Lighting fixtures contain two possible sources of ignition: the hot lamp surface and, should the lamp break, a hot filament that will burn out, producing a combination of intense heat and a spark. For this reason, this Rule requires all lighting fixtures for use in Class I, Zone 1 locations to meet the requirements of Rule 18-100.
We intend that lighting fixtures be approved as complete assemblies because if any part, including the lamp, is changed, the heating characteristics of the fixture may change and the maximum surface temperature of the fixture may be exceeded. Some fixtures are approved with a number of different globes and a number of different corresponding lamps. This information is then clearly marked on the fixture or the accompanying instructions, and it is the installer's responsibility to ensure that the completed assembly is approved. Most Class I fixtures have a connection chamber separated from the lamp chamber by a seal, and therefore qualify for the factory-sealed exemption.
PLUS 2203 HAZLOC-01
Hazardous Locations Guide for the Design, Testing, Construction, and Installation of Equipment in Explosive Atmospheres (Third Edition)
Lighting Fixtures (Luminaires)
Lighting fixtures of the incandescent, fluorescent, or other discharge types, except for low-pressure sodium types, are permitted in Division 2 and Zone 2. The fixtures must have no switches or starters unless they are sealed or non-incendive, and the maximum rating of the lamp must be marked.
The fixtures must be totally enclosed so that the lamp is not exposed to damage and unless the enclosure is electrically interlocked, a warning label must be attached indicating that the lamp must not be changed when the fixture is energized.
In addition, to qualify for Class I, Division 2 or Zone 2, the fixture must be subjected to a temperature test, in which the surface temperature of all of the components is measured, to determine the temperature code. This includes the surface of the lamp unless tests have shown that the lamp is not capable of igniting a gas or vapour/air mixture when run at its maximum rated voltage.
Electrical Safety Authority