Four North Island power companies will mark their electrical infrastructure with microscopic "nanotags" in a bid to reduce copper theft.
Northpower, Counties Power, WEL Networks and Powerco will take part in a six-month trial of the nanotagging technology that is being run in association with police and Crimestoppers.
The trial will involve attaching nanotags to metal components that are at risk of being stolen.
The nanotags, supplied by Timaru-based AVI Solutions, are invisible to the naked eye but contain identifying codes that can be read by handheld microscopes.
Crimestoppers chief executive Jude Mannion said AVI was working with the Scrap Metal Recycling Association to supply scrap-metal dealers with equipment to read the nanotags.
If anyone attempted to sell a tagged component, the dealer would immediately know it was stolen and the owner could be identified, she said.
Powerco acting electricity operations manager Phil Marsh said his company's primary concern was that copper thieves were putting themselves and the public at risk.
Copper thieves often target ground wires that are designed to protect lines and transformers.
"These thefts remove parts of the network designed to protect people and property and our concern is one day one of these thefts could lead to an electrocution," Marsh said.
In Northpower's annual report, network general manager Graham Dawson said it cost the company between $500 and $1000 to repair the damage and replace copper each time there was a theft.
Mannion said a similar nanotagging trial in Australia had reduced metal theft by up to 70 per cent in some cases.