The burnt remains of the six-month old animal were discovered in its field near Sittingborne, Kent the next day by its owner who is in his eighties.
After the incident, around 3,000 homes were plunged into darkness as the criminals took stole the copper cabling cutting the electricity supply.
Burnt to death: Callous copper cable thieves cut down a pylon leaving live wires exposed before using a six month old foal as a 'tester' to check if electricity was still moving through the line (file picture)
One resident told the Daily Telegraph : 'Almost all of us had no electricity on the night in question, but when we heard about the foal being burned alive everyone was horrified.
'Most of us believe the people responsible used the foal to test whether the wires were still live - either by putting it on the cable or tempting it over with food.'
The owner of the field where the foal was found said the animal was horrifically burnt.
She said the owner was left heartbroken after having to remove the remains of his horse.
The reported that Nick Rogers, head of health and safety at UK Power Networks, said: 'The criminals whose reckless actions led to this foal’s death had no regard for public safety.
'These are not victimless crimes and apart from the disruption caused by the power cut, this was a really distressing incident for the owners of the foal and our staff.'
Cable thefts are on the rise in recent years due to the rising value of copper and other metals.
Cable thefts are on the rise in recent years due to the rising value of copper and other metals. Nick Rogers, head of health and safety at UK Power Networks, said: 'These are not victimless crimes'
A village was plunged into darkness last week after thieves stole more than 1,000 metres of overhead cabling, cutting off the electricity.
More than 300 residents of Newton on Trent, Lincolnshire, were the latest victims of a crime wave spurred by an unprecedented boom in the value of metals.
The lights went out just before the beginning of Strictly Come Dancing on Friday, and power was not restored to homes and businesses in the village until around 3.45 the next morning.
The thieves had climbed 18 metres before using cutting equipment on the cable before stealing it.
British Transport Police said that cable thefts have cost £43million in the past three years.
Last week thousands of commuters were left stranded in London after a massive cable theft sparked a track fire.