The unit is sealed and should not be operated if either the plastic or glass is cracked or broken. Lamp disposal should be treated in the same way as for fluorescent lamps.

How an Induction Lamp Works
Light generation is on the same principle as a fluorescent lamp. An electrical current passing through a low pressure of mercury vapour produces UV radiation. This is absorbed by the phosphor coating and emitted as light.

The fundamental difference is there are no electrodes or wire connections into the lamp. Induction lamps are sometimes called "electrodless" lamps because of this feature. The glass bulb has a hollow centre and in this there is an induction coil, which is connected to a high frequency supply generated by control gear mounted in the lamp cap.

It is the changing magnetic field within the lamp that generates the current flow through the ionised mercury vapour.

Electrodes absorb energy and so reduce the lamp efficacy. They also cause local blackening on the lamp wall which reduces light output. The coating on the conventional electrodes is vital to the starting process and when it has been used the lamp will fail to start. The electrodes are thus a major factor in determining lamp life. Finally the wire connections through the glass have to form a gas tight seal and this complicates lamp construction and is a possible cause of failure. The principal benefit of induction lamps is their similar appearance to conventional R80 reflectors - this is impossible with compact fluorescent lamps (CFLs).

The induction process eliminates these components and thus changes the life characteristics of the lamp. GE recommend an economic life for Genura of 15,000 hours, at which time the light output will have fallen to about 75% of the initial lumens. This reduction in lighting performance should justify lamp changing for most applications. However after 15,000 hours there will be very few physical failures so lamp reliability is excellent. We predict that failures are more likely to be in the electronics than the bulb. As in normal fluorescent lamps the light degradation eventually makes the use of the bulb uneconomical.

Figure 7.3. Lumen maintenance of Genura lamp.