The standard unit of a surface being lit is calculated as Lux. One Lux is one lumen per square meter.

Light output Ratio (L.O.R.):
The ratio of the total light emitted by a luminaries to the total light output of the lamp (S) it contains. The light output ratio is always less than 1.

Lumen Depreciation:
Decline of light output of a light source during its lifetime.

The Light intensity per square meter of apparent area of the light source, Luminaire or illuminated surface (cd/m). Where surface are lit, the luminance is dependent on both the lighting level and reflection characteristics of the surface itself.
Unit: cd/m2
Symbol: L

Luminous Efficacy:
The quantity of the light a light source emits per watt of electrical power of energy consumed. Note that both the lamp luminous efficacy and the system (lamp and ballast) luminous efficacy can be specified. The system luminous efficacy is always lower than the lamp luminous efficacy.

Luminous Flux:
The total light output emitted by a light source, Also the total light falling on the surface. Light output of a light source is measured in lumen.
Unit: lumen
Symbol: Ø

Luminous Intensity:
The luminous flux in a given direction (e.g. from a floodlight, projector).
Unit: candela (cd) = one lumen per steradian.
Symbol: l


Suggestive Lux Level

Checking desks, Ticker counters, Information desks 500
Departure lounges 200
Baggage handling 200
Customs and Immigration halls. 500
Building Area
Entrance hall, Waiting rooms, Lobbies 200
Enquiry desks 500
Cafeterias, Dining rooms, Mess rooms 200
Ramps and Corners 30
Entrance and Exits 100
Super Markets, Hyper-Market 500
Showrooms 700
Show Window 1000
Cinema and Theatres
Foyer 200
Booking office 300
Auditorium 100
General/Reception/Waiting 300
X-Rays areas 200
Consulting room 100
Reception 300
Grill rooms, Restaurants lounges 200
Bed rooms 100
Bath room 150
Libraries/ Museums
Libraries/Reading rooms 300
Museums and Art galleries 300
Conference/ Reception rooms 300
Classrooms 150
Living rooms 150
Casual reading/ Desk and prolonged reading 300




IP ingress protection Standards

IP Protection against ingress of solid bodies, dust and moisture:

The ingress Protection system (IP) EN 60529, 1991 defines various degrees of protection against the ingress of foreign bodies, dust and moisture. The term foreign bodies’ includes things like fingers and tools coming into contact with the electrical live parts of the luminaries.

Both safety aspects (contact with live parts) and harmful effects on the function of the luminaire are defined. The exact testing method for each IP classification is described in EN 60529.

Note that the conditions during testing might differ from the specific conditions in an application. The designation to indicate the degree of protection consists of the characteristic letters IP followed by 2 digits indicating conformity with the conditions stated in two tables.

It is important to realize that the specification and safety of lumiaires are only secured if the necessary maintenance accourding to the instructions of the manufacturer is carried out in time . Luminaires are not available in all possible combinations of ingress and moisture protection. The most common applications of the IP classifications for luminaires are:

IP 20:

Luminaires which can be applied indoors only if no specific pollution rates are expected. Offices, dry, heated industrial halls, shops, shopping malls and theatres are typical application segments.

IP 21/22:

Luminaires which can be applied in unheated (industrial) halls and under canopies as the luminaires are drip-and condensation-water-protected.


Luminaires which can be applied in unheated industrial halls or outdoors.

IP 43/44:

Luminaires and bollards for outdoor street lighting and street lanterns. Bollards mounted at a low height are protected against small solid objects and against rain and splash. A common combination within an industrial high-bay luminaire or street lantern is IP 43 For the electrical part of the luminaire, to secure safety, and IP 54/66 for the optical part of the luminaire, to prevent pollution of reflector and lamp.

IP 50:

Luminaires which are applied in dusty environments, to prevent rapid pollution of the luminaire.The exterior of IP 50 luminaires can be cleaned easily. In the food industry. Closed luminaires are specified to prevent glass particles from accidentally broken lamps entering the production area contaminating the products under preparation.

Although ingress protection is specified to protect the luminaire function it also means that particles cannot leave the luminaire housing, thereby meeting the specification of the food industry. In the ‘wet’ food industry, luminaires meeting the IP 50 classification shall not be applied.

IP 54:

The traditional water-protected classification. Luminaires can be cleaned with water without any harmful effect. this classification is often specified in the food processing industry, for industries where dust moisture are generated in the hall, and for use under canopies.

IP 60:

Luminaires which are completely sealed against dust accumulation, and are used in very dusty environments (wood and textile industry, stone carving ) and in the food industry as axplained above. IP 60 luminaires are rarely applied: IP 65/IP 66 is usually applied instead.

IP 65/66

Jet-proof luminaries which are applicable where the surroundings are hosed down frequently by water jets, or where luminaires are applied in a dusty environment. Although the luminaires are not fully watertight, the potential ingress of moisture will not have any harmful effect on the luminaire function. IP65/66 luminaires are often available in impact-protected versions.

IP 67/68

Luminaires complying with this classification are suitable for immersion in water. Typical application areas are underwater lighting of swimming pools and fountain lighting. Deck lighting on ships should also meet this classification. The test method does not impty that IP 67/68 luminaires meet the IP 65/66 classification as well