Three ways to light a factory

Lux's technical editor Alan Tulla looks at three ways to approach lighting for factories

Factories have changed a lot over the past couple of decades even if the buildings have not. This means that when you come to relight a factory, there are many more factors to consider than previously. 

Most factories contain large, tall machinery and plant hence the name highbay used to light them. Traditionally, access for maintenance and relamping at height was always a problem. Most highbays used HID lamps. High pressure sodium had good lamp life, maybe 25,000 hours, but the colour rendering was pretty poor. If you wanted good colour rendering you had to use metal halide or Deluxe versions of hps but their life was only 10,000 – 15,000 hrs.

LEDs have changed all that. Their long life means that maintenance is greatly reduced. There are further savings in that in factories that work 24/7, you don’t have the enormous cost of stopping a production line simply to change a lamp. 

One aspect of industrial lighting that is often forgotten is that the ambient air temperature around a highbay may be considerably higher than at a “normal” ceiling height. It’s worthwhile checking the temperature at the height the luminaires will be mounted. Both the JCC luminaires used here can operate at 60C; much more than some of their competitors. 

In industrial areas, BS EN 12464 Part 1 allows you to use a light source with a lower CRI than usual, depending on the use of the space. Usually CRI 70 instead of CRI 80.  Check what you require and use the advice given in BS EN 12464 or the Code for Lighting.  Both luminaires used here are CRI 80 and have a CCT of 5,700K. 

All the options here produce at least 300 lux Eh on the conveyor belt. The vertical illuminance changes with each option. 

Our factory measures 25m x 18m. The roof is pitched from 8m to 10m.

This uses the 180W Toughbay™ circular highbay unit. It is similar in appearance to a conventional HID highbay but much shallower. It is intended to be a direct replacement for a 250W metal halide luminaire thus giving about 30% energy saving and much longer life.
Sometimes you need light from floor to ceiling but for this particular application, we have fitted a reflector which narrows the beam from the standard 110° to just 60°. You can see from the image that it is the lower half of the factory which is illuminated. 

An advantage of the complete range of Toughbay™ luminaires is that they are all IP65 and fitted with polycarbonate lenses/diffusers.

Tech spec
  • Luminaires180W Toughbay™ Circular
  • Optical control
  • Polycarbonate diffuser plus reflector
  • Arrangement
  • 3 x 4
  • Average illuminance on conveyor belt405 lx Eh.
  • Electrical load
  • 5.7 W/m2
  • Pros
  • Concentrates the light in a narrow beam

The Toughbay™ Linear is an LED luminaire with the appearance of a fluorescent unit. There are three versions, 75W, 150W and the one we have used is 210W emitting 19,000 lm. It is intended as a replacement for 4 x 80W T5 fluorescent luminaires. 

This linear version has a similar lumen output, but much wider beam, than the circular reflector unit in Option A.  The result is that the factory walls and machinery are illuminated almost to the roof. You can see that the high level tank area and office is very well illuminated. Like the circular Toughbay™, it is IP65 and has a polycarbonate diffuser. 

Another really useful application for this luminaire is in cold stores and freezers where it can operate down to -30C.

Tech spec
  • Luminaires
  • 210W Toughbay™ Linear
  • Optical control
  • Polycarbonate diffuser
  • Arrangement
  • 3 x 4
  • Average illuminance on conveyor belt365 lx Eh
  • Electrical load6.3 W/m2 
  • ProsUseful where you want illumination high up

One of the best ways to save energy in a factory is by using controls. This option uses the same luminaires as Option A but fitted with a Leviton multi-function microwave sensor. The first function is a simple occupancy sensor for areas which are infrequently used. This simply switches On/off.
However, for busier areas, the sensor uses step dimming. When no movement is detected, the sensor dims the luminaires to 10% - 50% of full output. This retains a low level of illumination for safe movement. 

The sensor can be used up to heights of 15m, much taller than the factory shown. It has a 16m detection range which can be adjusted up to 50% by using Dip switches. 

Here you can see that the foreground is unoccupied and the lighting has been dimmed to just 10% of full output. The furthest work area and exit doors are illuminated at full output.

Tech spec
  • Luminaires
  • 180W Toughbay™ Circular
  • Optical control
  • Polycarbonate diffuser plus reflector
  • Arrangement
  • 3 x 4
  • Average illuminance on conveyor belt405 lx Eh.
  • Electrical load3.4 W/m2  but  half area is illuminated to 10% Emax
  • ProsEnergy saving