The Impact of Arc Flash Events on Photocontrol Longevity in LED Lighting

Lighting LED Control

The adoption of LED lighting continues at a rapid pace.Although the extended life of LEDs is beneficial, it also presents a compatibility challenge with older technology controls, especially with outdoor photocontrols. This rapid change to LED fixtures andluminaires can leave contractors, designers and distributors facing questions they cannot answer.

LED and other new lightingtechnologies exclusively useelectronic drivers and ballasts for operation. Their designshave different electrical start-up characteristics than older,magnetic models. In the case of photocontrols, matching theextended lifespan of LED fixtures requires a more complexcontrol unit for a reliable, turn-on/off.

Design considerations for electronic ballasts

A more complex control unit is required because some electronic ballasts produce inrush currents at turn-on that can cause premature relay contact failures. Intermatic has completed simulations in our UL-certified laboratory and has videotaped the phenomena of this spike of energy. This energy spike can and has caused control failures in the field.These inrush currents can be much higher than thoseexperienced with traditional tungsten or magnetic ballastloads because many electronic ballasts employ large energystorage capacitors. Such capacitors can charge up to 400Vfor a 277 V line voltage, and will briefly draw high currentfrom the line to achieve this voltage.

As mentioned above, these typically short inrush currentscan climb as high as 100-times the nominal operating levels.(See table below for typical inrush value comparisons.)

LED Control Table

An overlooked source of photocontrol failure

Inrush currents have not always been recognized as a source of failure for controls. Some contractors may mistakenly believe that a switch has failed because it’s a“bad” switch or a power surge has occurred. Jay Hoch, Lighting Specialist for Wyandotte Electric Supply, Wyandotte, Michigan, noticed photocontrol failures on a large, exterior LED lighting project in Detroit. “We had multiple fixtures on one circuit fail, but not all of the fixtures failed. That didn’t make any sense. If one failed, they all should.” Hoch was looking for an explanation and wondering how best to advise the contractor coming to him.Information on inrush currents supplied by Intermatic made sense of the performance of the controls that Hoch andthe contractor had noticed. After reviewing the information,Hoch realized that in rush currents were adversely impacting the controls. “The failure wasn’t in the circuit,” Hoch says.“Intermatic’s research solidified the fact that the in rushcurrent affects photo cells.”

Variances in inrush current

The inrush current magnitude and duration depends upon the value of the capacitance (measured inμF), along with circuit and power distribution network impedances.This current may weld relay contacts and other switching devices or possibly fuse semiconductors. Overall, these high-current transients can negatively impact the lifespan of traditional photo controls,negating the reduced maintenance cost associated with LED luminaires.

Therefore, the actual performance of electronic ballasts can’t be determined by a straight watt-to-watt comparison of incandescent bulbs to LED bulbs. At first glance, it may make sense to assume that ten 15 W LED bulbs could be substituted for a single 100 W incandescent bulb. However,an inrush current in the LEDs can negatively impact the control, causing failures over time.

If contractors don’t look at the specs for the controls, they may believe when a switch failsit’s a bad switch. However,providing proper control specifications would enable contractors to avoid failures that are caused by very highinrush currents.

New electronic ballast designs can provide low or zero in rush currents, but they are more costly to implement and have not been universally adopted by lighting manufacturers in the marketplace. This created a challenge for control suppliers. Hearing questions from distributors and contractors, Intermatic chose to design electronic photo controls for worst case in rush currents, as characterized bythe National Electrical Manufacturers Association (NEMA)’s survey of electronic ballast technologies.

Read the Rest of the Series:
The Impact of Arc Flash Events on Photocontrol Longevity in LED Lighting – Part 2
The Impact of Arc Flash Events on Photocontrol Longevity in LED Lighting – Part 3


Source: Intermatic Incorporated, 7777 Winn Road, Spring Grove, IL 60081; 815-675-2321; www.intermatic.com/zerocross. Intermatic’s new line of electronic photocontrols for LED applications successfully utilizes zero crossing techniques to suppress inrush current impact and deliver on the extended lifespan of LED luminaires. As a result, Intermatic offers costeffective, 8 to 12 year warrantied electronic photocontrols, while providing large inrush current carrying capacities. Lab testing shows the visible reduction of inrush current, which Intermatic has captured on video.

 

Related Articles


Latest Articles


Changing Scene

  • ABB Among TIME’s World’s Most Sustainable Companies

    ABB Among TIME’s World’s Most Sustainable Companies

    June 30, 2025 ABB has been ranked 14th in TIME’s “World’s Most Sustainable Companies 2025” and third in Switzerland across all industries. TIME and Statista assessed over 5,000 of the world’s largest and most influential companies, considering factors such as revenue, market capitalization, and public prominence. The top 500 companies from 35 countries and 21 industries were… Read More…

  • New Partnership to Deliver 1,000 Affordable Housing Units Across Quebec

    New Partnership to Deliver 1,000 Affordable Housing Units Across Quebec

    June 25, 2025 The governments of Canada and Quebec, together with Desjardins, have announced the construction of 1,000 new affordable housing units over the next three years. These housing units will be created as part of the Desjardins Affordable Housing Initiative, a partnership launched in 2022 that will now enable the delivery of over 3,000 affordable housing units… Read More…

  • CIB Closes $50M Loan with Dream Industrial REIT to Fund Large-Scale Commercial Building Upgrades

    CIB Closes $50M Loan with Dream Industrial REIT to Fund Large-Scale Commercial Building Upgrades

    June 30, 2025 The Canada Infrastructure Bank (CIB) and Dream Industrial Real Estate Investment Trust have finalized a $50 million loan to fund commercial property retrofits related to energy efficiency savings and emissions reductions at 34 warehouses in Alberta, Ontario and Quebec. With buildings currently accounting for 18% of Canada’s total emissions, investments from the… Read More…

  • Province, BC Hydro Launch Pilot Program to Cut Energy Costs, Support Housing Density

    Province, BC Hydro Launch Pilot Program to Cut Energy Costs, Support Housing Density

    June 25, 2025 In a Canadian first, the Province and BC Hydro have launched a pioneering pilot project in Vancouver that has the potential to set new standards for supporting growing housing priorities and densification in Canada. Designed to support the transition from single-family homes to multi-unit residences, the initiative is exploring how full electrification –… Read More…