Dad Andrew Fenwick, 66, had been using a metal wrench to fix the pump next to the pool at their home in Rayong, Thailand, according to local reports.
But engineer Andrew – who was Australian but was born in Devizes in Wiltshire and retired to Thailand after working in the UK – was electrocuted by a suspected water leak among the cables.
His son, Jason, is then believed to have been killed when he ran to help his father – after stepping in a puddle which conducted electricity which surged through his body.
Andrew’s other son, four-year-old Justin, is reported to have witnessed the accident and ran crying into the street for help at 4.30pm yesterday afternoon (10.30am UK time).
He was found by local security guard Komin Jittiworaphan, 51, who called police.
Andrew’s Thai wife, Somrudi Krailob Fenwick, 41, was alerted by neighbours and she returned home – breaking down in tears at the poolside.
She told police that she was not in the house at the time of the accident but came home after neighbours found the bodies.
She said: “This is terrible. I’m heartbroken. My husband and son gone at the same time.
“Andrew was so confident with tools, he was an engineer. I don’t know how this has happened.
“I cannot understand it. Life is so cruel to take them both.”
Rescue workers cut the power supply at the home before officers removed the bodies for post mortem examinations.
Pol Capt Kaweewuth Boonruang, deputy investigation inspector at Rayong Muang police station, said: “There were two deaths caused by electric shock.
“According to the investigation, the two dead were father and son of Australian citizenship.
“The father was repairing the pump of the pool in the pump house next to the pool.
“The son saw the incident and ran to help not knowing there was a leak and he was electrocuted.
“He had burns from the fire on his hands, his body and his face.”