Grounding

Connecting the ground terminal of a power supply device to the earth with a wire. Grounding plays an important role in preventing electric shock by discharging abnormal voltage to the earth when the device becomes charged due to leakage current. Therefore, the grounding resistance, which is the resistance between the grounding terminal and the earth, is required to be low to allow current to flow easily to the ground. According to the Technical Standards for Electrical Installations, for low-voltage devices of 300V or less, the grounding resistance must be 100Ω or less (Type D grounding). In addition to preventing electric shock, grounding may also be implemented for noise reduction purposes.

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