Simplified conservative measurements of touch and step voltages

Protection against electric shock requires grounding systems that must be designed primarily to keep touch voltage (E_t) and step voltage (E_s) to a safe value. Testing of the efficiency of a grounding system is mandatory to verify the capability to satisfy the protection requirements at the end of the construction and periodically in the following. With urban development and buildings growth adjacent to power systems, grounds systems that are not metallically connected may often be found. They are thus significantly interdependent as they are located in each other´s area of influence and particularly it is useful to consider ground potential difference (GPD). It becomes increasingly difficult to choose suitable locations for test probes to make resistance, E_t and E_s tests of a grounding system. Accuracy of tests requires reaching remote earth and for large grounds the spacing required may not be practical or even possible. Unfortunately accurate measurement is often unfeasible, owing to the additional difficulty to measure both the hazardous voltages of the ground system, where test ground current flows, and the hazardous voltages of influenced ground systems. Since the rigorous measure can result too much laborious or too much expensive, a simplified conservative testing method of the behavior of ground electrodes can be favorable. This paper discusses an approach to the above-simplified testing method, which relies on single, or multiple auxiliary electrodes placed at short distance from the grounding system. By means of this approach, a conservative test can be made of both E_t and E _s GPD