I have to install 50 or so exterior lights on a commercial building. Wall is normal concrete block with stucco.
Fixtures are wall mount and call for 4" octagons. I'm going to cut the boxes into the outer block and drill a hole through to the inside, install 1/2" EMT out the back of the box, and go into the back of another box on inside wall. Some lights are on outside of "pilaster", so wall is two blocks thick, but should still work. This will work for the ones above the height of the ceiling grid inside. Others are below the ceiling grid height. On these I think I will still go straight thru, but notch the block on the inside so I can get a 90 in there and run vertical flush with the interior wall so strips/drywall can cover. Going up thru the block and then over into attic is not a good option because of roof construction I think after looking at the architectural drawings. Blocks will be solid poured after.
My real question is will the boxes be secure enough after the concrete is poured? Does this sound like the way to do it? Any other comments in general?
I'm primarily an Industrial contractor. But I have been doing some small commercial lately. Thanks for any input.
If these boxes are going to be cast in concrete as in a cell pour I am not sure how you would get them to move at all. There are enough irregularities in a regular box that would give a pretty good bite. I had an octagon that was cast in place and one ear had a rusted in place screw. I took the ring off the connector in back expecting that a few taps with a hammer would dislodge the box. I ended up having to use a piece of #3 rebar like a drift punch and beat the snot out of the inside of the box, all around to get the concrete to release it's grip. YMMV depending on the slump and how much they vibrate the pour. They usually pour cells here at a 5 or even 6. That is a McDonalds milk shake. There will probably be a little grout in the box through the small holes
#57299 - 10/10/0512:12 PMRe: Exterior lights on block/stucco wall
Most of the wall pack type fixtures I use do not require a box behind them at all. They can be fed with a GRC nipple or EMT through the wall but the easiest way is sealtite. Drill a hole all the way through and connect the sealtite to a box above the grid on the inside.
#57302 - 10/10/0507:46 PMRe: Exterior lights on block/stucco wall