The knife switch with rubber cover and porcelain pedestal is a kind of switching device  realizing operation by external force composed of knife switch and fuse protector (namely, the common protective tube or fuse wire). 

The function of knife switch is used for switching-on/off the circuit, and the fuse protector is used for protecting the load such as motor etc..It is commonly used for turning off/on the motor. The knife switch with rubber cover and porcelain base is used widely and it is used in power  utilization in industry and family. 

It consists of porcelain pedestal, incoming line pedestal, rubber cover, clip pedestal, fuse protector, blade of outgoing line pedestal (also called as moving contact), etc. 

The common knife switch with rubber cover and porcelain pedestal consists of HK1 series, HK2 series, HK1 series of products with national unified design, and the implication format of its model is:

HK *-*, eg. HK 2-63A, its important parameter is the numerical value 63A for “rated current” behind it. 

During installation of knife switch with rubber cover and porcelain pedestal, please pay attention to the following items:

Knife switch installation: In installation, the baseplate shall be perpendicular to the ground, and the hand shank shall switch on upwards. Don’t install reversedly or horizontally, because when the switch blade switches off the power supply, the blade and clip pedestal will produce electric arc (sparking), and when the hand shank switches on upwards, under the function of electromagnetic force and rising hot air, the electric arc is stretched upwards and is easy to extinguish. If it is installed reversedly, the arcing function of hot air is just opposite, which prevents electric arc stretching, affects arc extinction and easily makes the clip pedestal of blade burned out. In reversed installation, after the switch blade switch off, because of some kind of shake or the dead-weight of the switch blade, the switch blade will automatically fall, causing switch-on by mistake, which will make power failure parts charged again and affect the safety.

Wiring of knife switch:  It is required to connect the power supply to the incoming line pedestal above switch, and connect the leads of loads such as motor to the below outgoing line pedestal. In this way, after the switch blade is pulled open, no electric shock accident will be caused  when the fuse wire is changed. During wiring, tighten the screws too, otherwise, when the current gets through the joint of wires, high temperature will be produced because of large connecting resistance, thus making the connecting shrapnel “annealed” (the metal rigidity is reduced), and causing bad contacting or fire accident and fire to burn out load in severe case. In actual use, there are many single-phasing accidents of triphase load caused by the loosening of the contacting screws, special attention shall be paid.