CSLB C-46 Solar ContractorPhotovoltaic System InstallationMedium
A solar technician is performing a ground continuity test on a newly installed PV array. They are using a multimeter to check the resistance between the module frames, racking system, and the main grounding electrode conductor. What is the acceptable resistance reading for a properly grounded PV system?
- AAs close to 0 ohms as practically possible.
- BInfinite resistance (open circuit).
- CBetween 100-500 ohms.
- DGreater than 1000 ohms.
Show answer & explanationAnswer & explanation
Correct answer: A. As close to 0 ohms as practically possible.
For proper grounding and electrical safety, all metallic components of a PV array and racking system must be bonded together and to the main grounding electrode conductor with as low resistance as practically possible, ideally approaching 0 ohms, to ensure effective fault current path.
Why the other options are wrong
- B. Infinite resistance indicates an open circuit, meaning no ground path, which is unsafe.
- C. 100-500 ohms is too high for proper equipment grounding, which needs a very low impedance path.
- D. Greater than 1000 ohms (1 kilohm) is an extremely poor ground connection, posing a significant safety hazard.
PV System Grounding Resistance
The measured electrical resistance of the grounding path from metallic PV system components to the earth, which should be as low as possible for safety and fault current protection.
- Crucial for electrical safety and fault current clearing.
- Resistance should be near 0 ohms (typically <1 ohm for practical purposes).
- Tested with a multimeter or specialized earth ground resistance tester.
Memory trick: Grounding: Zero Ohms for Safety