Central Networks has put up a reward for information on copper thieves in Gloucestershire after seven attacks in the last two months.
The thieves have been risking serious injury or death by climbing high voltage pylons to steal over 9km of Central Networks cable.
In Fromebridge the thieves stripped 7km of copper cabling leaving the remaining overhead line hanging dangerously from the tower.
They also brought down 400 meters of cabling running across Frampton Youth Football Club, causing 357 customers to experience an interruption in their power supply.
In Purlieu, Lydney 1400 meters of copper earth wire was taken from the top of dual circuit pylons.
Central Networks manager customer operations, Phil Wilson said: "This is a new one to us - we've had people using chainsaws to cut through wooden poles and breaking into substations but climbing high into the sky to take cabling with 33,000 volts going through it is just plain daft.
"Even if you ignore the fact that they're putting their own lives at risk, they're also causing inconvenience to thousands of customers, costing us money and producing dangerous working conditions for our engineers.
"We're working closely with the Police and Crimestoppers to ensure these criminals can be brought to justice, which is why we we've made the decision to increase the reward."
The police have appealed to the public to come forward with any useful information to help with apprehending the thieves and reported that they had made arrests regarding an incident in Fromebridge.
Stroud CID's DS Alex Casling said: "Thieves are risking their lives as well as disrupting the power supply to households in this area of the county.
"People rely on a sound electricity network and that right is being jeopardised by these offenders. For the good of everyone in Gloucestershire, please call us if you have any information.
"I also want the public to know that progress is being made thanks to our partnership with Central Networks. Three people have been arrested and bailed in relation to the theft of 7km of cable from a farm in Fromebridge in September."
