1 July 2005

ISA Certified Automation Professional (CAP) program

This question is from the CAP study guide, Performance Domain III, System Design.

Definition: Design, specify, and procure the hardware/software used in the system.

CAP question

Which of the following protection techniques is acceptable for equipment located in a Class I, Division 1 area?

A. Explosion-proof apparatus and non-incendive equipment

B. Explosion-proof apparatus and intrinsic safety

C. Dust ignition-proof and non-incendive equipment

D. Hermetically sealed and intrinsic safety

CAP answer

The best answer is B, explosion-proof apparatus and intrinsic safety.

Hazardous location protection techniques are defined by NEC 500.7 (NEC 2002 Code). The protection techniques are permitted as follows:

  • Explosion proof apparatus-Class I, Division 1 or 2
  • Intrinsic safety-Class I, Division 1 or 2; Class II, Division 1 or 2; or Class III, Division 1 or 2
  • Nonincendive equipment-Class I, Division 2; Class II, Division 2; or Class III, Division 1 or 2 (does not include Class 1, Division 1)
  • Dust ignition proof-Class II, Division 1 or 2 (does not include Class I, Division 1)
  • Hermetically sealed-Class I, Division 2; Class II, Division 2; Class III, Division 1 or 2 (does not include Class I, Division 1)

Reference: Earley. NEC Handbook, 2002 edition, NFPA, 2002.

Nicholas Sheble (nsheble@isa.org) edits the Certification department. For information about the CAP program, go to www.isa.org/CAP.