You can either just rely on your sense of sight, or use a lux meter to measure the lighting levels. With our inexpensive delamping kit we supply a lux meter and delamping guide, which advises what the minimum illumination levels should be for a wide range of building types and room uses. If the lighting levels are inadequate afterwards, upgrade to a brighter fluorescent tube, such as a "tri-phosphor" tube or the even brighter "quad-phosphor" tube. The use of a lux meter is the preferred method, because you can then demonstrate compliance with lighting standards and Occupational Health and Safety requirements
By using a reflector it was possible to remove one tube from this fitting - and halve its power use.