Which electrical component cannot act as a grounding electrode according to safety standards?

In the context of grounding electrodes, safety standards dictate that a suitable grounding electrode must be conductive and able to effectively dissipate electrical energy into the ground. Metal underground gas piping fulfills this criterion because it is conductive and often grounded to ensure safety against surges or lightning strikes, making it functional as a grounding electrode.

On the contrary, plastic piping systems do not conduct electricity, which makes them ineffective for use as grounding electrodes. Wooden telecommunication poles and metal underground tanks can potentially act as grounding electrodes, but their effectiveness can vary depending on their environment and installation specifics. Therefore, the choice that stands out as not meeting the safety standards for grounding electrodes is plastic piping systems due to their non-conductive nature.