You will find all sorts of ways to use them on a job site.
In this video, Rob shows you how to use them to secure the connection between extension cords and power tools - without tying the extension cords together (which isn't a great idea to begin with).
Then, with some degree of humour*, Rob shows you how a zip tie can even double in an emergency for a lanyard. That is, when you need to hang a power tool off your belt and don't have your usual secure connection.
Please read the disclaimer* below regarding Working At Heights and job site safety.
*DISCLAIMER: Provincial "Working At Heights" regulations contain CSA and other specifications for approved/allowed body belts, harnesses and lanyards. The use of zip ties or other non-approved methods to secure tools to belts, as shown is this video, may violate these regulations and equipment specifications when working above the ground. Canadian Contractor and its sponsors urge you to use CSA-approved, legal tool connections and lanyards. Stay safe, obey the law.