接地保护一般用于配电变压器中性点不直接接地（三相三线制）的供电系统中，用以保证当电气设备因绝缘损坏而漏电时产生的对地电压不超过安全范围。如果家用电器未采用接地保护，当某一部分的绝缘损坏或某一相线碰及外壳时，家用电器的外壳将带电，人体万一触及到该绝缘损坏的电器设备外壳（构架）时，就会有触电的危险。相反，若将电器设备做了接地保护，单相接地短路电流就会沿接地装置和人体这两条并联支路分别流过。一般地说，人体的电阻大于1000欧，接地体的电阻按规定不能大于4欧，所以流经人体的电流就很小，而流经接地装置的电流很大。这样就减小了电器设备漏电后人体触电的危险。
The grounding protection is generally used in the power supply system where the neutral point of the distribution transformer is not directly grounded (three-phase three wire system), to ensure that the ground voltage generated when the electrical equipment leaks due to the insulation damage does not exceed the safety range. If the household electrical appliances are not grounded, when some part of the insulation is damaged or a phase line touches the shell, the shell of the household electrical appliances will be electrified. If the human body touches the shell (frame) of the electrical appliances with the insulation damage, it will be in danger of electric shock. On the contrary, if the electrical equipment is grounded, the single-phase ground short-circuit current will flow along the two parallel branches of the grounding device and the human body. Generally speaking, the resistance of the human body is greater than 1000 Ω, and the resistance of the grounding body cannot be greater than 4 Ω according to the regulations, so the current flowing through the human body is very small, while the current flowing through the grounding device is very large. This reduces the risk of electric shock to human body after electric leakage of electrical equipment.