May/June 2011

ISA Certified Control Systems Technician (CCST) program

Certified Control System Technicians (CCSTs) calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables.

CCST question

Proper grounding of electrical devices is important for all of the following reasons, except:

A.        Safety

B.        Over-current protection

C.        Heat dissipation

D.        Electrical noise reduction

CCST answer

The correct answer is C, "Heat dissipation." Grounding practices do not address or affect heat dissipation in electrical circuits or components. Proper grounding provides safety, over-current protection, electrical noise reduction, lightning protection, and static electricity reduction. In each of these cases, proper grounding is important to provide a common reference voltage for electrical equipment and to provide a low-resistance pathway for stray currents and current surges to be carried away from electrical circuits. Proper grounding also prevents the buildup of excess charge, which can be harmful to equipment and dangerous to personnel.

Reference: Brown, D., Harold D., and Hope, R., Control System Power and Grounding Better Practice, (2004), Elsevier Press.