Glossary

The type and rating of plastic diffusers used in luminaires, for compliance with The Building Regulations 2010 Fire Safety Approved Document B, Volume 2: Buildings other than Dwelling Houses. Only applies to recessed fittings, where the diffuser forms part of the ceiling. Diffusers are rated TP(a) or TP(b) according to their ability to restrict the […]

The ratio of working (true) power (W) to the total (apparent) power (VA), measuring efficiency in an AC power system.

The unit of surface brightness of an object, expressed in candelas/m² (cd/m²).