An undated photo shows Zhao Wenwu working in Dalian, Northeast China's Liaoning province. [Photo provided to chinadaily.com.cn]

He walks for hours on cables that are 100 meters above the ground in scorching heat and freezing winter in gear that weighs two kilograms. And these are not some ordinary cables. They carry high-voltage electricity.

Meet Zhao Wenwu, an electric power transmission worker at Dalian Power Supply Company subordinated to State Grid Corporation.

"I have to make sure that not a single mistake happens, because if it does, it means someone could lose their life," said Zhao.

Zhao, 48, has worked as a "doctor" fixing malfunctioning high-voltage and extra-high-voltage cables for 28 years.

He now leads a seven-member team responsible for detecting and overhauling 153 cables, totaling 1,300 kilometers, that transmit electricity for Dalian, a city with nearly seven million population in Northeast China's Liaoning province.

Facing flowing high-voltage electricity and variable weather while staying on high cables, which range from 20 to 100 meters high for different voltages, in the air for hours, Zhao has one of the most dangerous and demanding jobs in the power sector.

An undated photo shows a member of Zhao's team working on high-voltage cables in the air in Dalian, Northeast China's Liaoning province. [Photo provided to chinadaily.com.cn]

A typical working day for Zhao and his teammates starts like this:

Carrying several kilograms of tools and equipment, they walk several kilometers in the wild and reach the foot of a transmission tower.

Some of the team members put on airtight protective clothing, which weighs about two kilograms, and safety belt, and climb up the tower, while the rest stay on the ground as back up.

On the top of the tower, climbers catch a breath and prepare to send one of them to the trouble spot of the cable. The dispatched worker will either take a ride on a pulley cable vehicle or walk on a cable with hands holding on two other cables, just like wire-walking, to reach the spot.

"An ordinary person may quit halfway before reaching the trouble spot because he will run out strength or due to fear of height," said Zhao, adding that the whole process sometimes takes hours depending on the height of the tower.

But the dispatched worker will work on the cables for several hours without eating, sometimes even without drinking, and fix faults on the dangerous metal cable or other heavy equipment even if he is already tired. It usually takes workers half a day, although for some difficult problems it could take up to seven hours, to finish a task.