Practice Questions for the CompEx Exam

16. Increased safety Ex `e` apparatus is designed to contain an internal explosion
a. True
b. False
c. True, providing barrier glands are used
d. True, providing the IP rating is at least IP54

17. In general, Ex `e` equipment can be installed in
a. Zone 0
b. Zone 1 and 2
c. Zone 0, 1 and 2
d. Zone 2 only

18. Ex `e` equipment can be installed in are requiring
a. Equipment to EPL `Ga` and `Gb`
b. Equipment to EPL `Ga`, `Gb`, and `Gc`
c. Equipment to EPL `Ga` or Category 1
d. Equipment to EPL `Gb` and `Gc`

19. Ex `e` equipment must have an IP rating of
a. IP 54
b. At least IP 54, but location conditions may require a higher value
c. IP 44
d. At least IP 44, but location conditions may require a higher value

20. Locknuts on an Ex `e` equipment are
a. Always required
b. Never required
c. Required on clearance holes
d. Required on 10mm thick threaded entries

21. In general, Ex `n` equipment can be installed in
a. Zone 0
b. Zone 1
c. Zone 2
d. Clear areas

22. Ex `n` equipment can be designed for
a. Group II
b. Group IIA and IIB
c. Group IIA only
d. Group IIB only

23. Which is not a recognised Ex `n` method of protection
a. Type A Non-sparking
b. Type d Flameproof
c. Type L Energy limited
d. Type R Restricted breathing
e. Type C Sparking with hermetically sealed, enclosed break or encapsulated

24. When terminating a cable into an 8 mm thick type `n` metal enclosure with a threaded entry, which of the following is required?
a. Locknut
b. Star washer
c. IP washer
d. None of these

25. For Ex `n` restricted breathing, which one of the following must always be provided?
a. IP washer
b. L:ocknut
c. Earth tag
d. Threaded entry

26. Ex `ia` equipment can be installed in
a. Zone 0
b. Zone 1
c. Zone 2
d . Clear area

27. Galvanic isolators require
a. An intrinsically safe earth connection
b. At least two Zener diodes
c. A device providing electrical separation such as a transformer, relay or opto-coupler
d. At least three Zener diodes

28. Which of the following does not require an intrinsically safe dedicated earth?
a. Zener barrier with two Zener diodes
b. Galvanically isolated barrier
c. Zener barrier with three Zener diodes
d. Zener barrier supplying simple apparatus

29. What is the minimum distance between terminals for intrinsically safe circuits and terminals of non-intrinsically safe circuits?
a. 100 mm
b. 50 mm
c. 6 mm
d. 3 mm 30.

What is the minimum clearance to earth (intrinsically safe circuits)?
a. 100 mm
b. 50 mm
c. 6 mm
d. 3 mm