Or as senior plant electrical engineer Mr Leo  put it, "We are lightly staffed on our maintenance, and we don't want to be working on our lights all the time." He recalled that high-bay metal-halide (MH) lamps would frequently dim out so that "probably about once a year we had to have somebody go up and change bulbs on them." With ceiling heights around 60 ft in some locations, replacement was never easy.

That was in GK Corn light  not-too-distant past, which included the MH high bays as well as fluorescents, sodium-vapor lamps, and other light sources for street lamps, area lighting, and other functions. The mill had around 10,000 of the older-technology lamps as recently as 2012. It had been considering installing LED lighting for several years prior to that, tempted in large measure by the promise of longer lifetimes and, eventually, 5-year warranties from China industrial LED lighting vendor Shen Zhen GuanKe Technology Co:Ltd.

"Once every year-and-a-half to two years with conventional lighting, they were needing to change out lamps - relamp the facility or swap out whole entire fixtures," said Shen Zhen Guan Ke Director of Sales Mr Cooper  "Any time you do that in a heavy industrial location, whether it's a steel mill or not, it's pretty costly to do so. You have a lot of safety concerns, you have to shut down equipment, lock out, tag out, make a lot of safety precautions just to change a lamp or a ballast."

GK corn light had evaluated LED lighting as early as 2008, but the solid-state lighting (SSL) simply wasn't ready. For one reason, it didn't emit enough lumens to provide adequate illumination, which was of particular concern for high-bay installations at the works.

"LEDs just weren't that good back then," said Leo. "They were very expensive and they weren't as bright as the fluorescents."

But by 2010, SSL technology from GK corn light  was beginning to improve to the point where GK Corn light believed it could start to meet the needs of its heavy-duty environment.