Sending wiring through attic space

Kelly Durfey

Hello,

I'd like to wire up a fan in each of two bedrooms in my house, something that my house is currently not wired for. My thought was to run them off a circuit containing my hall ceiling lights and an outlet and light in the attic (or crawl space, I'm not sure about the difference) as I already have exposed boxes up there and won't have to open a wall. (The fans will be operated with a remote switch on a different circuit.) But I'm not sure about the best way to do this.

My research shows two ways to get the job done:
1) Staple the wire to the wood, following the rafters to the fan mount stretched between two rafters.
2) Drill through the rafters and send the wire across the span between.

Option 2 seems less ideal as the wires are less secure and have a location that's not as identifiable. Of course, it'll use much less wire. Does drilling through the rafter create structural weaknesses?

Also, I have the loose powdery insulation up in the ceiling. Is it safe to bury a wire (attached to wood or not) in that stuff?

I'm confident that I can do the wiring myself. But I want to make sure I string the wire the right way, up to code.

Thanks,
Kelly

gregzoll

Best to drill through the rafters to pull the wire through, to the fan boxes. As for the controlling of the fans with the remotes, still suggest wiring in Switch legs to the rooms, for wall switches, located near the doorway as you go in the room. Just make sure that you measure twice and drill once. I thought that I had the middle of the top plate for the wall, that I was pulling an antenna coax down, and actually came out next to the edge of the wall & ceiling.

Do not have an extra extension for my flex bit, so went the other way. You could get by with a flex bit, with two 4 foot extensions on the bit, and drill up through the plate, so that you do not end up having to patch the ceiling like I did, when you pull the Switch legs for the fixtures.

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hammerlane

Why are you running the cable along or thru rafters? Do you mean the ceiling joist?

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hammerlane

There are rules to running cables in attic spaces.

320.23 In Accessible Attics. Cables in accessible attics or roof spaces that are suitable for storage shall be installed according to 320.23(A) and (B). Spaces that have no floor installed and are not accessible by permanent stairs or ladders shall be considered unsuitable for storage in applying the requirements of this section.

(A) Where Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) vertically of floors installed across the top of rafters or studding, cable shall be protected by substantial guard strips at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 3' horizontally of the nearest edge of the flooring installed.

4.) Substantiation: Attic spaces without flooring are not suitable for storage due to the fact that the finished ceiling below the rafters is unprotected and subject to damage by stored items. Residents are still likely to store items in spaces that are easily accessible (such as when permanent stairs are installed) despite having no flooring.

Under the 2005 NEC, cables in attic spaces that are not readily usuable for storage spaces are being needlessly protected against damage that will not likely occur. Revising this text will be as effective, while relieving installers from the requirement to protect cables where no such protection is necessary.

In addition, the removal of the reference to the term "AC cable" in 320.23 will provide clarity in relation to other articles that reference this code, such as 334.23. The term "AC cable" is unnecessary in this context, as it is located in the article by the same name.

gregzoll

For one, I was tired, and two the OP will realize the difference after they go up there and figure it out. Most people think of the whole unit when they are manufactured trusses as both the top & bottoms being rafters, due to that is how they grew up being told, or when talking to people.

I always say Rafters, when telling someone what I am doing up in the attic, but I know what I am actually thinking about, when I am working up there. I am sure the OP will too.

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mr leak

Yes you can run wiring such as romex thru the attic insulation. Not sure why you would have to drill a hole thru the rafter The romex can just lay on the top of the ceiling joists The romex needs to be stapled within 8 inches of where the fan box is installed with a proper rated box for fan application due to the anticipated weight and have a proper fitting where the wire enters the box

Kelly Durfey

Thank you for the clarificiation on vocab. I was debating whether to call them rafters or joists in my original message, but I also know that they came preassembled, so rafters it was.

And I'll be taking an outlet off an existing switch to gain access to the mounted switch box.

My space has just a bit of flooring underneath our air exchanger for the sake of any visiting technicians. That makes it "unsuitable for storage", which I get. According to the code below, I'm still expected to follow the 3' rule, as unnecessary as it might seem.

Can you tell me if this is right:

Since my space is not a usuable storage space, I should only need to worry about the 3' rule when going across the top of the joists. So I can run the cable down the broad side of the centermost joist until I meet the 3' requirement and take a right turn to send it to the fan box. Since I've met the 3' requirement, Can I staple the cable to the top of the joist or do I still need to drill?

Thanks,
Kelly

mr leak

Just snake i.e. lay the romex to where you want it on top of the ceiling joists/rafters thru the insulation is fine Not a storage area so protection is not an issue staple it with approved romex staples and don't smash the wire only enough to secure. Most important is have the proper box to support the fan weight Most of these boxes have 35 # rating or are metal boxes secured to solid blocking between the rafters
Hope this helps The wires are not "going "anywhere Secure within 8 inches of the box

Kelly Durfey

Thank you, Mr. Leak. That's exactly what I needed.

ericmunyon12345

You're missing the code that Hammerlane said. No problem, but if you want code, you need to run two furring strips, like one by twos. One on each side of the wire so no one can step on or damage it.

mr leak

Only need furring strips if persons are liable to walk in this area and understood hopefully correctly that this was not an issue Wiring subject to impact of coourse does need protection

kbsparky

Preassembled usually means trusses. Those are specifically engineered and should NEVER be drilled.

Staple the wires to them, but don't drill `em.

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gregzoll

Find me one home that has engineered trusses, that does not have holes drilled through the center of the 2x4 or 2x6 bottom timber of the system. You will not find any that do not have holes drilled through the joist section of engineered trusses.

The problems occur, when people start drilling holes towards the top or bottom, same if they were floor joists.

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mr leak

you will not find any homes that I built in the last 30 years that have any holes drilled thru any truss members except one that the idiot home owner did to rum some speaker wires without asking NOT ALLOWED period

Jim Port

Your inspectors must be quite lax. Trusses should not be drilled.

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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.