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Energy Smart Transit for 2013

Posted on Thursday 3rd January 2013
Transit Lighting Report

Saving Energy is top of mind for many energy and operations managers of Transit Authorities both in the U.S. and in countries around the world. In reviewing transit opportunities in New York City, some analysts have come across what is called the “Flicker Factor”. Simply, existing fluorescent tubes that use the tombstones end brackets for the electric circuit often flicker when subway trains are moving or when the tubes in the stations flicker as an express train runs straight through to the next station. The phenomenon is attributed to the fact that the movement of the train on the tack or the air pressure created by an express train in a station creates a very slight movement of the pins at the end of the fluorescent tubes that touch the inside of the tombstone bracket.

This is a key consideration in Energy “Smart” retrofits, since managers want to both save money on electricity but also improve if possible the current lighting in any given environment. With the increasing popularity of the high efficient LED tube, buyers have options of internal and external driver led tube products. The trend is toward the new “Standard” of External Drivers, see: However, cutting the cost of electricity for lighting by 50% or more over a fluorescent tubes with an LED tube, is not great if the new LED tube also flickers. Both internal and external driver LED tubes typically use the existing tombstone brackets to run the circuit, so they are just as vulnerable to flicker as their fluorescent predecessor tubes.

An American manufacturer of LED tubes may have found a solution for transit facilities that was an unintended benefit of their external driver technology. Independence LED ( makes an LED tube with an external “independent” driver. According to Charlie Szoradi, the Independence LED Chairman and CEO, “The engineering on our independent driver was initially designed for thermal management to protect the diodes and to by-pass the tombstones so that we could offer the benefits of beam angle adjustments on each tube.”

Beyond the flicker reduction, LED tubes that do not rely on the old tombstones have the added “Smart” Energy advantage of maintenance reduction. Commercial lighting maintenance staff across the planet can testify to the fact that, as tombstones age, the plastic becomes more brittle. If a small piece of the tombstone breaks then arcing can occur and compromise the safety of the fixture. Replacing old and damaged tombstones is a requirement if the circuit runs through that bracket, but it is not necessarily a requirement for an LED tube that by-passes the charge through the bracket. Companies such as Independence LED have gone to the length to secure approval from Underwriters Laboratories (UL) for retrofit classifications that include support such as approved zip ties that are faster, cheaper, and stronger than replacement tombstones.

As the Energy Revolution progresses, saving money and going green by reducing toxic mercury from the fluorescent tubes has layers of twists and turns such as this flicker reduction in a sector like transit. Other advantage of LED tubes and advanced technology will most likely surface in other sectors as well.

LED Saving Solutions