What is NOT typically used as a grounding electrode in residential systems?

In residential electrical systems, grounding electrodes are critical for safety, providing a pathway for electrical faults to safely dissipate into the ground. Driven rods, metal water pipes, and well casings are all common grounding electrodes as they are typically in contact with the earth and can effectively conduct electrical currents.

Gas piping, however, is not typically used as a grounding electrode. This is primarily because gas piping systems are usually non-metallic or insulated to prevent corrosion and avoid any risk of ignition or explosion due to electrical faults. Additionally, grounding through gas piping could present safety hazards, as intrusive grounding can create potential differences that might energize the gas system, posing a significant risk for fires or explosions.

Therefore, the use of gas piping as a grounding mechanism is avoided, making it the correct choice for what is not typically used as a grounding electrode in residential systems.