Associated apparatus not suitable for installation in a hazardous area will be certified and marked with the Ex symbol and the type of protection, all within the same square brackets:
e.g. [Ex ia] IIC
For associated apparatus suitable for installation in a hazardous area, and where the energy limitation is provided inside the equipment in the hazardous area, the symbols of the type of protection are enclosed within square brackets:
e.g. Ex d [ib] IIC T5 or Ex px [ia] IIB T4
This marking would means; the enclosure is flameproof and contains associated ‘intrinsically safe’ equipment.
Certified intrinsically safe field equipment, for mounting in the hazardous area, will be marked with the type of protection in the normal way:
e.g. Ex ia IIC T6 Ex ib IIC T5 Ex ic IIB T4
Simple Apparatus is not required to be marked.
