Running Electrical Wire to Avoid Drilling
So sorry. I know this isn’t an electrical forum, but I value your opinions.
I cannot google correctly any code to get a good answer. Can wiring/Romex run in a non efficient manner (but otherwise attached correctly, etc) for the purpose of avoiding drilling structural post/beam and ridge beams?
Of course all corner framing is structural will be drilled and I’m not being ignorant of that point. I know that drilling 1/2-1″ holes centered is safe. However, my cathedral ceiling has a substantial 6 dimensional board center post. The addition created a double wall where the wiring is coming from.
My idea is that through the double wall, I would take the line from one outlet box then branch off into different directions to terminate at outlets on either side of the post, but separated by the post. At this point, I haven’t drilled the new two posts. So instead of one continuous line, it would be two lines (not connecting obviously.
Yes, the extra runs would be a total waste of material. Yes, beams are not harmed by small center drilling. Yes, all other aspects would be done to code.
But, is there anything against this idea?
Thank you!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
This happens all the time in steel frame buildings. No code issue. There are maximum run lengths before you have to up the gauge of wire but that's usually not an issue in residential buildings.
Thank you!
Sorry, updated with second question.
I acoustical caulked all the studs to sheathing/bottom/top plates based on this forum.
It seems there would be across bay darft if one of my bays sealing wasn't right because I'm opening the bays for the wiring. Is fire block foam in all romex drilled holes (only one line Romex) okay? I know this is in the weeds, but why do all the work on the acoustic caulking (which was a few hours) to just open a doorway for one failed area to draft it all.
Thank you!
Fire block foam or caulk would be required here. Each has its uses but the caulk is generally easier to apply.
Nice. I thought it was only for fire walls and plates.
Perfect. Thank you!
The code only really specifies physical protection for the wiring. If you're too close to the edge of a framing member with your wire hole, you need a nail plate. You have to fasten the wire within 12 inches of a box. etc.
The volt drop stuff in the code is a RECOMMENDATION, not a REQUIREMENT. It's recommended to limit volt drop to 3% on a branch circuit cable run like this, and that's between the source and the furthest device (outlet, in your case) on the run. I think what you're proposing doing with make a sort of star topology, instead of a simple daisy chain, so you'd actually be reducing the total wire run between the "furthest" outlet and the source, which would help you keep volt drop under control.
If you have lots of wires in a box, you get into BOX FILL issues. Every box is labeled in cubic inches, and the code tells you how many cubic inches you need for each wire, wire nut, etc. If you add all your stuff up in the big junction box and it needs more space than the box you were planning to use, you have to use a bigger box (sometimes you can use an extension ring to "expand" a box). Note that this box MUST be ACCESSIBLE too, you can't drywall over the top, you have to leave some type of cover (a blank cover, a cover with an outlet in it, etc.).
My guess is you're most likely to run into issues with the max fill for the box the other wires star out from. If you can recess this box, and only want a single outlet in it, see if you can fit a 4" square box (or a 4-11 box) with a mud ring, which would give a single device opening in the wall, but would allow a lot more interior box volume for connections to be made. Working through the small opening isn't fun, but this does satisfy code if you need more room for wires.
I agree with DC about the need to fire stop those holes. Fire codes in general are trying to limit the spreak of smoke and fire, so if you think your hole might allow for smoke/fire spread to somewhere that was previously blocked off, then it's a good idea to fill the hole with fire stop. The orange canned foam (Great Stuff) is listed for this purpose in residential structures. It is NOT suitable for use for the same purpose in commercial structures.
Bill
Thank you.
Yep to everything you're saying.
This is embarrassing, but I on purpose got 4x4 boxes with 1 device mud rings to eliminate any question about neatness or cu size :D
I even got a three gang box for the initial split. Total over kill. But no question I have the cu space. https://www.homedepot.com/p/Southwire-2-1-2-in-D-Steel-Metallic-3-Gang-Welded-Switch-Box-with-14-CKO-s-and-F-Bracket-1-Pack-TB-325-F-UPC/324516756. This is will play as my accessible junction box for the initial split.
Either this is extremely wasteful, or I am well ahead of the typical homeowner that the inspector always fails for good reason on the cu space requirement.
For single outlets, I got super deep boxes.
Extra room in the box will never hurt you, as long as the box physically fits in your wall :-D The only concern I could potentially see is that you may have to go to a supply house to get the plate you need for that three gang box. The box stores usually have only a limited selection of plates when you get above two gangs. I do know you can get blank covers up to 6 gang at the supply houses.
Bill
Oh, you're exactly right. HD doesn't carry the larger ones I needed. Amazon does in the same brands. 3 blanks for that grain fed box was at HD though. So score for me. (online option, but as you said, not available at my local HD store)
I have no doubt I'll fail something on the first go, but I am trying to be 100% educated so appreciate your time!
Also, so you know I'm not going to kill myself by helping a rookie not in the know, I do know about grounding to metal box and have the correct green screws. Just so we're all on the same page I'm doing it safe.
The only cringe worthy thing I plan is using wagos. Just so much easier even though wire nuts aren't particularly difficult.
Thank you!
Ideal makes some very nice grounding jumpers that have a ring terminal crimped onto one end with a green grounding screw preinstalled, and a spade terminal on the other. you cut off whichever end you don't need, strip the wire, and you have a nice grounding jumper. I highly recommend those -- they make wiring easier.
I do not trust wagos. My crews like them, but I specifically disallow their use in some places. If you really want to use them instead of wirenuts, I would at least use wirenuts on the GROUND wires in all the boxes.
Bill
Ha! I did warn I knew the Wagos would be the controversial design element :)
Bill,
Maybe I'm misunderstanding this, but both you and DC seem to be saying the holes for wiring between stud bays on walls need to be caulked. That's something I've never seen and I'm a bit unclear what the purpose is. Wires penetrating the primary air barrier, or between floors - get sealed, but here anyway, there is nothing that calls for sealing wires against fire spread, or to stop horizontal air movement, between stud bays.
I do wonder about derating when using fireblock. As I read it, derating is required with multiple romex lines in a fireblocked top/bottom plate.
I am only using one line through my bay holes. However, I asked because I was sure that draft blocking across bay holes is not required and might even be called out for doing foaming each hole?
I ask GBA because acoustic sealing seems like a waste since a bay could have a seal flaw and then you open the bays with a hole for wires. Into the weeds, but it wasn't like acoustic caulking was effortless, so why ruin the effort? Seems like an area to affect the acoustic caulking idea.
You won't need to derate wires where they pass through a hole. The wires have to share a common conduit or raceway of at least 24" in length before the derating rule applies.
Bill
Malcolm --
The IRC just says "At openings around vents, pipes, ducts, cables and wires
at ceiling and floor level, with an approved material to
resist the free passage of flame and products of combustion."
The reason I said "here" in my post is that in DC they require that if you drill a hole, you fill it. We have much stricter fire measures than most places, most residential construction now requires sprinklers.
Malcolm, what I'd meant is that if the horizontal hole connects two otherwise unconnected vertical passages and would bypass some other fire block elsewhere in either passage, then the hole should be filled. For most residential construction, "regular" holes in studs along a wall aren't an issue. DC, as in Washington DC, may well have stricter rules. Chicago requires that ALL wire be in conduit, even in residential structures. Different localities have different rules.
BTW, in commercial structures, EVERY horizontal penetration has to be filled, if it's in a wall that could be considered to be a fire barrier. Since a typical commercial wall is a 1 hour wall (5/8" drywall on both sides), if the wall goes all the way from the ceiling to the deck (or floor pan of the floor above), then it has to be fire stopped. We can't use orange great stuff for this, either -- we have to use intumescent materials (caulk, putty pads, etc.), rated for the purpose.
Vertical stuff commercially is more robust. On one recent project, I had a 3" sleeve through the floor between two floors (I think 6 and 7, might not remember that right). Anyway, the sleeve had to be sealed to the concrete floor on the top and bottom with intumescent fire stop caulk. The empty space inside the conduit had to be stuffed with mineral wool. A fire rated putty pad (intumescent again) had to be sealed over the top and the bottom of the sleeve.
There is a good reason why commercial buildings are much more fire resistant than residential structures: concrete and steel construction (mostly), multiple levels of fire barriers, fire rated assemblies pretty much throughout, robust fire stopping (until some bozo bashes a hole with a hammer...), and.... They're pretty much all sprinklered too.
Bill
Deleted
Actually, I am at a a total lose of how the my spray foam and canless (junction box built in) led lights are suppose to work.
I've read some inspectors require the canless junction boxes be attached to the rafter and some don't care. Yes it will be physical near the hole of the LED light, but never hear what you'r suppose to do if you're getting spray foam. But since electrical inspection comes before the spray foam on the cathedral ceiling...7 inches of spray in an 8 inch cavity....pull off the jbox from the rafter and leave it hanging for the foam person or just hope the junction box LED controller never goes bad and wish it luck in it's new foam cocoon?
Spraying over the LED junction box driver doesn't seem smart...
My only concern with stuffing the bay holes for electrical is there seems to be concern for space for multiple wires to breath. So I assumed even one line, with foam spaced in the hole would so constrict that it would be equal to too many lines in one small hole.
Energy efficiency or fire block, both are done for the same concept of limiting air flow...so....
I'm convinced this won't be an issue for my single drilled 1/2 hole per bay without derating worries. I'll spray foam these bored holes.
Thank you all!
You probably missed my response about this in post #18. The derating only applies to wires sharing a conduit or raceway of more than 24" in length.
You also have some extra margin with NM-B "Romex" cables, which use 90*C rated conductors, but are only allowed to be sized from the 60*F table in the code book. This means the cable has a 30*C (54*F) thermal margin. I think (my opinion here) that the reason for this is to give NM-B cabling extra margin for when it's operating buried in insulation, to make sure it's safe.
You basically have a very conservatively rated cable going through a very short length of hole, so you're not going to have any issues with heat, even if you fill the holes with foam. Note also that you'd have to run ALL the cables at FULL load at the SAME time even to get maximum heating. Chances are that none of those cables is ever going to run near full load for any appreciable length of time.
BTW, the only place I've ever really seen (or I suppose, felt :-) the heating of wires that is the reason for the derating table is in datacenter facilities at work. In these facilities, due in part to the way electrical power is sold to customers, it is common to run ALL circuits up around full rated capacity continuously. Special design considerations come into play in these facilities to allow for this to operate safely. We are able to run nine 20 amp 120V circuits in a single conduit safely using 12 awg THHN wire, although we normally only have 6 circuits in such a conduit. These conduits are noticeably warm to the touch, although not so hot that you can't leave your hand on them. Residential applications run nowhere near this heavily loaded, so don't worry about it.
Bill
You're exactly right I missed it. Thank you for the detailed follow up. Excellent help. Thanks a million for helping this stranger.
May I ask a follow up that will just hurt you noggin for how basic it is?
A raceway/bundling is where the wires share the same hole per bay or run. I think I understand that.
Where I have a double wall and room to spare with my branch heading off in different directions to avoid post drilling...is it within code to take those two lines starting the branch off in the same stud bay heading up in the same direction for the top plate to separate the lines stapled to opposite stud in the same stud bay?
Thank you!
A raceway is an enclosed assembly containing the wires. A conduit is normally a round pipe enclosing the wires. A hole is just a hole, it's not a raceway or a conduit.
You can route the wiring pretty much however you want in the stud bays as long as you support it as code requires, and use nail plates if the edge of your hole gets too close to the edge of the stud. The purpose of the nail plate is to prevent things like drywall screws from puncturing a cable that is close to the edge of the stud. The purpose of the cable supports is to secure the cable so that it stays where it's supposed to be.
Hopefully that answers your question, since I can't quite visualize what you're trying to do here.
Bill
Okay.
So if you have space, like I do with a double wall, you're good to run a few lines vertically up on one stud (as long as following the 1 1/4" stud face rule), next to each other, where each line is stapled independently...and that staple spacing is the only physical separation between the lines?
Just to clarify, I'm saying flat next to each other, NOT stacked on top.
Thank you a million!
You can get cable staples rated to let you run two runs of cable under one staple. There are also "cable stacker" clips like these:
https://www.amazon.com/3M-SI-1-Cable-Stacker-25-Count/dp/B001AWP7MI
available that can hold lots of cables. Caddy (a manufacturer) also makes a metal bracket that spans between studs allowing you to lace cables to the bracket in space between studs.
Running cables next to each other is fine, as long as you keep clear of the edges of the stud per code. Holes should be big enough for the multiple runs to pass through freely, without binding or stretching/tearing the jacket.
Running a bunch of cables in a stud bay isn't a situation where the derating rule comes into effect. You usually only run into the need to derate when running a number a large number of wires (usually 6 or more) in a single run of conduit. The rule can come into effect with cable trays too, but I don't think you'll ever see cable trays used in a residential structure.
The general idea of the derating rule is to ensure there is adequate air space around cables to allow for some level of cooling, so that the cables stay within the thermal limits of their insulation. This means you need a large number of cables packed very closely together (think about a bunch of wires in a single conduit), in a confined space (like a conduit) that doesn't really allow any air movement. As long as you have some amount of air around the multiple cables in a stud bay, you're fine.
Bill
Fantastic. You have set me straight and at ease. Thank you!
Started drilling the holes last night when the kids went down. Thank you. This was great info. Much appreciated and feel confident in what I'm doing.
Take care
Passed inspection!
Bill, the cable stackers recommended were fantastic. While not needed for stable spacing on my double wall construction, it just made the process so much neater and faster. I even used a few when I ran out of normal staples on a single line.
I will say, I caught at the last second that a rough electrical inspection means nothing is attached but everything is present. The inspector was fine with a few of my outlets already installed, but I did pull them all out of the box.
I fire putted the exterior wall boxes to air seal and that was fine. She said I was totally fine to go ahead and fire foam the stud bores because the fill was fine (two lines is the largest I had)
On the large box with one line in and 3 out, I left the wires pocking out and she asked how I was going to ground. I was confused by this because I grounded the box perfectly, but she was testing me on how to connect all the grounds. I figured it out that because my pig tail wasn't present, that was what she meant. Once I said that, we were good to go.
Thanks for all the help!
Glad to hear things went well for you! Regarding grounding, the inspector probably wanted to make sure you weren't planning to ground through the mounting screw for the device (in the case of a receptacle or switch). That hasn't been allowed now for a while.
Bill