XI'AN - A boy suffered a near-fatal electrocution when he urinated on a transformer on a roadside in China's Xi'an, the capital of Shaanxi province.

Fang Haohao, seven, wanted to relieve himself on May 16 while waiting with his parents at a bus stop and was told by his father to do so at an open space behind some hoarding, according to My Paper.

Mr Fang then heard crackling noises shortly after and saw thick smoke rising from a nearby shed, which turned out to be a 10,000-volt electrical substation.

He rushed over to discover his son lying on the floor of the shed, his whole body on fire. All the boy's hair had been burnt off and he was covered in blisters.

Haohao was rushed to a hospital, which transferred him to a better-equipped facility where his left arm was amputated. A doctor also said nearly half of the boy's body was severely burnt and that his skull was visible.

Police on the scene discovered a small warning sign on the shed but was unable to establish who owned it.

Speaking to local media, a tearful Mr Fang questioned the lack of prominent warning signs around the substation. He also asked why it was located so near a bus stop.

"We come from a village. My son must have thought it uncivilised to pee by the roadside in a city. But at his age, how could he have known that it was a substation?" he said.

Quoting a physics teacher in Xi'An, My Paper reported that urine, consisting mostly of saline, is a good conductor of electricity.

An electrical current could have flowed through the boy's stream of urine if it came into contact with the transformer, causing an electric shock.