In electrical pipe earthing systems, which type of pipe is commonly used as the main earth electrode (often connected near water supply systems)?

How does the ohmic value of the earth electrode resistance affect the overall effectiveness of a safety earthing system?

Consider the following statements regarding the specific purposes of materials used in the pipe earthing process: i. Charcoal is used to absorb and retain moisture around the electrode. ii. Common salt (NaCl) is added to increase the soil resistivity and provide mechanical stability. iii. The perforations in the GI pipe prevent the salt mixture from entering the soil, thereby reducing the effective surface area of the electrode. iv. The funnel is provided to allow the periodic addition of water to maintain moisture during the dry season. Which of the above statements are correct?