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Lighting explained

A GUIDE TO COMMONLY USED TERMS WITHIN LIGHTING
For full information on understanding lighting performance, visit jcc.co.uk/lighting-explained

1 Wattage (VA)
4 Lumens per circuit Watt (LpcW)

Distance from fitting 1 metre 2 Lumens 3 Light Output Ratio

2 metres 200 lux

5 Lux

3 metres
150 lux

1 WATTAGE (VA)
A measure of the energy consumed by a fitting
A measure of power or the rate of energy consumption by an electrical device when it is in operation, calculated
by multiplying the voltage at which an appliance operates by the current it draws (Watts = Volts X Amperes).

2 LUMENS
A measure of light output
A lumen is a unit of measurement that is used to express how much illumination a source of light provides.

3 LIGHT OUTPUT RATIO (LOR)
The proportion of light that finally leaves the light fitting
This is a measure of the efficiency of the fitting and is a ratio of the lumens leaving the light source and the
lumens that finally leave the fitting.

4 LUMENS PER CIRCUIT WATT (LPCW)
The efficiency of the fitting

A calculation of the efficiency of a fitting. Lumens (3000) ÷ Wattage (50W) = 60 LpcW
5 LUX
A measure of light intensity
A measure of the intensity of light as seen by the human eye and measured by luminous flux per unit area.
One lux is equal to one lumen per square metre.

248 Technical jcc.co.uk