DOTPLUG Breakaway Roadway wiring system aashto compliant

DOT•PLUG Breakaway Wiring System for Roadway Lighting Systems
A Safer & More Economical Lighting System

AASHTO Breakaway Wiring Requirements
Although AASHTO had set standards for breakaway (frangible) poles and foundations decades earlier, it wasn't until the 1990's that highway engineers, FHWA, and AASHTO recognized a hazard with the current wiring methods of the time. Those conventional wiring methods, unfortuately still used in the majority of lighting systems today, were identified to pose a potential deadly threat by the electric circuits that are exposed after impact by an errant vehicle. In addition to the electrical hazard the conventional wiring methods posed to motorist and emergency responders after a knock down, it was agreed that the pole wiring system must also be capable of properly separating. One reason is that the tensile strength and wire size of conventional systems directly affects the trajectory of the falling pole. Another reason is that improper separation of the electrical cabling can result in bare conductors that are still energized, posing an electrical and possible fire hazard at the accident site.

In 1996 McGraw/Hill published the first edition of the "Highway Engineering Handbook" introduced a new breakaway wiring methods/products that were being pioneered by MG Squared for the Alabama DOT at the time. Following this publication, the Federal Highway Administration (aka FHWA, US DOT) issued their own publication and guidelines - No. FHWA-HI-97-026: which duplicated the standards and designs based upon the MG Squared breakaway system set in the Highway Engineer Handbook.

In 1998 AASHTO addressed their concerns in regards to the electrical wiring inside breakaway (frangible) roadway lighting poles and issued an Interim to the Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals stating:

1.1.3 GENERAL FEATURES OF DESIGN 7
(9) when breakaway or frangible supports house electrical components, efforts should
be made to effectively reduce fire and electrical hazards should the structure be
knocked down by an errant vehicle or from some other cause. Upon knockdown, the
structure should electrically disconnect at the foundation, leaving no more than four
inches (0.10 m) of wires, cables, or connectors protruding from the electrical conduit.
All fusing for electrical fixtures should be located below grade. Performance
specifications for breakaway wiring devices should include certification from a
recognized independent laboratory that the breakaway connectors are crushproof,
flame retardant and submersible.

MG Squared's pioneering breakaway cable system had become the sole standard for a true AASHTO compliant system. Referred to in these early publications as a "Modular Cable System", "Modular Pole Cable Distribution System" (MCDS), "Pole Cable Distribution System" (PCDS, MG Squared decided to name their breakaway cable system the DOTPLUG breakaway cable system and is marketed under this name today.

Soon after 1998 AASHTO interim, some state DOT engineers were aggressive to meet these new safety standards while many have ignored and not enforced the breakaway wiring requirements. By the new millennium, research and studies revealed more and more documented cases of motorists who survived the impact with a luminaire pole, only to be subsequently killed from the resulting explosion, fire, or electrocuted from exposed conductors on, near or under a vehicle. The explosion and fire are usually caused when the fuel tank ruptures, the vehicle having been caught on an improperly constructed foundation, and the electrical system sparks repeatedly until the fuel explodes. In other incidences, medical personnel have been delayed from attending to victims because of the risk of electrical shock from exposed conductors near or under a vehicle (McGraw/Hills "Highway Engineering Handbook, 2 ed.").

In 2001 AASHTO updated their standard specifications once again for structural supports to read as:

12.5.3 Additional Requirements
Efforts shall be made in all breakaway supports housing electrical Components to effectively reduce fire and electrical hazards posed after structure impact by an errant vehicle. Upon knockdown, the support/ structure shall electrically disconnect as close to the concrete foundation (pole base) as possible.

The MG Squared DOTPLUG breakaway cable system is still today the leading system that meets current AASHTO standards and avoids the electrical and fire hazards of the conventional wiring method. Avoiding these hazards also greatly reduces the liability of the DOT, Utility Companies, design engineers, and others in relation to the electrical wiring system. Another benefit from the use of this type system is the reduction of maintenance/repair cost and time. Further advances like the incorporation of a "ground fault circuit interrupter" (GFCI/ELCI) into the wiring systems is helping avoid fatal and costly accidents resulting from worn or poorly maintained Municipal lighting systems. It is essential that as a DOT, Municipality, Utility Company or as a electrical engineer; that they be educated to avoid these hazards and to abide by all current AASHTO and/or Electrical Standards.