Fastening Wire In Walls

Discussion in 'Electrical Forum discussion & Blog' started by molo, Jul 24, 2007.

  1. molo

    molo Member

    Messages:
    849
    Location:
    cold new york
    On securing wire inside walls... I have experimented with a cold wire and an open wall cavity. It seems that a stapled wire can't escape from a nail or screw, where a wire free in the wall cavity does. Why is it code to staple?

    TIA,
    Molo
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,560
    Location:
    North Carolina
    334.30 Securing and Supporting.
    Nonmetallic-sheathed cable shall be supported and secured by staples, cable ties, straps, hangers,
  3. frenchie

    frenchie Jack of all trades

    You wire shouldn't be fastened close enough to the surface to ever catch a nail or a screw. If it is, it should be covered with a nail guard.

    Off the top of my head... if it isn't fastened, work on a connection at the box can jiggle the cable, inside the cavity. NM might rub against a nail, screw, or other sharp object. BX might come to rest against a copper pipe, and start corroding. Or, the cable could just get moved closer to the surface, where a nail might hit it later.
  4. molo

    molo Member

    Messages:
    849
    Location:
    cold new york
    OK, Let me ask this, what ave. homeowner is going to know enough not to grab a 2 3/8" + screw and go to town hanging some heavy piece of art. Any screw over that length that wanders through the stud will penetrate a tightly secured non-metallic cable. This thread originates from a genuine concern about puncturin cable inside the wall cavity.
    Last edited: Jul 25, 2007
  5. BrianJohn

    BrianJohn DIY Senior Member

    Messages:
    151
    Location:
    VA
    Fastening cable, prevents damage to the cable when hanging drywall this also simplifies hanging drywall as we know from expierence drywall hangers will cut any cables in their way.
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Our walls are full of pipes and wires. Nail plates provide some protection as they pass through the studs. They do not protect cables and pipes which rise vertically between or next to studs. Careful and proper procedures will minimize damage, but nothing will ever completely prevent it.

    Around here, it does not freeze, so water pipes are routinely placed in outide walls. I don't remember any project where the stucco people DIDN'T put a nail or screw through the sheathing into a copper pipe!

    At home, due diligence on our part requires very careful testing before driving screws or nails. I start with a stud finder, but then always probe with a scratch awl to exactly find the edges of studs. If I can't drive a screw in straight, then I will have to accept the possible consequences.
  7. CHH

    CHH New Member

    Messages:
    225
    Location:
    Denver, CO
    That reminds me of the DIY hanging a cabinet in the bathroom of a new home. He carefully located the stud and then drove the screw. The next moves were shutting off the water and calling a plumber since he had hit a water supply line to an upstairs bath.

    The stud finder had indicated on the copper pipe and the guy was a careful enough worker that the screw was in the exact center of the tube. The guy did precise work, he just didn't know enough to realize that he had located a "stud" that wasn't a stud.

    Missing a stud is easy enough. I worked on a framing crew one summer while in college so I try to think about where the studs should be and go from there. What tricks do other folks use?
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,560
    Location:
    North Carolina
    what I do is

  9. molo

    molo Member

    Messages:
    849
    Location:
    cold new york
    LOL JW, You'd be surprised, well...... maybe you wouldn't.
  10. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,734
    Location:
    Central Florida
    Molo, I've been asking the same question for years. I even ran some tests with nail guns and power screwdrivers to see what would happen, and in every case the unsecured cable moved out of the way of the fastener being driven, and the secured cable was damaged. Duh.

    The approved methods of securing a cable when using steel studs leave the cable pretty loose, it seems to me, so there's nothing sacred about making it absolutely immobile.

    Securing the cable also makes it a bitch to alter the installation after the walls are closed up.

    However, there are provisions in the code relieving you of the requirement to secure a cable if the cable is fished, so that suggests a strategy...
  11. hids2000

    hids2000 New Member

    Messages:
    63
    Location:
    Belleville NJ
    is there a code for the distance between 2 cable staples? running the cable vertically on the side of a 2x4?
    I know I have to put the first staple within 8 inches of a plastic box, or 12 inches of a metal box, but what about between the first staple and the top of the ceiling?

    Assume the ceiling is 8ft in height.
    The plastic outlet box is 12 inches off of the floor. staple #1 is 8 inches higher.
    so when does staple #2, #3 and etc come into play?
  12. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,560
    Location:
    North Carolina

    334.30 Securing and Supporting.
    Nonmetallic-sheathed cable shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings designed and installed so as not to damage the cable, at intervals not exceeding 1.4 m (4½ ft) and within 300 mm (12 in.) of every outlet box, junction box, cabinet, or fitting. Flat cables shall not be stapled on edge.
    Sections of cable protected from physical damage by raceway shall not be required to be secured within the raceway.
  13. hids2000

    hids2000 New Member

    Messages:
    63
    Location:
    Belleville NJ
    great! just the info i need.
    thanks.
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