The utility model provides a stable intelligent protective earthing case of ground connection, last voltage testing and the infrared probe installed of grounding box to and be used for connecting thetreater of voltage testing and infrared probe, and lead the electrolyzer cooperation through three -phase plug -in strip and combined floodgate, realize three -phase plug -in strip ground connection,realize connecing grounding resistance disconnected through installation baffle on the mounting panel lead electrolyzer symmetrical arrangement for the combined floodgate. In the use, infrared probe detects personnel and is close to, have voltage if the low pressure main line is current, then the baffle closes, realizes unable ground connection, has realized that safe back brake and circuit examine and repair, avoids the operation of mistake coincidence plug -in strip, the effectual emergence that prevents circuit short circuit matter, if there is not the magnitude of voltage, then realize theground protection. Through installing the plug -in strip mount pad in the top of ground connection mounting panel, utilized the gravity of three -phase plug -in strip to improve the stability of three -phase plug -in strip ground connection, improved the reliability of grounding box ground connection for the grounding box during operation is safer.