1. For a ground to be an effective ground it must have a low resistive path to earth
(or the conductive surface used as earth).
2. What National Electrical Code (NEC) Article governs grounding?
3. Potential is measured in volts.
4. Lightning is a form of ESD.
5. DC Control voltage (24 V or less) must be grounded.
What are your answers before you read ahead?
From the ISA Course Electrical Noise Effects on Instrumentation Control Equipment (TI21) pre-instructional survey.