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What is the smallest 3/4" EMT coupling to pass through drilled holes?

What is the smallest 3/4" EMT coupling to pass through drilled holes?


  #1  
Old 12-06-23, 09:45 AM
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What is the smallest 3/4" EMT coupling to pass through drilled holes?

I am running 3/4" EMT from a wall into the attic, through a double top plate.

At the wall, I have a 12"X8" cut out about 4' below the ceiling where I will be mounting a new three gang switch box.

In the attic above, I have only 14" of head room where the roof slopes to the eave.

I drilled a 1-1/4" diameter hole through the double top plate from the attic to the wall cavity below.

I can pass a 3/4" EMT conduit (with a 90 degree bend) through the hole to below, if I had 4' of attic space, I can bend an EMT conduit with a 4' and stick it through the hole and have it reach the cut out in the wall cavity below...but due to the limited head room, I can only insert a piece with 14" after the 90 bend. Not going to be able to reach up that wall cut out to even touch that end to make the connection to the next vertical segment.

My next attempt is to insert a piece of EMT 18" or so at the cut out into the wall cavity from below, and once the first piece is in, I insert a second piece and connect using a set screw coupling, then a third piece, and I can feed that EMT up through the hole. I can then connect the attic piece with the 90 from above with a coupling. But with this coupling, I cannot lower the 90 back down so that the horizontal portion stays low (about 3" above the top plate) since an AC duct is in the way,

The EMT coupling WITHOUT the set screws can slide through the drilled hole but with the set screws sticking out requires a much larger hole. I am thinking even 1-1/2" may not clear it.

I wonder if there may be other couplings I can use for EMT connection that has a smaller diameter overall to clear a hole? Will compression couplings be smaller? But the lock nut looks quite thick all around.

Yes I am aware that I can just make another cut in the wall below the ceiling just to make this connection, but this is very thick (over 1-1/2" thick) old rock lath plaster and I want to prevent making another cut if at all possible.

Sorry for the long post, in summary, I am looking for a coupling for connecting 3/4" EMT conduits that will require the SMALLEST drilled hole diameter to be passed through.
 
  #2  
Old 12-06-23, 12:08 PM
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do you really need 3/4"? Maybe a headless set screw substitute on the coupling.
or, metal clad conduit?
 
  #3  
Old 12-06-23, 12:32 PM
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Why bothering with EMT inside a wall and protected area of attic? NM cable (Romex) is acceptable in such situations especially when not in new construction..
 
  #4  
Old 12-06-23, 01:07 PM
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Or run MC if you really want/need it to be in metal.
 
2john02458 voted this post useful.
  #5  
Old 12-06-23, 01:48 PM
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The existing wiring is EMT for the most part, with some MC cables to lighting fixtures. I am trying to stay with the same.

With five devices to switch (2 fans with lights, 2 wall scones, 1 cove light), and possibly there will be changes (debating changing cove light to a three way), I want to stay flexible with possible adding/deleting in the future.

Right now I am trying to minimize the number of conductors required. Using EMT allow me to skip the EGC, and I can also skip the neutral to the switch box since it is not needed now but can be pulled in the future. I counted 9 conductors and think 1/2" is too tight, 3/4" should work but I won't be able to add new conductors since 9 current carrying conductors are the max. May be I need to run two 1/2" EMTs instead.

In any case still want to know what coupling will require the least hole size to pass through for EMTs.
 
  #6  
Old 12-06-23, 03:04 PM
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I would think the smallest coupling is 3/4" EMT compression coupling.
 
  #7  
Old 12-06-23, 06:18 PM
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You can also use a set screw coupling and then after tightening the screws, you cut the heads off. You only get one shot at doing this as it will be impossible to remove the coupling.
 
 

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