Receptacle in 3 hour rated wall

[woodduder]

We are being asked to install receptacles into a 3 hour rated wall. From what I have found it cannot be done. It is a UL U914 assembly (concrete block with 7/8" hat channel & drywall on one side). We would have to chip into the block cell to recess the box enough to fit and be flush with the hat channel. Electrical boxes are rated 2 hours max. Is there a way to install these outlets in this wall?

 

[Dennis Alwon]

If the box is 2 hour rated isn't there block on the opposite side. Surely that would count as an hour, No?

Where is North Star when we need him?

 

[Smart $]

If the box is 2 hour rated isn't there block on the opposite side. Surely that would count as an hour, No?

A lot depends on the block wall design...

http://www.orco.com/tech_fire_rat.htm

I think the architect needs to change the hat track to at least 1-1/4" (1-1/2" preferred, to allow for mud ring flange and screws), so shallow 4-sq's can be mounted directly to the block wall surface.