Membrane Penetrations- how to avoid firestopping them Part 2

When you have an electrical box in a fire rated wall you have a hole in one side of a fire rated wall but not the other. The code allows you to have that hole and leave it unprotected PROVIDED that you follow certain rules.  

Once upon a time the National Electrical Code (NEC) had a little line that said you cant have a gap around the box that exceeds 1/8”. The problem is that often times its not the electrician making the hole. It’s the drywall contractor. That means you have to expect the drywall contractor to know the NEC??  That seems silly. 

But GUESS WHAT?!?! Some brilliant person decided that the NEC and the IBC should say the same thing, so NOW you can hold the drywall contractor accountable for keeping that gap to 1/8” or less because its in BOTH codes.  

So what happens if the gap is more than 1/8”?  Well, that is simple, you cant expect the fire rated wall to perform as expected. Its that simple.  

So what’s the fix?  If you fill the gap with drywall mud it’s a fast easy fix, but if you put that fast easy fix on a fire test furnace, you would not like the results.  The solution people often lean on is to just firestop the gap. Then the question becomes how big a gap can you have?  Or a better question should be , can you do that?   

The truth is firestop is often called on to fix an array of construction defects. That means you would need an Engineer Judgement from the firestop manufacturer you are using.  

I would like to encourage you to build this right so you can avoid needing to firestop it in the first place.   

What do you do on your projects to avoid these problems?