Enclosure specifications for accommodation of intrinsically safe overvoltage suppressors in potentially
explosive areas
Overvoltage suppressors in hazardous areas must be installed in a metal enclosure or an
enclosure certified for the device application. If the application is in areas with combustible
dust, enclosure degree of protection IP6X shall be selected.
● Zone 1: Enclosure with degree of protection Ex e (increased safety)
● Zone 2: Enclosure with at least IP 54 (with manufacturer's declaration for Zone 2)
● Zone 21: dust-tight (certified) enclosure with degree of protection of at least IP 6x
● Zone 22: dust-tight (certified) enclosure with degree of protection of at least IP 5x
Testing the overvoltage suppressors used
Detection of n overload of the Blitzductor BXT ML4 BD EX 24 series overvoltage suppressor
before the overvoltage suppressor is destroyed is possible by means of the implemented
LifeCheck technology using test device DRC LC M3 (Part No. 910 653). Use of this test device
is only permitted outside the hazardous zone. Same as before, these Blitzductors have a fail-
safe function that generates a signal-type interruption when the overvoltage suppressor is
irrevocably destroyed, thus placing the downstream system out of operation but protecting it
from further overvoltages.
Appendix
A.5 Lightning and overvoltage protection
ET 200iSP
364
Operating Instructions, 11/2017, A5E00247483-07