V. Temperature classification of equipment
Group II equipment is classified according to the maximum permissible surface temperature as follows:
1)  Т1 - 450 degrees Celsius;
2)  Т2 - 300 degrees Celsius;
3)  ТЗ - 200 degrees Celsius;
4)  Т4 - 135 degrees Celsius;
5)  Т5 - 100 degrees Celsius;
6)  Т6 - 85 degrees Celsius.

ТР ТС 012/2011
Annex  2
to the Technical Regulation of
the Customs union «On safety of
equipment intended for use in
explosive atmospheres»
(ТР ТС 012/2011)
Drawing of special Explosion Safety Mark

Description of special Explosion Safety Mark drawing
Explosion Safety Mark drawing consists of two conventionalized Latin letters «Е» and «х». The height of letter «х» shall be 5/9 of letter’s «Е» height. The letters are inscribed in the rectangle on the light (Fig.1) or hard (Fig.2) background with height-to-width aspect ratio 11/8.
Ех stands for explosion protection (Explosion-proof).
The size of the special ex-marking shall be determined by the manufacturer of the equipment for use in explosive atmospheres. The coordinating dimension of the rectangular shall be not less then 10 mm. the size of the special ex-marking shall ensure legibility of its components and distinguishability with an unaided eye on the overall color background of equipment or Ex-component.