Far North residents are being urged to be wary of fake power company staff trying to get access to their homes.
Lines company Top Energy issued the warning after reports that people had been knocking on doors in the Waipapa area claiming to be subcontractors installing or upgrading smart meters.
Residents' suspicions were aroused because the men had no uniforms or ID and arrived in unmarked vehicles.
Top Energy network manager David Worsfold said subcontractors working for power retail firms were currently upgrading meters around the Far North - but they arrived in signwritten vehicles, wore branded clothing and carried identification.
"They will also be able to articulate exactly what they are doing and why. More importantly, if you are due to have a smart meter upgrade, you will have received notification advising you of this from your retailer."
Power retailers had also been informed that impostors were trying to get into people's homes by posing as subcontractors, Mr Worsfold said.
"Always ask for identification, and if you are suspicious of anything, please ring the police."
A spokeswoman for Kerikeri police advised people to ask for ID before allowing anyone claiming to be from a power company into their home, especially if they weren't wearing a uniform and had an unmarked car.
Another strategy was to ask for their company's phone number, make them wait outside, and call their office to check they were genuine before allowing them in. If they could not produce ID or a genuine phone number they were impostors. If they then refused to leave it was time to call 111.
To make a complaint about fake power company workers call Kerikeri police on (09) 407 9211, Kaikohe on (09) 405 2960 and Kaitaia on (09) 408 6500.