Design the light, then pick the fixture
It is tempting to begin with a fixture catalog. Lighting professionals more often begin with the space and the work. The question is what people need to see, where and for how long, and the fixture follows from that. Information on lamp types and mounting is available in the companion article on choosing industrial lighting for a facility; this one deals with layout and quality of light.
Brightness depends on the task
The amount of light on a surface is measured in lux (or footcandles in some countries). Different tasks need different levels. Walkways and storage aisles usually need less than a bench where small parts are assembled or inspected. Fine detail, low contrast, fast-moving parts, and older workers all push the requirement upward.
Recognized lighting standards and recommended practices list levels for different activities, and local regulations may set minimums. A designer should use the standards that apply at the site rather than a single number from an article. The levels are measured on the work surface or at floor level, not at the fixture.
Layout and spacing
Layout determines how evenly light is spread.
- General (ambient) lighting. Fixtures laid out in a regular pattern across the ceiling provide a base level of light.
- Task lighting. Additional fixtures near a bench, machine or inspection station supply higher levels where needed, without raising the level of the whole room.
- Mounting height and spacing. Higher mounting generally spreads light more widely but may reduce the amount that reaches the work surface. A common design rule is to keep spacing between fixtures within a limit related to mounting height, and manufacturers publish spacing guidance for each optic.
- Aisles and racking. In warehouses, tall racks block light. Fixtures placed over aisles, rather than in a grid that ignores the racks, usually light vertical rack faces better, which matters for reading labels.
- Walls and ceilings. Light-colored surfaces reflect more light and make a space feel brighter.
Many designers use software to calculate and simulate a layout before installation. Simple hand calculations can give a rough estimate, but checking with a qualified lighting designer is better for large projects.
Uniformity
A space with a high average level can still be uncomfortable if some areas are dark and others bright. Large differences make the eye work harder to adapt, and shadows can hide hazards such as steps, forklifts or machine guards. Designers aim for a reasonable ratio between the brightest and dimmest areas, and use the same ideas for aisles and work zones.
Glare and shadows
Glare comes from bright sources in the field of view or from reflections off shiny surfaces such as polished metal or glossy floors. It causes fatigue and can hide detail.
- Use fixtures with optics or shielding that control the angle at which light leaves.
- Avoid placing fixtures where a worker’s line of sight meets them directly, for example low in front of a crane operator’s cab.
- Consider the reflections from screens and from machined parts.
- Be careful with flicker. Some lamp and driver combinations produce flicker or stroboscopic effects that can make rotating machinery appear to be standing still. This is a real safety issue, so a lighting designer should check it near rotating equipment.
Color quality
Color temperature affects how warm or cool the light looks, and color rendering describes how faithfully colors appear under it. Tasks like color matching, inspection of wiring or reading color-coded labels may need better color rendering than ordinary storage.
Controls, energy and maintenance
Controls such as occupancy sensors, daylight sensors and dimming can lower energy use, particularly in warehouses where aisles are empty for long periods. These ideas belong to the broader topic of industrial energy consumption. Lamps and fixtures also lose output over time and collect dust, so designers allow for this loss and plan cleaning and replacement. Access matters: fixtures hung high over racking or machinery can be hard to reach.
Safety and special areas
Emergency and exit lighting is usually required by code, and must be tested as the rules say. Hazardous areas may need fixtures rated for flammable dust or vapors; the principles are those of hazardous area equipment. Fixtures installed or serviced at height or connected to power should be handled by qualified electricians following local regulations and lockout and tagout style procedures.