The ESB says one person has died and three people have been seriously injured while trying to steal highly-valuable copper cables from its live network around the country.
The State electricity company said it has cost €27m to repair lines after the theft of cable with a value of €2m-€3m in the past 24 months.
It is believed other agencies such as Eircom have spent thousands of euro in repairing their own lines after thefts.
The ESB has appealed to the public to exercise caution at all times if they come across cable that has been left on the ground, especially in rural or isolated areas.
Many of the thefts have taken place in the midland region over the past ten weeks.
Incidents have been widespread in Offaly, Laois and Westmeath.
Gardaí say an international crime gang is behind many of the thefts.