DALI  (Digital Addressable Lighting Interface) is a standardized digital interface for electronic ballasts operating fluorescent lamps. Unlike the analogue interface (1-10 V) it supersedes, DALI can address and control operating devices individually.

Degree of protection

The degree of protection assigned to a luminaire is a guarantee of safe and reliable operation. The IP code (standing for "Ingress Protection") consists of two numerals. The first (1 to 6) indicates the degree of protection against solid foreign bodies, the second (1 to 8) attests to the degree of waterproofness. Higher degrees of protection include those lower down the scale. Where one of the two numerals is missing, its place is taken by a capital "X", which means "untested".


Dimming enables the brightness of individual lamps or groups of lamps to be controlled. It changes the lighting atmosphere, permitting adjustments to suit different room uses (comfort dimming). Increasingly, dimming is also used to save energy (power dimming), e.g. in daylight-dependent office or factory lighting systems.

DIN 5035

Prior to the introduction of European standards (EN), which apply across the whole of the European Union, DIN 5035 "Artificial lighting of interiors" was the principal lighting standard in Germany. Some of the eight parts of this standard still apply today, in their original or a revised form. The list is as follows:  

DIN 5035 Lighting with artificial light

Part 1 Concepts and general requirements (entirely superseded in September 2002 by DIN 12665)

Part 2 Guideline values for indoor and outdoor workplaces (largely superseded in March 2003 by DIN EN 12464-1)

Part 3 Lighting in hospitals (largely superseded in March 2003 by DIN EN 12464-1; DIN 5035-3 has applied as a supplementing standard since its revision in July 2006)

Part 4 Special recommendations for lighting in educational establishments (largely superseded in March 2003 by DIN EN 12464-1)

Part 5 Emergency lighting (entirely superseded in July 1999 by DIN EN 1838)

Part 6 Measurement and evaluation

Part 7 Lighting for rooms with VDU workstations and workplaces with VDU facilities (partly superseded in March 2003 by DIN EN 12464-1; DIN 5035-7 has applied as a supplementing standard since its revision in August 2004)

Part 8 Special requirements for task lighting in offices and office-like rooms.

DIN EN 12464

DIN EN 12464 "Light and lighting – Lighting of work places, Part 1: Indoor work places" (DIN EN 12464-1 for short) is the European lighting standard that superseded large parts of the national standard DIN 5035 in March 2003. DIN EN 12464-2 "Light and lighting – Lighting of work places, Part 2: Outdoor work places " (DIN EN 12464-2 for short) has applied since October 2007.

DIN EN 1838

DIN EN 1838 "Emergency lighting" applies throughout the European Union. In Germany, it supersedes national standard DIN 5035 Part 5.

Direct/indirect Lighting

A combination of direct and indirect lighting in a room is generally found agreeable. This can be provided by using luminaires designed solely for direct lighting in conjunction with models designed exclusively for indirect lighting. However, there are also many luminaires available which combine direct and indirect lighting in a single light fitting: pendant surface-mounted ceiling luminaires and standard luminaires. As a general rule, most of the light cast by these luminaires is indirect (cast onto ceiling or walls); direct lighting is provided by an additional light exit underneath.

Direct lighting

Direct lighting is where luminaires cast their light directly into the room onto surfaces or zones where light is needed.

Deep drawn thermoforming

Thermoforming process in which the sheet being formed under a deep draw ratio can slide inwards during the forming process and takes on the shape of the mould.