IDEAL is not the only company that makes twist on wire connectors, but their WIRE-NUT brand is so well known it has become synonymous with the product, much in the way facial tissue is referred to as Kleenex—even when it's not that brand. It never would have occurred to me to ask how twist wire connectors are made. Fortunately I didn't have to, because during a recent tour of the Factories where IDEAL and SK make tools, I was also shown where WIRE-NUT connectors are made.
Twist on wire connectors are said to have been invented in 1914 by an electrician in Canada, who was looking for an alternative to the then common method of joining wires with solder and tape. IDEAL began producing twist on wire connectors after purchasing a patent from a Dutch company in 1929 and created the WIRE-NUT brand in 1946. The company continues to produce WIRE-NUT connectors plus a slew of other connectors including push-in connectors, terminal strips, and terminal and crimp connectors. Considering the source of IDEAL's original patent, it's ironic that twist on wire connectors are not popular in Europe, where screw connectors have long been the norm.
Click the slideshow on the left to see what I saw during my tour of the factory in the Sycamore, Illinois factory where twist and push-in connectors are made. Be sure to check out the captions because they explain what's going on and contain links to videos that show things that couldn't be captured in photos.