Conduit through sill plate under joists?

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Old 01-12-15, 03:52 PM
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Conduit through sill plate under joists?

A while back I posted this thread about running conduit in my basement. I haven't made any progress!..LOL

I have 3 big I-beams I have to go around (actually under) to get from one side of the basement to the other. On top of these I-beams however is a 2x8, what I will call a sill plate that the floor joists sit on. Notice in these new pictures that the existing ceiling lines up exactly (or thereabouts) with the sill plates.. If I could drill straight holes through these 2x8 I would not have to bend any conduit at all (otherwise I am looking at 12 90degree bends - 3 beams x 4 bends). Maybe you can make out the sill plates above the I-beams in these pictures (they're all painted the same color)





Is this a bad idea? Is it allowed? Will it affect the structure of the plate? The only catch is that in one section the joists run perpendicular to the plate, so I don't know what I would actually hang the conduit from in that section. Also, if it is possible/allowed/ok how do I drill a hole straight through this 2x8??

Cheers
Dukester
 
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Old 01-12-15, 04:26 PM
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Bends

If I could drill straight holes through these 2x8 I would not have to bend any conduit at all (otherwise I am looking at 12 90degree bends - 3 beams x 4 bends)
You are only allowed a maximum of 360 degrees worth of bends in a conduit run between access points.
 

Last edited by pcboss; 01-12-15 at 05:20 PM. Reason: clarity
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Old 01-12-15, 04:40 PM
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And any bend around that beam would have to start probably 3' back from it. I haven't done the calculations on it, but as Ken said, you won't use 90 degree turns. Drilling horizontally through the 2x8's may prove to be a bear, but unless it is supporting anything at that point, it shouldn't make a difference. I would run the conduit up and over the beam using 45 degree offset bends. Not sure what you would have to do with your ceiling, however.
 
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Old 01-12-15, 05:13 PM
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So there would have to be a junction box after each set of 90's? Which would be ok, because I'd need to come off of that run for lights there anyway.
 
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Old 01-12-15, 05:17 PM
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Up & over and then back down would require almost as much bending as down & under and then holes in the joists.
 
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Old 01-12-15, 05:23 PM
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That plate gives the joists a place to attach to. The joists cannot nail to the steel beam. I would offset over the beam.
 
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Old 01-12-15, 06:04 PM
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You could also 90 down, use back to back pull elbows or LB's, then 90 back up.
 
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Old 01-13-15, 06:08 AM
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Have you considered a different route entirely, like along the outside of the building, or where the side wall of the room meets the ceiling, and build a small bulkhead out around it?

Otherwise I'd make an effort to kick over the beam.
 
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Old 01-13-15, 06:14 AM
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Yes, but the beams span the width of the house. In any case there would be multiple 90's going around the interior periphery of the house, if not more than going around the beams (There are interior block walls that intersect the exterior walls)
 
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Old 01-13-15, 06:21 AM
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What are you attaching the conduit to out in the room area? The bottom of the joists?
 
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Old 01-13-15, 06:40 AM
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Yes, it would be mounted on the sheetrocked ceiling but screwed into the joists.
 
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Old 01-13-15, 06:47 AM
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Drilling

What size hole would you need to horizontal drill through the 2x8?

A bit with a flexible shank should work if you can find the right size.
 
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Old 01-13-15, 06:52 AM
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A small offset over the sill and back down will solve the issue.
 
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