This standard specifies industrial terminal blocks (hereinafter referred to as terminal blocks) used in electrical circuits with a voltage of 600 V AC or less (frequency 50 Hz or 60 Hz) or 600 V DC or less. The terminal block referred to here is a combination of a conductive metal fitting with a wire connection part and an insulator that holds it for the purpose of connecting, branching, or relaying electric wires, and is mainly used for electrical control equipment, control panels, switchboards, etc. refers to something used inside.
JIS C 2811:1995 history
1995JIS C 2811:1995 Terminal blocks for industrial and similar use