It is in the code. I think it differs electric and gas.
I went to mostly GFI breakers as the outlets you get from the orange and blue stores are unreliable in my experience. Most of my house is on GFI. Now new code says AF-GFI for a lot of circuits, but I found them unreliable. Use only commercial grade outlets. Never the 98 cent crap and never the back-stab connections. I don't trust the new Waco connectors based on my years in Failure Analysis for a computer company. Took a two week class from AMP on interconnections, from die to substation transformers.
Never assume your contractor has a clue. A few do, many are completely clueless. A few more do know, but if not watched and questioned, will do it the cheap easy way instead of correctly.