Due to the high mineral contents of additives and enhancement materials (EMs), EMs have become popular in treating soil, which expectedly improves the electrical characteristics of soil. Much of the published work on the effectiveness of EMs is based on investigations at low magnitudes of voltage, current and frequency; however, the study of these EMs under high-impulse conditions has not been widely addressed. In this work, the experimental results of a small-mesh ground electrode without EMs and treated with EMs, where the latter was poured with a controlled amount of water, are presented. The impulse impedance was expected to change appreciably due to the ionic conduction in soil and the use of EMs with a high water content; however, the impulse impedance was found to be weak and dependent on the water content, and the inductive effect was found to be significant at the voltage and current decay times. This indicates that, even though EMs and highly wetted soil can reduce the soil resistivity and relative resistance value, special attention has to be given to the impulse characteristics of the ground electrodes, particularly at tail/decay times.

Grounding enhancement material (GEM) is used to lower the earthing resistance value of a given earthing system. In this paper, a commercially available GEM is experimented at the field alongside with Sodium Chloride, Copper II Sulphate and planting soil. The well established Wenner’s 4 pole method and fall of potential method was employed to measure the soil resistivity and earthing resistance respectively. It was found that the salts i.e., Sodium Chloride and Copper II Sulphate are superior in reducing the earthing resistance as reduction of more than 85% were observed. However, the commercial GEM has exhibited the most stable earthing resistance value over a period of 101 days, exhibiting the lowest standard deviation. This seems to suggest that the commercial GEM has superior moisture retention capability. This study also proven that Sodium Chloride can be dissolved by heavy downpour and replenishing it periodically is needed in a tropical country like Malaysia with regular thunderstorms and heavy downpours.

Among the factors that affect the soil resistivity is the chemical content in soil, where the ionic conduction is expectedly increased and the soil resistivity is reduced. Due to the beneficial use of chemical composition in soil, enhancement materials (EMs) or salts have been widely used in an effort to obtain a low ground resistance value. Much published data on the performance of the EMs on the steady-state resistance value is available; however, not much data is available on its characteristics under high impulse conditions by field measurements. In this paper, experimental test results on twelve configurations (six configurations with the EM and without the EM) installed in situ and tested under impulse conditions are reported. The study aims to quantify the effects of ground electrode configurations and EM on the soil characteristics under high impulse conditions, providing valuable insights for optimising grounding system design. Results show that the steady-state ground resistance is reduced by over 40% for most configurations with EM, significantly improving the current discharge time under impulse conditions. Additionally, inductive effects were more pronounced in configurations with lower resistance, particularly at higher voltages, while the impulse impedance was current-dependent for configurations without EM, whereas those with EM were less affected by current magnitude. CDEGS simulations indicated that parallel configurations are more prone to inductive effects than grid configurations, with electrode shape having a greater influence than size.

Regarding the installation of grounding systems, it is not common for the installation site to be re-located due to high soil resistivity. Enhancement materials have been widely used for their known advantages, including their ability to reduce the resistivity of soil. Although some studies have been conducted on the characterization of EMs under AC of various frequencies, limited studies can be found on their performance when mixed with various percentages of water content (WC) and soil. In this work, sand mixed with controlled percentages of enhancement materials (EM 1, EM 2 and EM 3) and controlled amounts of water content was placed on a parallel plate and tested under AC of various frequencies to obtain the resistivity and permittivity. It was found that dry sand–EM mixtures can be represented by an R-C parallel circuit, while wet sand–EM mixtures can be represented by a nonlinear R. These new test data providing the soil resistivity and permittivity of various sand–EM mixtures are important in selecting suitable EMs to be used in grounding systems.

One of the requirements for the safe operation of customer premises equipment (CPE) is an adequate grounding system as a means to divert high fault currents to the ground. In this work we report on the results of an experimental study of the impulse characteristics at a charging voltage of 30 kV on the surge protective device connected to 16 earth electrodes and installed at two sites, giving various ground resistance at low voltages, R_DC values. All of these grounding electrodes were installed and tested under the same charging voltage to determine the effectiveness of ground electrodes toward the damage of a modem at the premises. We observed that modems did not experience damage when the ground electrode of the distribution pole (DP) had an RDC below 30 Ω in general and below 46 Ω when ground electrodes installed in low resistivity soil were used. The impulse polarity did not affect the damage susceptibility of the CPE.

In addition to the soil resistivity and size of the grounding system, grounding system configuration can influence the steady-state resistance (RDC) of a grounding system. The RDC of four to six configurations in three distinct soil conditions (sites 1 to 3) is measured using the fall-of-potential method and computed using the current distribution, electromagnetic fields, grounding, and soil structure analysis (CDEGS) simulation. The RDC value generally decreases as size increases, i.e., when more rods or tapes are added, except for a little variation subject to the electrode arrangement and soil resistivity. The 3 and 4-parallel configurations perform better on low resistivity soil (site 1), while the grid configurations (2×2- and 3-rod grids) are better on high resistivity soil (site 2). The difference between the measured and computed values at high soil resistivity sites (sites 2 and 3) is large, ranging from 18% to 66% for site 2 and from 35% to 53% for site 3. The difference is lower and more consistent at site 1, where five out of six configurations achieve less than 10%. At all sites, the difference between computed and measured RDCs generally decreases as the area of the electrode increases, except for some cases at site 2.