Bangor Hydro Electric Company is again repairing a substation in its northern service territory after thieves stole copper wire from the facility for the second time in less than a week.

Company officials say crews finished repairing damage from the first theft on Friday, only to return Monday to discover that the newly-installed copper wire had also been stolen.

Bangor Hydro Safety Officer John Greaves says the company is working with the Sheriff's Department and the Maine State Police to find the thieves. Greaves says they're not only damaging Bangor Hydro equipment, they're putting employees -- and themselves -- at risk.

"I don't think the thieves understand that they could face injury or even death by cutting these wires," Greaves says in a statement. "Power lines and substations operate at voltages as high as 345,000 volts, which is 3,000 times that of the outlets in a home."

Company officials declined to name the specific substation targeted by the thieves, but they say they've increased surveillance at their substations, and are installing motion detectors and other equipment at an increasing number of them. They say stolen copper is very expensive to replace and repairs can result in customer outages.