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.
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
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 (email@example.com) edits the Certification department. For information about the CAP program, go to www.isa.org/CAP.