Thieves stole 35 reels of electrical cable and various other items after breaking into a building site.
Police are appealing for witnesses after the break-in at a building site in Christopher Close, Desborough, sometime overnight between Monday, July 27, and Tuesday, July 28.
As well as the reels of cable, a generator, power leads, a power adaptor and a bag of tools were taken.
Witnesses, or anyone else who is offered similar items for sale in suspicious circumstances, can call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.