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Bringing Romex around a Post without Drilling

Started by jb9, August 30, 2017, 10:14:20 PM

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jb9

Hello,

I'm hoping there might be an electrician lurking on the group.  Anyhow, I am working on the electrical plan for my timber frame and I need to bring some romex from an exterior SIP wall around an 8x8 post and finally into an interior partition wall.  It does make sense to have the partition walls "break" on a bent which sometimes leaves the 2x wall "trapped" by timbers.  I have been hearing a lot of the expected advice from non timber framers which is, "Oh yeah, just drill a hole through that post!"  As you can imagine, I reject this solution.  Basically, the NEC code says wire has to be 1 1/4" from the face of a stud member to prevent it from being damaged by a screw.  Additionally, it states that a protection plate must be used if that depth cannot be achieved for the raceway/chase.  I do think I will have some kind of rustic baseboard trim so why not make a "post skirt" as I have seen them called.  I have attached a drawing showing my idea.  It is essentially a piece of 1" x 5 1/2" with a kerf cut in it so that I could slip a 1/16" steel nailing plate in to protect a shallow raceway.  In my mind, this seems like a stealth solution that would allow the romex to make it around the post inside the skirt and into the partition wall I have shown.  Does this look like a reasonable solution?

Any thoughts from electricians are welcome.

Thanks.



 

Don P

Why do you reject drilling through the post? The allowable knot size is larger than the hole diameter. Your plan would work. From the looks of the drawing a smurf tube in the sips around the corner and into the studwall would as well but I'm not sure I'm seeing the sips in the sketch correctly. Can you go underfloor and pop up in the studwall?

jb9

The OSB texture behind the partition wall is actually a continuation of the same SIP wall identified at the left of the rendering.  Sorry about that.  This detail is a small one and it only occurs at a couple places in my design so I don't mind doing a little extra finish work to avoid drilling the posts.  Also, I am running T&G ceiling/floor underneath so I don't have a floor cavity (sadly).

Roger Nair

If you are indeed trying to fold the wire tightly around the post in a confined chase, I think you are on the wrong track.  Wire should not be forced into tight turns around hard corners.  Wire should make changes in direction with a loose looping bend so the framing cannot apply force to the wire in case of frame movement.  Why can't you extend the wire through the framing surround and post?
An optimist believes this is the best of all possible worlds, the pessimist fears that the optimist is correct.--James Branch Cabell

PA_Walnut

Surface mounting with conduit would be an option.
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MbfVA

 smiley_eek_dropjaw
Sorry to be frank but...exposed conduit is ugly.

How about  coming up through the floor somehow, though I know you noted something about the subfloor posing a problem for that – how about running the wire tucked/hidden against a joist underneath?

When we build our house, I'm going to avoid all outer wall penetrations if possible.

We may need to use some floor receptacles, will design them in.

Same ick for roof penetrations, and for valleys & hips. They're often trouble over time and they raise costs.  OK, I do realize I'm imposing style limitations, but I'm counting on our River view to be the killer feature.   Saving our money for the rear wall that will face the river valley.

I appreciate this question being raised, because it has to be taken into account in the detailed design process.   Little things'll sweat you when they surprise you.
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Crusarius

Why do you not want to drill the post? are you concerned about structural strength? You could put roughly a 2.5" hole through that post and not effect the strength, this is if you do not take out the face of the post.

Den-Den

My electrical experience is mostly industrial but I have concerns about your concept.  Bending the wire around the corner like that will stress the insulation unless you notch the corner of the post AND are very careful with installation of the wire.  This looks like quite a bit of trouble with no benefit over drilling the post.
You may think that you can or may think you can't; either way, you are right.

Brad_bb

I did not want to drill timbers either.  I stick framed the walls because I wanted to be able to easily make changes.  I knew I would want to as we went along in the build- you want move a light receptacle or outlet for something you didn't foresee. 

If you're already committed, one suggestion instead of conduit is to use an armored conduit to whip around the timbers.  It can look better than regular conduit. 

To wire my timberframe, I created an electrical chase in the ceiling.  To do so, we apply the sheathing over the rafters (1x6 T&G).  Then I created a 2x chase on top of the T&G and the electricians ran all their conduit in that chase.  Then the roof sips when on the 2x grid closing the electrical chase.  I would not use this method with Romex though.  I did this to more easily wire all the lighting - a lot of pendant lighting and wips to track lighting and some cable lighting.  We dropped down runs into the 2x6 walls for the outlets, switches, and Lutron controls.  There were a couple places where we had the exact same problem you have and we decided to whip around the post with an armored conduit.  Mind you this was up where the post meets the ceiling or close to it.  I don't have a pic immediately available of that, sorry.


 
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

jb9

These are all helpful suggestions and ideas.  Glad to hear that the thread is helpful.  I do agree that a tight 90 degree bend inside that chase might put some stress on the insulation (noted).  I do think that a 90 degree RMT/EMT/conduit bend might work too.  I will keep drawing some of the ideas shown here and try to come up with a few safe, code compliant and aesthetically acceptable ideas.  I think notching the post corner is a good idea but I suppose that might be just as bad as drilling a hole through it.  My floor joists run perpendicular to the 2x conventionally framed wall shown in the rendering but I would have to probably cover the routed slot with a steel plate as well since my floor/ceiling decking is gonna get screwed to the floor joists.  I am assuming the armored conduit would contain unbundled but insulated conductors, yes?

One addendum is that I have been soliciting advice from some electricians as well.  When I compile those recommendations, I will post them here.  The electricians I have asked do feel that a protected chase behind a baseboard is code compliant.

Don P

Notching the post is considerably more detrimental than drilling through it. At the sizes I'm assuming we are talking about I doubt either is a problem. I assume you have notched and mortised timbers in the building and that joinery is larger than we are talking about. In a bending member it is more critical, do the math.

MbfVA

 let me ask a question: when one of OP referred to notching the post, would that not be disturbing the "face" of the post, bringing up the question of whether or not that's more weakening to the post than drilling a hole through the middle/avoiding the face?  my engineering training got cut short when I switched to accounting, but the advice to avoid cutting the face sounds logical in terms of the way wood structure works.   It also reminds me of what I learned long ago about notching floor joists.  If I recall correctly the limitation on a notch out of the board was more severe than on the size hole that could be drilled through from the side which was done in a way that didn't affect the load bearing surface.  Maybe my raising this will trigger more informed response & elaboration from our more knowledgeable members. 

The system just informed me that someone said exactly that.  don p was exactly the person I had in mind
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jb9

Here are a couple more drawings showing the staircase perspective with a few wall transition options from that side using RMT/EMT.  Coming from above might be work better aesthetically but it might be more complicated to wire...

Anyhow, here are some more renderings.



 



 

PA_Walnut

I've run wire like your 2nd drawing in old houses (my own) which I could get the right space to drill. Routed a channel in baseboard and ran behind it. Worked great.

The comment about surface mounted conduit is subjective. I have a rather cool/industrial office space and we can a lot of conduit, spiral ductwork, and rusty galvanized metal. Looks great, in my opinion, and of many others. All has to do with what you're into. Function should always exceed form.
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jb9

I would like to add one more additional bit of detail about the wiring.  I'm basically just trying to meet code and install a duplex receptacle on the 2x conventionally-framed wall as well as a switch.  So the wire I will be running is going to be 14-2 AWG so I am optimistic about a wire this small being able to fit into a baseboard chase should I decide to go that direction.  The conduit solution sounds like it would require a change from 14-2 NM (Non-Metallic Sheathed) to THHN (individually marked insulated conductors) and two junction boxes to support the conduit and transition from NM to THHN.  I appreciate MbfVA's encouragement to work through these details as a TF dwelling (house) is a much more complex endeavor than an outbuilding especially when inspections are required.  Thanks for following this thread and making suggestions too.  It is helpful.

Fallguy

I am an electrician the one thing you should do is talk to the local inspector. He is the one that is going to get the last say on whether your plan is going to pass. The tight bend radius on the inside and outside corners is going to be a major concern for him. If you can soften the corner of the post to increase the bend radius of the wire it may pass muster. I would get the inspectors input that way you will only have to do it once. Looking forward to seeing your solution.

MbfVA

Quote from: PA_Walnut on September 01, 2017, 05:24:01 AM

The comment about surface mounted conduit is subjective.
Function should always exceed form.

I'm not sure I totally agree regarding this situation (otherwise homes would be nothing but square boxes, an exaggeration but you get the idea...) , but I sure would like to convince Apple Computer of that.
pc_smiley
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jb9

Thanks Fallguy.  I think your suggestion is a good one.  I have already introduced myself to the electrical inspector so this will be a good question to follow up with.  We had a good conversation but he did say that inspectors have to be conscientious of the line between ensuring code-compliance and not dispensing design advice.  I always try to be careful with my language too to let them know I understand their position.  One thing I appreciate about a forum like this is that here folks have the opportunity to round up a set of possible solutions to a problem (solution A, solution B, solution C) and then the conversation with the inspector can unfold like this:

"I need to bring my wiring around this structural timber and I was considering A, B or C.  Would all of these solutions comply with the code?"

Anyhow, I did find something that says a 2 1/2" radius is about as tight as one ought to go with a wire bend.  The article said 2 1/2" is about the radius of a soda can.

Here's a drawing of how that bend might shake out with a 3/4" chase on the outside of an 8" x 8" post.



 

Don P

Draw the post with a 3/4" chamfer and move the coke can in?

PA_Walnut

Quote from: MbfVA on September 02, 2017, 05:10:10 PM
Quote from: PA_Walnut on September 01, 2017, 05:24:01 AM

The comment about surface mounted conduit is subjective.
Function should always exceed form.

I'm not sure I totally agree regarding this situation (otherwise homes would be nothing but square boxes, an exaggeration but you get the idea...) , but I sure would like to convince Apple Computer of that.
pc_smiley

I'm about as detail-oriented and visually motivated as you can be, but with the wisdom of age, I've increasingly been able to let things go due to a famous woodworker teaching me, "Better is the enemy of good.".

When I'm working on a project that I'm passionate about, I do my very best (often painstakingly) then move on/forward. On rockers I build, it's usually details I get tied-up on that no one else EVER notices or cares.

Bottom line is that, due to Life, Liberty and the Pursuit of Happiness (for now) we each can set our limits and tolerances and the OP will ultimately decide which option he likes best for his project, which I'm sure very few visitors will ever even notice.

I like to follow these threads in order to see the great thinking that goes on. They often exemplify necessity is the mother of all invention. BradBB's conduit if the roofing is a BRILLIANT option, which I've never considered. Beginning a timber frame of my own next month, it will certainly be on the table as an option! Thanks Brad!

As for Apple, don't get my started. I have used them professionally for basically the last 20 years. The dream died with Jobs.  >:(
I own my own small piece of the world on an 8 acre plot on the side of a mountain with walnut, hickory, ash and spruce.
LT40HD Wide 35HP Diesel
Peterson Dedicated Wide Slabber
Kubota M62 Tractor/Backhoe
WoodMizer KD250 Kiln
Northland 800 Kiln

Fallguy

The 3/4 chamfer that was mentioned by Don P.  may be the ticket to the bend radius problem. You well still need the nail plates also.

jb9

I just wanted to post an update to this thread.  I was finally able to speak with the AHJ (Authority Having Jurisdiction) regarding this detail.  I showed him my renderings and asked him his thoughts.  One thing I was aware of and wanted to share with the forum is that often times, the inspector is only charged with ensuring code compliance.  It's important to be mindful of this and not solicit design advice.  I definitely make sure to respect this reality and ask my questions accordingly. 

That being said, the inspector did feel that all the options would be viable as code-compliant (definitely needing nail-protection on the baseboard detail).  Additionally, RMT and EMT would be fine too as long as bushings were there to protect the sheathing from the sharp end of the conduit.  All in all, it was a great chance to learn from someone experienced who is committed to helping folks out who are building.

MbfVA

 in my experience with our local guys (1 woman, but yrs ago!), they can be extremely helpful if you approach them the right way.  Sounds like youv'e got one of those.
www.ordinary.com (really)

Wudman

Quote from: MbfVA on September 22, 2017, 04:51:42 PM
in my experience with our local guys (1 woman, but yrs ago!), they can be extremely helpful if you approach them the right way.  Sounds like youv'e got one of those.
Years ago I designed and blueprinted my home (I am a farmer / forester....not a building contractor).  I was serving as my own general contractor and needed to apply for the building permit.  I called the County Building Inspector and asked him what he needed to issue the permit.  I assembled that information.  On the morning that I went to the county office, the building inspector that I had talked to was not there.  His assistant looked through my plans and documentation prior to issuing the permit.  She said "it was one of the most complete set of documents that she had ever received.....and you are not a professional contractor".  I told her that I talked to the building inspector and asked him what he needed.  I phone call can save headaches.

Wudman
"You may tear down statues and burn buildings but you can't kill the spirit of patriots and when they've had enough this madness will end."
Charlie Daniels
July 4, 2020 (2 days before his death)

kantuckid

All codes aside-HA!, In our log house I used wooden "U" channels to hide wires a few places in my ceilings that all have 2x6 T&G. I made them on table saw from wood strips. Some wires are in routed channels in tops of log ceiling joists. I wouldn't drill that post if I had another way that suited me...
Kan=Kansas;tuck=Kentucky;kid=what I'm not

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