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4.    Lamps

Lamps are devices for obtaining light from electricity.

Lamps can be classified into 3 main categories namely: incandescent-filament lamp, gaseous discharge lamp, and mercury blended-light lamp.

(a) Incandescent-Filament Lamps (Figure 5)

Light is produced by means of a filament of carbon, tungsten, or other metals, heated by an electric current


Figure 5 Incandescent Lamp

(i) Higher Efficacy : the luminous efficacy is the ratio of the luminous flux emitted from the lamp to the power consumed, the unit being lumen/watt.

(ii) Longer Life : the filament in an incandescent lamp evaporates as it is heated

Incandescent-filament lamps can be further divided into two types, according to the atmosphere inside the bulb:

(i) General Lighting Service(GLS) Lamps

ii) Halogen (TH) Lamps


(b) Gaseous Discharge Lamps

These include high/low pressure mercury vapour lamps, high/low pressure sodium lamps, and mercury halide lamps.

(i) Low Pressure Mercury Vapour (Fluorescent) Lamps

(ii) High Pressure Mercury Lamps (MBF) (Figure 6)

Figure 6 High Pressure Mercury Lamps


(iii) Low Pressure Sodium Lamp (SOX)

(iv) High Pressure Sodium Lamps (SON, SON-L, SON-R)

(v) Mercury Halide Lamps (MBI)


(c) Mercury Blended-Light Lamps


Figure 7 Summary of Lamp Types & their Characteristics


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