Marking of explosion protected electrical apparatus


In addition to the standard data (make, type, serial no., electrical data), data concerning the explosion protection have to be included.

In the U.S the following data to be included for explosion protected electrical apparatus to NEC 500-2:
a) Class: Marking of the area of application (atmospheres where gases, vapors, dust of fibers exist)
b) Group: Classification to the explosion characteristics of the materials for which the apparatus is suitable.
c) Temperature or Temperature identification number: max. exposed temperature or temperature range (temperature class).

FM additionally requires the marking of the designated division for intrinsic safety approval.

The European standards require the following marking similar to the IEC recommendations:


			EEx	d	Iib	T3

EEx: - symbol for apparatus built to European standards:
d :- abbreviation for the type of protection used.
Iib :- group of electrical apparatus of explosion group for which it is certified.
T :- temperature class.
In addition the testing station and the number of the test certificate or certificate of conformity has to be stated,