The phrase "wiring for dummies" is simply a way of referring to wiring instructions for those with little or no experience with or knowledge of wiring. Although "for dummies" has become a catchphrase, it evolved from the "For Dummies" book series of do-it-yourself-themed instruction guides.
The "For Dummies" book series is a popular series of books published by Wiley and Sons. The first book in the series, "DOS for Dummies," was published in 1991. Since then, there have been more 1,600 "For Dummies" books written with more 200 million copies currently in circulation. Authors of "For Dummies" books vary from title to title.