Technical Terms

Ground (Earth) brings an electrical circuit into contact with earth by using a conductive material, such as a metal enclosure or conductor. There are three types of grounding: safety grounding, functional grounding, and lightning protection grounding.

Common (Common ground)is not a ground but a reference potential for circuit operation.

Safety grounding (protective grounding) is an essential mechanism that protects equipment, peripheral facilities, and users against electrical leakage or overcurrents in electrical products.

It ensures safety by directing the flowed electricity to the ground. In Japan, there are four Classes of safety grounding: Class A, B, C, and Class D. They are classified according to voltage and application.

Functional grounding provides the stable operation of electrical equipment. The ground is used as a point of zero potential, and the ground itself is used as part of the circuit to stabilize the operation of the circuit.

Lightning protection grounding is used to safely discharge the current generated by lightning from the lightning rod to the earth. The energy of the current caused by lightning is so great and dangerous that it can destroy equipment, buildings and harm people.

The lightning protection prevents damage by releasing the lightning current to the ground, which is crucial in designing and operating electrical and information systems.