running pvc conduit through cinder block

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Old 06-17-13, 07:24 AM
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running pvc conduit through cinder block

I am looking for advice on mounting two identical electrical boxes (see pics below) on the inside and outside of my basement with a short section of straight 3/4" PVC conduit connecting the two.

These two boxes will house the wiring for my low-voltage irrigation zone valves. Splices will be made in the box that will be inside the house.

Note that in the pictures I have 1/2" PVC connected...this will be replaced with 3/4" because I need to feed through two sets of zone wires and with 1/2" PVC it will be a tight fit.

I will rent a hammer drill and appropriately sized bit, however I have no experience drilling through cinderblock other than to mount something on a wall with holes no larger than 1/4".

I don't plan on gluing the PVC section connecting the two boxes, just fitting it into the threaded connectors. Both boxes will be mounted to their respective walls with screws. This way if I ever need to remove the boxes for whatever reason, the most I'll have to do is unscrew the four screws, remove any weatherseal material and pop the boxes off.

I've been told that I should core drill and sleeve the conduit but is this necessary 8 inches above ground level? I'd don't even know what's involved in sleeving.

The hole for that I need to drill we be no less than 1 and 1/8" to account for the threaded fittings that screw into the backs of each box. I assume I should start by drilling a small pilot hole from the inside of the house. Then drill the larger hole from the outside.

Last but not least...will applying silicone around the box (inside and outside the house) be sufficient to weather seal it?







 
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Old 06-17-13, 08:10 AM
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Yeah this post looks familiar lol. Silicone is fine, just use some "great stuff" to fill any gaps from the outside.. Good luck, let me know if you need something better
 
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Old 06-17-13, 03:35 PM
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I do a lot of installations in block and masonry. In your application I would drill a 1/4" pilot hole first. Then a hole slightly larger than the PVC and then drill a larger hole right at the box for the connector....or use a star bit and hammer to enlarge the hole for the connector.

Silicone is fine for a sealant at the outside box.
 
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Old 06-18-13, 06:37 AM
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Can I purchase a 1/4" pilot drill bit long enough to go through cinderblock?

Is core drilling overkill for a hole slightly larger than 1 and 1/8"? The place I rent from wants around $80 for a 4 hour rental of a core drill.

Either way, I think I'll practice on an extra cinderblock I have laying around to make sure I get the result I want.
 
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Old 06-18-13, 06:52 AM
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I don't think you need a core drill for masonry block, it's very soft stuff. If you are near a Harbor Freight, you can buy a hammer drill and set of 12" bits for less than you will pay for a core drill rental. Not top of the line tools but fine for your usage.
 
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Old 06-18-13, 08:12 AM
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Are you talking about the SDS rotary hammer for $90?
 
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Old 06-18-13, 08:16 AM
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A rotary hammer drill will work fine. I use my Milwaukee 18v 1/2" hammer/drill gun for most holes in cinder block. The depot has inexpensive masonry bits.


Just looking at Harbor
5 Piece 12" SDS Masonry Bit Set
10 Amp 3-in-1 1-1/8" Variable Speed SDS Rotary Hammer
 
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Old 06-18-13, 10:54 AM
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Is that drill capable of making holes in masonry up to 1.25"?
 
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Old 06-18-13, 11:07 AM
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In block...no problem. As was said...much softer than solid concrete. No big stones in it.
 
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Old 06-18-13, 01:18 PM
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I have an 18V Dewalt Drill/Driver that has hammer drill mode. I've never used this for anything larger than 1/4" holes. Will this work for me? Do they make bits larger than 1" that actually fit the 1/2" chuck? I'm skeptical for some reason.
 
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Old 06-18-13, 01:52 PM
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I have an 1-1/4" Bosch bit that fits my Milwaukee. I drill up in steps.
 
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