How thick is my top plate? Trying to drill through it.


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Old 05-20-20, 04:32 PM
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How thick is my top plate? Trying to drill through it.

I am trying to run electrical wire from my attic down to my breaker in my garage. I have 90' angle drill and I'm drilling up from the garage. I took off my dry wall and am drilling straight up through the top plate. I was under the impression the top plate is 2 inches thick. I am 3.5 inches in and still not through. I have not gone any further out of fear I am doing something wrong. Any advice on what to do or any idea on what is going on?
 
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Old 05-20-20, 04:35 PM
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Top plates on load bearing walls would be 3 inches thick.

you may have caught the rafter or joist after going through the top plate. Can you move about 2 inches away and try again? Do you have a stud finder or tap on the ceiling and listen for the change.
 
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Old 05-20-20, 04:36 PM
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Normally it would be 3" thick since it's a double top plate... thicker old lumber could be 4".
 
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Old 05-20-20, 06:16 PM
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Thank you two for the reply. Unfortunately this spot where I am drilling seems to be the only good spot. There is a wire already going there it on the right side, I guess the next thing to do would be to measure my hole and the cable and try to go into the attic and see if I just have a thicker top plate. It is just difficult because the attic is completely unfishable so I am walking on the side of 2x4s up there and it is a distance I only wanted to make again when it comes time to fish the wires through but I think that is my only option right now.

The breaker panel I have seems to be perfectly in-between two studs in my garage. I removed the square of drywall (a 3"x3" square) right in the middle of the two boards. The hole up is slightly to the left inside of that 3"x3" cutout. (I can try to take a picture of it when I get home from work tomorrow morning)

My house was built in 2002. Would that maybe be a time where they would have used 4" or was that a longer time ago?
 
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Old 05-20-20, 06:30 PM
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It should be 3". But for all we know you are drilling into the bottom of a rafter or into a piece of vertical blocking.

Take a coat hanger and put a slight 1/8" 90 degree bend on it and see if you can fish it next to the existing wire and feel the thickness of that hole.

Its rarely a good idea to go drilling into something when you dont know for sure if there is any wiring above it.
 
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Old 05-21-20, 03:21 AM
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Unless the house was built with sawmil lumber the 2xs would only be 1.5" thick [3" doubled] That said we ran a circuit at my son's house where for some unknown reason the top plate was three 2x4s thick. Sometimes you can tap at the top of the wall and get an idea of where the lumber is.
 
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Old 06-01-20, 04:41 PM
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Thank you guys for all the help. I went up to my attic and measured it and I was drilling right into a rafter. So like PCBoss suggested I moved over a little and popped right through. But I learned a lot of trouble shooting techniques from what you guys all said so thank you!
 
 

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