch circuit(s) supplying a sign or outline lighting system enters a sign body or enclosure.

(1) At Point of Entry to a Sign Enclosure: The disconnect shall be located at the point the feeder circuit or branch circuit(s) supplying a sign or outline lighting system enters a sign enclosure and shall disconnect all wiring where it enters the enclosure of the sign."

This proposed requirement is subject to the following exception: "A disconnect is not required for branch or feeder circuits passing through the sign where enclosed in a Chapter 3 listed raceway."

In recent Code cycles, ISA proposals also have clarified NEC requirements for electrical grounding and bonding to enhance safety.

Q.  Why Does ISA Support Listing of Skeleton Neon Tubing?
 The current exception in the National Electrical Code (NEC), which exempts skeleton neon tubing from listing requirements, was incorporated into the 1996 NEC, Article 600.3.  When the 1996 Code was developed, the scope of the UL 48 Standard, 14th Edition, did not include field-assembled, skeleton neon tubing. The following is the substantiation of NFPA Code-making Panel 18 for creating this exception in 1996:

"Skeleton tubing is the only form of sign or outline lighting for which a listing cannot be obtained, because it is frequently field installed.  All other forms of signs or outline lighting can be manufactured as listed products."

During the 1996 NEC Code cycle, ISA took a leadership role in rewriting and reorganizing Article 600.  As stated above, UL's position was that skeleton tubing incorporates field wiring and, therefore, was ineligible for listing. The rationale for this judgment was that the structure (e.g. a building facade) to which the skeleton tubing was attached could not be brought into a sign shop for evaluation. Thus, without any available ANSI/UL standard for skeleton tubing, a provision was made to exempt skeleton tubing from the listing requirements.

Published in September 2011, however, the 15th Edition of UL 48 incorporates skeleton tubing within the scope of the Standard, thus nullifying the basis for this exception (UL 48.1.2).

The Standards Technical Panel (STP) for UL 48 spent many years amending the Standard in piecemeal fashion to accommodate advancing technology in the sign industry. Ultimately, however, it became clear that a complete revision of UL 48 was necessary, thus leading to publication of the 15th Edition. The STP for UL 48, comprising members representing various segments of the sign industry, expressed no objections to eliminating the exception for skeleton neon tubing and the panel voted affirmatively to incorporate it into UL 48. In the 15th Edition of the Standard, the corresponding listing requirements are described in 4.4.11. As stated in UL 48, "Wiring for a skeleton neon tube sign or outline lighting is not required to be complete before it leaves the factory." Thus, when the 15th Edition of UL 48 was published, the basis of the current exception for skeleton tubing became invalid.

The current UL 48 Standard provides a path for listing of field-installed skeleton tubing by any Nationally Recognized Testing Laboratory having signs within its scope. Furthermore, listing of field-installed skeleton neon tubing has been available under UL's UZBL program since 1997 according to the UL White Book.

To support electric-sign safety and also to follow the accepted practice of harmonizing the NEC with UL Standards, therefore, ISA submitted a proposal for the 2014 NEC which supports a requirement for listing of skeleton tubing systems.  NFPA Code-making Panel 18, however, has rejected this proposal pending consideration of further comments.