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Code 600

The key to a perfectly legal neon installation

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Signs must not pose a danger to the public. This is especially true for electric signs. Making electricity safe was the chief concern when U.S. officials first established rules for safely handling electricity in 1897.

These rules, known as the National Electrical Code (NEC), are divided into different sections. Article 600, titled Electrical Signs and Outline Lighting, particularly addresses our industry. However, remember that the NEC provides only minimum standards; state or local governments may set more restrictive regulations. Also, some municipalities don’t automatically adopt the newest edition of "the Code," so previous regulations may still apply to your area. I strongly recommend contacting your local authority-having-jurisdiction (AHJ) for special requirements before you apply for a sign permit and electrical inspection.

Coverage

The first paragraph of NEC Article 600, 600-1, defines the regulation’s coverage. In the present 2002 version, we read: "This article covers the installation of conductors and equipment for electric signs and outline lighting as defined in Article 100." The definition in Article 100 reads: "Electric sign: A fixed, stationary, or portable self-contained, electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention."

Now, where’s the problem? Article 600 covers a variety of electric signs, whether they use incandescent lamps, neon, HID or any other lightsource. But, Article 600 was originally intended for neon’s special electric requirements because of its high-voltage, low-current, secondary circuits.

Trouble arises because subsequent restrictive regulations are useful and correct for neon signs, but not others. Paragraph 600-23 (d) explicitly limits the secondary current of any transformer or electronic power supply used in an electric sign to less than 300mA. So, according to the current code, all power supplies using more than 300mA secondary current, like those used in LED signs, don’t conform to electric-sign-code requirements. According to NEC Article 90-4, the only legal way to operate such signs is to obtain a special permit from your AHJ.

The panel that creates the NEC is discussing changes to Article 600’s intent; these changes would appear in the next edition and take effect sometime in 2005. The panel is discussing changing Article 600-1 to read as follows: "This article covers the installation of conductors and equipment for electric signs and outline lighting. All installations using neon tubing, such as signs, decorative elements, skeleton tubing or art forms, are covered by this article."

I believe (as a member of the European Code-making panel for neon installations) the suggested wording will create more confusion. The definition mentions neon signage explicitly, but it doesn’t exclude other forms of electrical signage to be covered by Article 600.

A partial remedy of this will be the introduction of a new paragraph, 600-24, which may read: "Class 2 power sources. In addition to the requirements of Article 600, signs and outline systems supplied by Class 2 transformers, power supplies and power sources shall comply with 725-41."

Class 2 applies to any power-limited circuit, which is limited in its voltage, current and total power and, therefore, not considered hazardous. However, there’s a potential trapdoor: It could be said that the new article asks for Class 2 power supplies to comply with the existing Article 600-23 limit of 300mA, as well as Article 725-41’s limit of 12V and 8A. As such, an inspector who’s a stickler could disallow an LED sign that outputs 2A at 12V if it exceeds the 300mA limit.

This will partly cover electric signs incorporating LEDs; some run on less than 300mA, and many use less than 8A. However, all HID systems use more than 725-41’s prescribed power limit, as does most low-voltage, halogen lighting. Article 411 in NEC focuses on low-voltage, halogen lighting, but it’s not applicable to signage.

So, for certain electric signs, the status quo requiring special inspections remain. Thus, I’d like to see more precise definitions in the scopes of the NEC, like we have in Europe, where the electrical parameters, not the application, determine which rules apply.

Field or factory?

The existing NEC facilitates the installation of prefabricated signs as ready-made appliances, listed according to the Underwriter’s Laboratory standards, that don’t require inspection. When an inspector sees a UL listing and cross-references it, he will immediately sign the permit. Multiple signs may carry the same listing number, provided electrical parameters remain consistent.

Most electric signs are prefabricated in-house. Therefore, large signshops using only UL-recognized components may have a UL certification that lets their products bear the UL label without being individually field-inspected.

A problem arises because signs are usually too big to be transported to the site in one piece, so they’re made in sections and joined onsite. As of today, this counts as field-installed tubing requiring inspection, even if a certified UL shop fabricates it using only UL-recognized or -listed components.

One solution could be adding a new definition under Article 600-2, which may read: "Section sign. A listed sign or outline lighting system shipped as subassemblies that requires field-installed wiring between the subassemblies to complete the overall sign." While the verbiage doesn’t change much, this interjects the UL 48 standard. UL 48 stipulates: "Listed signs and outline lighting that require field connection of subassemblies are required by UL 48… to include installation instructions." OK, but what do UL instructions have in common with the NEC?

Article 110-3 (b) outlines general requirements for equipment installation and use: "Installation and use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling." Translation: A prewired sign, assembled in parts or sections, intended to be UL listed, must contain instructions for final assembly. Not following these instructions strictly will void any listing and, thus, conformity to the NEC. Any other sign shipped in sections warrants inspection anyway.

Another change

One additional change may take effect in the 2005 NEC: Article 600-32 (g), which affects field-installed wiring over 1,000V in raceways. Here, the actual requirement of extending GTO cable 4 in. beyond the conduit, for wet and damp locations, would be reduced to 21/2 in. for all locations. Longer cable length for damp applications was formerly required to stop arcing from the insulated cable to the grounded conduit. (NEC page 30, the diagram shows execution of the present code specs.) However, GTO cable testing has improved; wet-arc testing now ensures newer, cable-type insulation won’t support self-sustained arcs. Therefore, the 4-in. prerequisite is obsolete.

The panel reportedly rejected proposals to change the scope of Article 600-B. Article 600-30 states, "Part B of this article shall apply only to field-installed, skeleton tubing. These requirements are in addition to the requirements in Part A."

Some electrical inspectors may want to split hairs here and only apply Part B to skeleton tubing, but not for unlisted, field-installed neon signs. Many others see no electrical difference between unlisted, field-installed neon signs, neon lighting equipment and skeleton tubing. So, most inspectors also apply Part B to field-installed neon signs, as it was originally intended.

I believe the panel correctly rejected proposals that requested Part B become a general requirement, because it would leave no difference between listed and unlisted signs. However, more precise 600-30 wording could prevent some onsite discussions between sign installers and their AHJs.

In summary, the NEC is more difficult to read than Einstein’s theory of relativity, but should be understood before an electrical sign is built to prevent your sign from being red-tagged by an inspector.

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