When laying out raceway, always determine what kinds of tubing or conduit connectors you’ll use before selecting the boxes for that run. Why would you do this? Because you can’t use round boxes when those connectors require locknuts or bushings [314.2]. To work properly, they need a flat plane. Manufacturers publish tightening instructions; for example, “snug fingertight then give it a quarter twist with pliers.” The “old school” way is to (mis)use your
Tips for Selecting the Right Electrical Box
Determine what kinds of tubing or conduit connectors you’ll use before selecting the boxes for a run when laying out raceway.