10. Grounding system

10.2.1 Safety standards

For the design of grounding equipment, calculations must be made according to the curve in Figure 12 and the method defined in Annex B (Method of calculating permissible voltage).

In general, if the contact voltage requirements are satisfied, the stride voltage requirements are also satisfied. This is because the current path passing through the human body is different, so the step voltage limit that can be tolerated is much larger than the contact voltage limit.

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10.2.3 High and low voltage earthing systems

When high-voltage and low-voltage common ground systems are close to each other and there is no global grounding, some of the earth potential rise (EPR) in the high-voltage (HV) system may be conducted to the low-voltage (LV) system. Currently, both methods below are used.

a) Interconnection of high and low voltage earthing systems

b) Separation of high and low voltage grounding systems

In both cases, criteria such as stride length, contact and voltage limits must also apply to low-voltage electrical systems.

Typically, the interconnection method of high-voltage and low-voltage grounding systems is used.