The mechanical strength of glass insulator surface is high, which makes the surface not easy to crack. Generally, the electrical strength of glass remains unchanged during the whole operation period, and its aging process is much slower than that of porcelain. Therefore, glass insulator is mainly scrapped due to self damage, which occurs in the first year of operation, but the defects of porcelain insulator are only found after several years of operation.

If glass insulator is used, regular preventive test on live line of insulator during operation can be cancelled. This is because each kind of damage of toughened glass will cause damage to the insulator, which is easy to be found by the operators during the line inspection. When the insulator is damaged, the glass fragments near the steel cap and iron foot are stuck, and the mechanical strength of the remaining part of the insulator is enough to prevent the insulator string from breaking.