Designing Class 1 Hazardous Lighting Fixtures

- May 07, 2019-

Designing Class I hazardous lighting requires consideration of several aspects of industrial lights and fixtures. The materials that are used in the bulbs and housings is the first aspect. Those materials must be durable and able to withstand shocks, vibrations, and other environmental stresses that are common in industrial locations. Materials should be corrosion-resistant to prevent any material breakdowns that might create a greater risk of flammable vapors coming into contact with interior parts.

The next aspect for consideration is whether an industrial lighting fixture operates at a higher physical temperature. LED lighting fixtures typically do not get very hot to the touch and, accordingly, are ideal for Class I hazardous locations. 

Light housings and fixtures for Class I hazardous locations do not necessarily need to be fully sealed against flammable vapors, but at a minimum they should incorporate a baffled pathway between any potential ignition sources and those vapors. Even with a baffled pathway, many Class I hazardous lighting fixtures include thicker optics and lenses that act as a barrier between vapors and the internal parts of the bulbs and fixtures.

Mounting systems for Class I hazardous lighting  must also adhere to these design guidelines. More traditional industrial lighting might be mounted on tall poles or light standards to remove the light source from the immediate vicinity of any flammable vapors. That mounting complies with the need to separate a light source from a flammable vapor source, but it might also remove the light from the immediate vicinity of a work area and create shadows and dark spots that can impede worker safety and productivity. LED Class I hazardous lighting overcomes this limitation with custom optics that spread beam patterns more uniformly to avoid shadows and dark spots in a work area.  

Lastly, Class I hazardous lighting fixtures need to be designed to prevent the type of explosive failures that are typical of more traditional types of industrial lighting. A high or low pressure sodium bulb, for example, that is damaged by vibrations or impacts in a work area might develop a flaw that gets worse over time. That flaw can ultimately cause a sodium bulb to shatter. In the presence of flammable vapors, that shattering can lead to greater conflagrations that cover larger areas. LED industrial lighting is not prone to this type of explosive failure and, accordingly, that LED lighting is better suited to a Class I environment.