wire under loft floor

[MarkAndDebbie]

I've been focused on getting the cabin dry - framing and roof. But before I go too far I want to make sure I don't forget something that is easy now and hard later.

I was going to run wire in the loft "beam" (2x12 | 2x6 | 2x12) to put a light in the middle of the bedroom. But once I put the loft flooring on (2x6 T&g) that will be hard. I wasn't thinking about doing the wiring yet, but I thought I might run just that for right now.

Will I need to "staple" it with those plastic wire holders?

Also, I was not sure the best way to get the wire into the chase. I other words - how do I go from the wall to that space in the "beam" above the 2x6 - where do I drill?

Thanks!

[Redoverfarm]

I've been focused on getting the cabin dry - framing and roof. But before I go too far I want to make sure I don't forget something that is easy now and hard later.

I was going to run wire in the loft "beam" (2x12 | 2x6 | 2x12) to put a light in the middle of the bedroom. But once I put the loft flooring on (2x6 T&g) that will be hard. I wasn't thinking about doing the wiring yet, but I thought I might run just that for right now.

The simplest way that I have found is to either route out a 1/2" wide chase in the top (where the T&G goes) of the beam.  I assume you are giving the makeup of the beam with your 2X's above.  There is no need to lessen the center 2X by that much.  If you don't want to route or cut it out then go with a 2X10 (held flush to the bottom) in the center which will give you plenty of room to run a 12/2 or 12/3 wire to go to a light or light/fan combo. I routed the top of my 4X8 to 3/4" width and depth to accept 12/3 in a 3 way configuration without any problem

Will I need to "staple" it with those plastic wire holders?

Just a few staples to hold the wire down in the chase "flat". Just be careful when to attach the T&G that you do not penetrate the wire.  With that demension of lumber you will have no problem finding a nailing surface on either side of the chase. You could do a continuity test on the wire as you progress to make sure of that.

Also, I was not sure the best way to get the wire into the chase. I other words - how do I go from the wall to that space in the "beam" above the 2x6 - where do I drill?

I am not clear on how you are going to support the beams? Ledger?  If the beam make-up protrudes into the wall cavity then just notch out the top and one side of the 2X to gain access to the chase if it goes completely against the wall or enter from the end if it just sits on the let-in ledger.  Just remember to go through a switch box before putting the wire into the chase .  As far as getting the wire to the ceiling just drill with a ship auger from your chase to the bottom of the beam.  It doesn't have to be really large as the diameter of the wire is not that great.  You could also in the assembly stage route out 1/2 of the wires diameter in each of the outer 2X and the inner 2X for your drop to the ceiling.  



Thanks!

[NM_Shooter]

I might need a little more detail... is the loft beam exposed, or is it covered with a T&G ceiling?  Are you wanting to suspend the light fixture directly from the bottom of the beam?

If the beam is covered, don't come through the beam.  Attach a ceiling box to the side of the beam and be done with it.  You'll never notice the slight offset once the ceiling and light fixture is done. 

If you need more strength to support your fixture, (or you want to attach your ceiling box to the bottom of something rather than the side) nail two 2X6 scabs onto the side of the beam, leaving a small space between the scabs to route the wire through.  You probably know this already, but you can get either a full depth ceiling box or a smaller 1/2" depth surface box. 

Yes... do staple the wire well away from the surface of the T&G.  It is very easy to puncture the wire when putting the T&G on if the wire is not secured away from the nailing surface.  I believe that you need to fasten the wire within 6" of the box.   (check your code). 

I'm guessing you were wondering about drilling the beam, and not the top plate to route the wire?   

[Redoverfarm]

Frank from the discription of how Mark is going to try to create the wire chase you can only assume that he wants the wire hidden rather than run it on the outside of the beam.  It's hard to look into another persons mind but that is what I gathered from the post.  I think if he would drill a wire chase hole verticle from the horizontal chase at the seam of the inner and outer 2X's there would not be much comprimised regarding the strength of the beam.

[Don_P]

I think if he would drill a wire chase hole verticle from the horizontal chase at the seam of the inner and outer 2X's there would not be much comprimised regarding the strength of the beam.

There is a definite strength loss, the net section of the hole (one reason to keep it small). The hole is generally right in the middle of span, worst place. This is all part of designing the beam's dimensions with this section gone. If an inspector is tight and doesn't see that hole on the plans and a light dangling from the beam in real life he can have you get an engineer out to show that the beam is still up to snuff... but I may have admitted too much already   
That is the way I do exposed beams most times, or a bloc between beams that the light hangs from. But, check the beam with the hole in mind.

[MountainDon]

I see Don_P addressed this as well....

It seems to me the object here is to hide the wiring. The undersized sandwich beam component is what makes me think that. I'm assuming that the "channel" left was to be at the top with the bottom edges of the built up beam flush. If I was doing that I would place the wiring in metallic conduit so there was no chance of a nail contacting the wiring. THHN inside EMT conduit, unless the channel or chase was at least 1.5 to 2 inches deep. Wiring like NM or Romex should definitly de stapled down in the bottom of the channel/chase.

However, if that center 2x is actually meant to carry a part of the load there's a problem with drilling a hole through it to get the wiring down to the light fixture. There should be no holes or notching in the central section of a beam or joist, IIRC.

It may be simpler to simply run wiring in conduit, painting the conduit a complementary color. After all conduit does happen.

If there is an future electrical inspection involved, you may want to ask now, before forging ahead with hiding a wire in the built up beam. If you do go ahead and embed the wiring be sure to leave plenty of wire length at each end, especially the end that goes to the wall as you can not have hidden splices behind the wall or in the floor. Splices need to be in an accessible box.

[PEG688]

  I think he wants to hide the wire as it travels out to the center on top of the beam.

   If so I'd rout a "U" shaped groove on top , down the center of the top of the beam. To keep nails from being driven into it one could be careful when nailing the T&G to the beam or a shallower "outer" U could be routed to house a 1/4" steel plate say 1 1/2" wide that would lay over / above the wire that is in the deeper and narrower U shaped groove.

Or we all could have it wrong about what Mark is asking       

[PEG688]

I've been focused on getting the cabin dry - framing and roof. But before I go too far I want to make sure I don't forget something that is easy now and hard later.

I was going to run wire in the loft "beam" (2x12 | 2x6 | 2x12) to put a light in the middle of the bedroom. But once I put the loft flooring on (2x6 T&g) that will be hard. I wasn't thinking about doing the wiring yet, but I thought I might run just that for right now.

Will I need to "staple" it with those plastic wire holders?

Also, I was not sure the best way to get the wire into the chase. I other words - how do I go from the wall to that space in the "beam" above the 2x6 - where do I drill?

  Humm, so your beam is a built up style beam, will the 2x6 be held at the top or bottom of the 2x12?  Now this may not work , or I may not be able to write exactly / understandably what you could do. But If you held the 2x6 1" short of the end you could route the wire up into the space the 2x6 creates and out to the center of the room / beam.

  Seems pretty easy to me , if thats what you're asking about.



   

[Redoverfarm]

Frank from the discription of how Mark is going to try to create the wire chase you can only assume that he wants the wire hidden rather than run it on the outside of the beam.  It's hard to look into another persons mind but that is what I gathered from the post.  I think if he would drill a wire chase hole verticle from the horizontal chase at the seam of the inner and outer 2X's there would not be much comprimised regarding the strength of the beam.

Don_P I knew there would be some but keeping the diam of the hole as small as possible and to somewhat "split the difference" between the two beams of that diameter (1/4" to each)would work better than just center drilling through that small of a filler(2X6) which would in essence be far worse.  Why we are on the topic what would the engineer say concerning the less than equal demensions of the center 2X in comparison to the outer ones?  IMO if the beam failure would occur it is more likely to occur from the less than standard lumber that one can get now days.

For the lack of sufficent headroom in my cabin I elected to mount the fixture to the ceiling rather than the bottom of the beam.  I removed approximately 3/8" - 1/2" square hole next to the ceiling to run the wires out to the outside of the beam from the chase.  If this would be more acceptable to Mark then he could fabricate a wire mold out of channeled 3/4 stock (stained and finished to match the beams)  to take it to the bottom of the beam and box.

MountainDon I really don't see the concern for attaching the T&G near the chase.  I personally used screws to attachment my T&G so there is less a chance of severing the wire.  One could also drill pilot holes for this one beam in the T&G to insure that the screw did not stray from their path as nails often do. In essence you have at least 1-1/2" on each side for attachment. Yes it is a little slower in that area but not that much to use a few screws.

PEG688 I had thought the same way as you regarding the entrance of the wire from the wall cavitity but without knowing how he is going to install the beam.  Like others until Mark replies I guess we will be "second guessing him". 

[Don_P]

John, I took us off track, just wanted to point out that a vertical hole can be an issue. I doubt the 2x6 here is anything more than a spacer... but I don't know.

You asked how an engineer would look at a beam built up of different dimensions. I'm not sure on this one if the 2x6 would be counted. I've been building a model timber bent for a horse barn using dimensional sizes of lumber. I've been making build ups of 2-2x8's sandwiching a 2x10, flush on top with a decorative step in the bottom. I've been sizing the overall beam by adding the sum of the section modulus of each member. This is slightly conservative but doesn't hurt anything. I'm uniformly bearing on all three plies up top, there's the difference, the fasteners aren't trying to transfer force. If the connections are thought through this could be sized similarly.

[MarkAndDebbie]

Sorry, I seemed to have confused people up with my "beam". I was hoping to convey that it wasn't really a beam with the quotes.

These are really the floor joists in John's plans for the loft. It is two 2x12s with a 2x6 spacer. Here is a visual from an earlier post.



and from above



So I don't really need to route a chase - there's a big one by the difference in size (2x6 to 2x12).

I don't think I'll hit the wire if it's in the bottom of the case with a nail because it would be > 5" away.

These joists will be exposed.

I'm guessing you were wondering about drilling the beam, and not the top plate to route the wire?

No. I figured I could drill the 2x6 in the middle because it's not really carrying the load (though I am gluing it to reduce deflection). It's sitting on a let-in ledger - so not exactly the top plate. The 2x6 doesn't sit on the ledger or a jack (the stud is in the middle - in the way) - I'm just gluing/bolting all 3 together.

Humm, so your beam is a built up style beam, will the 2x6 be held at the top or bottom of the 2x12?  Now this may not work , or I may not be able to write exactly / understandably what you could do. But If you held the 2x6 1" short of the end you could route the wire up into the space the 2x6 creates and out to the center of the room / beam.

Yes, PEG has it. But since I have the stud in the middle (maybe I should change that), the wire would have to run up the wall, then out into the room, then into the gap between the stud and 2x6. I could trim this, or could notch the stud, or run the wire up beside the 2x12 - drill the 2x12 at an angle into the chase.

Thanks everyone.

[PEG688]

Yes, PEG has it. But since I have the stud in the middle (maybe I should change that), the wire would have to run up the wall, then out into the room, then into the gap between the stud and 2x6. I could trim this, or could notch the stud, or run the wire up beside the 2x12 - drill the 2x12 at an angle into the chase.

I'd rout a groove  about 5/8" deep  in the back ( side against the stud) of the 2x12 , rout it at a angle from the center of the 2x6 stud up into the open chase created between the 2x12's.

  You could later at wiring snake the romex wire thur that groove into the chase.

  You'll be covering that space at the bottom I'd assume so the wire wouldn't be seen. If your not planning to fill the space between on the lower side you could snake the wire thru the groove , attach it to a 2x ripping with wire staples then install the 1 1/2" x 1 1/2" ripping at the top of the beam , or find a way to hold the ripping down say 2 inches with say 16 d nails tapped in on either end to hold onto and also space the ripping down into the chase then nail it in place thru the side / thru the 2 x12's.

     But you can figure that out , the groove in the side of the 2x12 is the way to get the wire where you want it.   







   

[Redoverfarm]

PEG sounds like a plan.  I don't think I would wait until later to try to get the wire snaked through.  Just decide on 2 or 3 wire w/ground and put it into place and run ample amount to the location that you will pick up the switch.  It is easier to see what you are doing before the T&G.

[PEG688]

PEG sounds like a plan.  I don't think I would wait until later to try to get the wire snaked through.  Just decide on 2 or 3 wire w/ground and put it into place and run ample amount to the location that you will pick up the switch.  It is easier to see what you are doing before the T&G.

My assumition is a long time before he's in the dry.

Maybe a pull wire or string , and my groove would, in theory, be clean and straight . Making it easy to slip the wire in at a later date.

   

[MarkAndDebbie]

Thanks. That's what I was looking for.

I hope to be dry (except windows and doors) by the end of the week. Looks like good weather. I've got the studs up and part of the sheathing on (more today). I've got a crew to help from the top-plate up and it looks like good weather.