Need help on the details of mounting an octagon box that will be embedded in a brick wall. It's new construction, a block foundation wall with a brick face. The block wall is up and I need to locate a box for a light fixture that will be on the wall beside the garage door. My thought is to drill a hole in the block where I want the box to be, rough in a length of nm from the switchbox through the block, clamp the nm through the side of the box and let it hang, leaving it for the masons to locate so that it's easier for them. Does this sound right? If so, how is the box captured by the brick? Are there boxes with brackets for this purpose? Or should I attach the box to the block using screws and anchors and let the masons work around it? Most of my work has been in industry and old residential work and I have not come across this until now.
I've normally roughed in a masonry box like Fred described, but 95% of my experience is commercial and industrial applications. Every box that I've put in a block or brick wall was held in place by the morter. I have put 4/0 (octagonal) boxes in masonry walls before, and they work fine. If you stub out a wire like Jon (who sounds as if he has much more residential experience than I do) says above, I would go a step further, and tell the brick foreman exactly where you want the box to be located in the wall. Remember, if it is wrong, that brick mason will be long gone to the next job, and they'll be asking you why the box is in the wrong spot. Good Luck. HMEL #688
The Watt Doctor Altura Cogen Channelview, TX
#6297 - 01/01/0211:16 PMRe: new const.-box in brick
I'll have to contact the bricklayers. I'd like to know if the brick is run up against the block or if they leave a space between the two, say a 1/4" or so. If there is normally a gap I'd like to run the box to box romex (between the two lights) between the brick and the block. I think it would make for a cleaner job. I'd like to work for a new construction contractor for a week or so to answer some of my many questions about the small details. Don
#6298 - 01/06/0207:32 PMRe: new const.-box in brick
Can you run NM through block like that? Or even between block and brick like that? I always thought that it had to be run through a piece of stubbed conduit so that as the brick moves with temperature changes, the sheathing on the NM is not rubbed off and possibly eventually the insulation on the wire itself rubbed off.
#6299 - 01/08/0211:08 AMRe: new const.-box in brick
>Can you run NM through block like that? Or >even between block and brick like that? I >always thought that it had to be run >through a piece of stubbed conduit so that >as the brick moves with temperature >changes, the sheathing on the NM is not >rubbed off and possibly eventually the >insulation on the wire itself rubbed off.
The code says it has to be protected from damage. I don't see how it can be damaged through a 3/4" hole in block or running in the space (1/2" min) between the brick and block. I see no other way to rough the circuit in before the masons do their thing. The boxes are hanging on the romex, the romex between the boxes that will be behind the brick is clamped to the block and the masons will locate the boxes as they lay the brick. Is there a better way to do it? Don
#6300 - 01/08/0211:11 AMRe: new const.-box in brick
>Around here if you are going to use NM >cable, we simply leave the wire stubed out >with a single gang plastic box hanging from >the end of it. Then the mason locates as >needed.
That implies you might use another cable or bx. How would it differ? Don
#6301 - 01/08/0203:41 PMRe: new const.-box in brick
I am thinking in terms of two dissimilar materials with a NM wire sandwiched between. As the block and brick expand with temperature changes, the NM is going to be subject to constant rubbing. I think that the wire should be run directly out of the back of the box through the block with a piece of rigid or EMT. It will protect the wire and get it into the inside of the building where it can then be run to the next light. Making it both easily servicable in the future and also giving it a little more protection from natural occurences. This setup would also allow the installer to place the box where they want it and not just where it would end up.
#6302 - 01/08/0209:44 PMRe: new const.-box in brick
I wish that I could speak from experience but new construction is not my forte. However, I think it is important for appearance sake that the mason lays the box into a course of brick. Regarding friction, I think a gap of at least 1/2" keeps the cable free and clear of those forces. Don