Shops with lots of area and high ceilings (high bays) are common candidates for high-output lighting designs because large square footage combined with very high ceilings put a lot of pressure on lighting systems to provide adequate illumination, say officials at Larson Electronics (www.larsonelectronics.com), a manufacturer of industrial lighting and power distribution products.
“Fluorescent lighting does hold some advantages over HID (high intensity discharge) metal halide systems when it comes to high bay applications,” acknowledge the officials. “Cheaper lamp and fixture costs, fewer issues with end-of-life cycling and lumen deterioration and cooler operation provide tempting potential that in some cases can help fluorescent outperform in some high-bay applications.
“However, fluorescent systems have their own drawbacks,” observe the officials. These include “poor cold weather performance and lower output, requiring the installation of more fixtures, and the fact that in order to switch a facility from metal halide to fluorescent, it is necessary to perform a full system-wide changeover, including entire new fixtures, mounting hardware and, in some cases, wiring, which in turn means a slower return on initial investment that may make the switch less than cost effective.
“All of this often acts to cancel out the benefits of fluorescent systems and make them a less-than-ideal alternative to HID metal halide,” they say.
CEILING HEIGHT
According to the Illuminating Engineering Society of North America (IESNA), “high bay” refers to higher ceilings, typically 25’ and higher in height. “Low bay” indicates ceilings with heights below 25’.
Metal halide lighting is the preferred type of lighting system for high bays due to their intense output, good color quality, high efficiency and long lamp life, Larson Electronics officials explain. “Metal halide lamps represent the most powerful form of industrial and commercial lighting and are capable of covering extremely large areas with relatively few fixtures opposed to other forms of lighting.”
Although other HID systems – such as low-pressure sodium and high-pressure sodium – provide similar overall lumen out, lamp life and efficiency, their very poor light quality often “makes them a poor choice for indoor industrial or commercial operations where light quality is a critical factor in maintaining safe and productive operations.”
