Which condition primarily affects ground resistance in a ground rod installation?

In a ground rod installation, ground resistance is influenced by multiple factors, and the correct choice encompasses all the significant conditions affecting it.

Soil type is crucial because different types of soil have varying conductive properties. For instance, sandy soils typically have higher resistance compared to clay soils, which are more conductive due to their moisture retention and mineral content.

Temperature can also affect resistance because the conductivity of soil changes with temperature. As soil warms up, its resistance can decrease, improving the efficacy of the grounding system.

Moisture content plays a pivotal role as well. The presence of moisture directly affects the soil's conductivity; wetter soils generally have lower resistance, which allows for better grounding performance.

Since all these factors—soil type, temperature, and moisture content—interact and contribute to the overall ground resistance, the most comprehensive and accurate choice is that all of the above conditions affect ground resistance in a ground rod installation.