Recently an inspector told me that large staples be used to secure flexible metal conduit (1/2 and 3/4 inch). I normally use either one hole straps or minerallacs with a screw. My master electrician said not to use the staples as they are a mark of sloppy work. It's a bit of a touchy subject between us, so I wanted to hear from others what makes a staple inappropriate. I can see that a screw holds a lot faster than the staples' two nails would... Perhaps someone with more experience can share their insight.
Welcome to the Forum !
I'm partial to Sturgeon Bay staples and have used them most of my career. I just went
their buyer's guide to see what the various staples they make are actually listed for. Flexible metal conduit is not shown as supported by their staples. AC, MC, NM, UF, SEU, SER, EMT, Pex, Coax, Category wire, Copper pipe, all YES, but no FMC.
If your company supplies you with a different manufacturers line of staples, go to their web site and look up the specs on the staple that your inspector would have you use. See if, in fact, the product is tested to secure FMC. If it is not, print out a copy of the specs to share with the inspector, or put a copy of the file on your phone for the same purpose.
In my opinion, FMC is kind of an odd size, and not a lot of it is installed nowadays. The staple or fastener should be intended for the specific measurements of half or three-quarter inch flex.
