Grounding and its notices were probed into construction of trolley isolative wire. How to eliminate safe hidden troubles in construction was discussed also.
This method does not need to untie the pole downlead then to carry on the earth resistance survey, has solved the biggest malpractice which in the existing measuring technique exists .
The too high impact direct current high pressure may reduce the resistance of trouble point too fast, even turn into a metalline earthing trouble, thus bring the trouble to appointed work.