Neon Signs

Neon is a term that is used to describe a lighting system called electric-discharge lighting. Neon is one of the five types of gasses used in electric-discharge lighting; the other four are argon, krypton, helium, and xenon. Electric-discharge lighting works by passing an electric charge through a gas. The voltage required to perform this task is quite high compared to the voltage levels in a typical residence which are either 120 volts of alternating-current (VAC) or 240 VAC, while neon can utilize voltages up to 15,000 VAC.

The concepts behind neon signs were discovered in 1675 by a French astronomer named Jean Picard. Picard first observed a faint glow in a mercury barometer tube. At the time of this discovery, the properties of electricity were not understood, and it took another 200 years to identify that the source of the glow was static electricity. The first modern neon sign was created by a Frenchman named George Claude in 1910. The first neon sign in America was brought here by Earle C. Anthony who used the signs to advertise at his Packard automobile dealership.

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The Underwriters Laboratory (UL) and the National Electric Code (NEC) are two sources for rules and regulations pertaining to the manufacture and installation of neon signs. The NEC rules are considered the basics for a safe installation. However, there are times when they are not followed, and the installation errors are not found by the inspector. Some of these issues may result in damage to equipment such as neon sign transformers, personal injury, or fire.

While there are several aspects of neon signs installations, we will focus on two rules. The first is proper bonding and grounding of the metal equipment used on the high voltage, (secondary) side of the neon transformer. Recall that neon signs can utilize voltages up to 15,000 VAC. Without proper bonding and grounding, fault currents on the neon sign secondary may seek alternate paths back to the source (neon sign transformer). At 15,000 VAC this path may be through combustible material; especially when combined with moisture during a rain, or damp air. The second aspect of neon sign installation is the NEC requirement that listed and labeled equipment be installed in conformance with that listing, unless otherwise approved by special permission. This is an important point in regard to neon signs. For instance, electrode boots are used to cover the connection between GTO cable and neon tube electrodes. The appropriate boot should be used for the anticipated exposure to water. For example, an installer must use electrode boots that are rated for wet conditions if the sign is located outdoors and will be subject to water saturation, i.e. rain. If electrode boots listed for damp or dry locations are used instead, moisture may be able to contact the energized conductors. If this is combined with a sign that is not properly bonded and grounded, the result may be a fault current seeking other paths back to the transformer–either through combustible materials, which may lead to fire, or through metal parts, which may lead to personal injury.

If a neon sign is suspected source of ignition or injury in a loss, some of the factors that need to be addressed are:

• Adherence to codes and standards
  • Neat and workmanlike installation
  • Proper bonding and grounding
  • Listed and labeled equipment
  • Equipment installed and used per that listing
  • Protection from physical damage
• Were persons involved qualified?
• Was the installation inspected?
• Was the installation maintained?

Neon signs installations can be safe and last for many years if installed correctly and maintained properly.