German light manufacturer and Siemens subsidiary Osram said the lighting units placed over 975 LED lamps would reduce annual power consumption at the 63sq.km mine from 427,050 kilowatt hours to 170,820kWh.

The operation’s annual savings have been projected at more than $35,300.

Lighting professionals regard underground coal mines are one of the most challenging environments – with low reflectivity, low contrast, high temperatures and a high-corrosive environment. Osram said using LEDs in place of incandescent lamps would help.

Osram applied its versatile Oslon SSL series to Xishan Duerping and said the 20W LED lamps serviced the mine through two different designs.

Round lights are used for general purposes underground, while square ones used are for long distance lighting inside tunnels. Because of the low reflectivity in coal mines, the output of light sources needs to be much higher.

“We have chosen Osram’s Oslon SSL LEDs for their high reliability and efficiency,” Shenzhen General Technology chairman Zhong-hua Li said.

“More importantly, the light output of these LEDs is high enough for good designs. The average luminance is 82Lx, compared to 45Lx of the previous incandescent lamps. With the use of advance optics, we are able to reduce glare to a minimum in this low contrast environment.”

Osram said the lights also conformed to requirements for coal mine safety certification, explosion-proof certification, salt spray, waterproof testing, impact test and the 1000-hour burning test.

Kai-chong Cheng is the senior marketing director of Osram Opto Semiconductors Asia.

“The use of LEDs in coal mine lighting is definitely taking off,” he said.

“As LEDs do not use any glass envelope and cannot break, we hope the use of these LED lamps will reduce hazards for the people who work underground.”

According to a study by the US National Institute for Occupational Safety and Health, the greatest percentage of accidents (53%) happened during the maintenance and repair work of light bulbs or light fixtures.