Now, no need to scare the DIYs that badly, you're not gonna get much arc blast out of a residential service, especially not where the DIYs are working and the net result of the arc fault it a scorched piece of #12 and a tripped breaker. Showing them how their house burned down because they did something stupid, THAT would be more responsible of us!
This stuff isn't rocket science, the basics of residential electric are easy enough for anyone to understand and do properly. Sure, it gets compliated in some of the details, but 99.9% of DIY homeowners aren't going to be doing that. And 100% of them should be getting it inspected from their AHJ to make sure they're not going to burn their house down, that's the real problem- not so much that they're doing a few random things wrong, but that they don't fix their mistakes.
And let's face it, a lot of DIY mistakes aren't exactly huge satefy hazards. Only leaving 4" of wire at the box vice 6", for example. Or routing romex directly to a water heater or garbage disposal without conduit. Or tapping a light off the 20A GFCI kitchen circuit. Yeah, it's wrong and poses some sort of risk, and exactly the sort of mistake someone not intimately familiar with the code would make, but it's not exactly a smoking short circuit. If a DIY asks me a question, I'm going to tell him how to do it right, not tell him to hire a pro. (Well, unless he's trying to replace his panel or wire up a pool, or something like that.)
