Police say thieves behind copper wire thefts in Port Talbot are putting their own lives at risk.
This week a quantity of the metal was stolen from the Eagle Street telephone exchange in the town.
Earlier this month there was an attempt to take wiring from a power station in nearby Baglan.
Ch Insp Karl Eenmaa said as well as endangering themselves the thieves put others at risk by disrupting power and telephone supplies.
The theft at the telephone exchange occurred around 2030 BST on Tuesday.
Ch Insp Eenmaa said: "Cutting into any wiring, especially where the mains services are connected, is extremely dangerous.
"People who carry out this type of crime expose themselves and others to possible serious injury, or even worse."
South Wales Police are appealing to witnesses who saw anyone acting suspiciously near the telephone exchange on Tuesday evening to contact them.
Call the non emergency number 101 or Crimestoppers anonymously on 0800 555111.