Scrap metal merchants say theft of metal is always more common when prices go up but measures are in place to make stolen material hard to sell.
Intruders broke into Trustpower's windfarm in the Tararua ranges on Monday in an apparent attempt to steal copper wire.
Scrap Metal Recycling Association Korina Munro president says as soon as a theft occurs, messages go out to members in the region where it happened to be on alert.
The organisation has procedures in place for people to report stolen metals on its website as well as to the police, she says, and this process has reduced the incidence of people accidentally buying stolen scrap metal.
Police say metal thefts have always been a problem.
The cash price of copper and lead on international markets has more than quadrupled in 10 years, while zinc has doubled and tin has tripled.