outlet on chimney cinderblock


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Old 08-09-14, 06:39 AM
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outlet on chimney cinderblock

Is it acceptable to mount a junction box/outlet on the exterior of a chimney on cinderblock with tapcons or cement anchors?

(indoors, in my basement)
 
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Old 08-09-14, 07:54 AM
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I see no reason why it wouldn't be acceptable.
 
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Old 08-09-14, 12:28 PM
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Need to find plan B.

Drilled into the block to attach an anchor to it and the "cinderblock" (not sure what the material is now). Is only like a 1" at best. My masonary bit went right thru... Once penetrated, I can feel the clay liner with my drill bit. So the block is likely hollow.

I don't supposed glueing a piece of board to the block with construction adhesive is adequate? If I was able to do that I would be able to affix the 1900 box to the board.

What do you suggest?
 
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Old 08-09-14, 12:54 PM
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I would have used plastic anchors and 1" screws. Tapcons would have been overkill IMO.
 
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Old 08-09-14, 01:10 PM
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I wasnt using tapcons, I was going to use a 1.25 plastic anchor and masonary screw. The hole I was drilling was for the plastic anchor. I don't think that will be very secure though.

Is the glued board not a good idea?
 
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Old 08-09-14, 01:27 PM
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A glued piece of plywood, at least 1/2" thick with PL 8X would work after good curing.
 
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Old 08-09-14, 01:50 PM
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Is there anything in the NEC about mounting junction boxes and the material used?

I mean I know I will have no problem glueing a backer board to the block and screwing a box to it.

But I want to know if its legit. Or if that would be considered sloppy.

Also the idea that wood would be touching an active chimney ... About 2' from the intended junction box is where my water heater flue enters the block into a clay liner.
 
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Old 08-09-14, 02:07 PM
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I don't know where on the chimney you are placing the receptacle, nor what you may or may not be covering the chimney block with, if anything. The code will require they be attached. No mention of method is made. Sloppy, probably depending on the location, and who will be seeing it. Your chimney block does not (should not) contain heat, as it is taken up via either terra cotta pipe (old) or metal piping. You must maintain 3" of clearance from combustible surfaces.
 
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Old 08-09-14, 06:23 PM
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Once penetrated, I can feel the clay liner with my drill bit. So the block is likely hollow.
I doubt what you felt was the clay liner and probably a partition in the block. I would have used that hole and however many more I needed for the plastic anchors.
 
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Old 08-09-14, 06:27 PM
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Plastic anchors with 1" screws are fine to mount a metal box to masonry.
 
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Old 08-10-14, 04:35 AM
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I doubt what you felt was the clay liner and probably a partition in the block. I would have used that hole and however many more I needed for the plastic anchors.
You are probably correct that it wasn't the liner. Where I was drilling was below where the entry point for the w/h vent is.

My bit went right thru that block like butter... if I were to stick a screwdriver in the hole that I drilled I likely could chip away at the brick easily. I am not sure that will be secure. I have 4 holes in the box I can drill for but they are rather close and I fear damaging the cinderblock.

The conduit is all supported well. There is about 4' between this box and another junction box. That junction box is securely fastened to a floor joist and I have 2 mini hanger holding the pipe to the joists between. I just need a little help holding the box flush with the cinderblock rather than full on supporting it from the cinderblock.
 
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Old 08-10-14, 06:50 AM
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Just use one or two screws. There is no need to use all four holes.
 
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Old 08-10-14, 07:22 AM
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Plastic anchors with 1" screws are fine to mount a metal box to masonry.

Is it acceptable to mount a junction box/outlet on the exterior of a chimney on cinderblock with tapcons or cement anchors?
yes

tapcons are great....2 is better then 1....4 is better then 2.............

i use flat head tapcons inside metal 4 in sq boxes because the hex heads cut into the wire insulation and short out sometimes.
 
 

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