I needed to splice a wire to repair nicked wire insulation, but I didn't feel like running to Lowe's just for a junction box. Instead, I used a regular electrical box.

Sorta junction box

The wire comes up from the floor and into the bottom of the box. The repair piece comes in from the top and will be wired up to the electrical outlet. I twisted the wires together with pliers and nutted them all up real tight. There are no exposed conductors outside the nuts.

I flipped on the power and, to my surprise, it worked! However, before I seal up the wall, I want to know if I did this right.

  • 1/4" of cable sheath in the box, 6" of exposed wire, that's what I learned.
    – Tester101
    Commented Feb 5, 2012 at 3:33

5 Answers 5


It looks good, but the romex sheath on the bottom cable has to come into the box for it to be correct. I can't see that area to make that call, but if you have sheath then you have done good.

  • 2
    Also the Romex cables should be stapled a few inches within the box.
    – SteveR
    Commented Feb 4, 2012 at 21:24
  • 1
    youtube.com/watch?v=3d9A_s3AA9Q Also homedepot.com/h_d1/N-5yc1v/R-100174976/h_d2/… I won't circumvent codes, they are there to protect the homeowner - not to fool an inspector. Stapling the box is code!
    – SteveR
    Commented Feb 5, 2012 at 1:38
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    @lqlarry - The box he is using does not have a romex clamp. If he does not staple the wire to a stud, there is nothing preventing someone from pulling that wire out of the box, perhaps from a ceiling below! Wires are tugged upon during construction all the time.
    – SteveR
    Commented Feb 5, 2012 at 12:47
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    @oscilatingcretin - No, you staple the wire to a stud within 8" of the box, the wire does not get stapled inside the box. This is to prevent someone down the road from tugging on to the wire, pulling it from the box, and creating the wires to short out! All boxes require the Romex to be stapled before the box, it is even more important with you're box, it has no wire clamp! Boxes with wire clamps are often pushed into the wall (old work boxes) where no staples can be placed, but they have the clamp to prevent the wire from pulling out of the box.
    – SteveR
    Commented Feb 5, 2012 at 12:50
  • 2
    The wires coming up from the bottom look way too short. You should consider replacing the cable from this box to the lower receptacle so you will have enough length in each box. The grounds should have a copper crimp or green wirenut. The wires need to be stapled within 8 inches of the box, or use an old work box metal or plastic with internal cable clamps. Commented Feb 5, 2012 at 13:32

This is not really an answer (well it sort of is), I just wanted to clear some things up from the comments.

First those little tabs covering the holes in some plastic boxes, are NOT knockouts. They are clamps. In this case, however, they do appear to be knockouts.

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If they were clamps you'd push the cable into the box past the clamps, then the clamps prevent the cable from being pulled out of the box. They can be a pain in the butt to work with, but they hold the cable fairly well.

Second, lets see what NEC 2008 says about securing the cable.

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 (4 1⁄2 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.

(A) Horizontal Runs Through Holes and Notches. In other than vertical runs, cables installed in accordance with 300.4 shall be considered to be supported and secured where such support does not exceed 1.4-m (4 1⁄2-ft) intervals and the nonmetallic-sheathed cable is securely fastened in place by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other nonmetallicsheathed cable termination.

FPN: See 314.17(C) for support where nonmetallic boxes are used.

(B) Unsupported Cables. Nonmetallic-sheathed cable shall be permitted to be unsupported where the cable:

(1) Is fished between access points through concealed spaces in finished buildings or structures and supporting is impracticable.

(2) Is not more than 1.4 m (4 1⁄2 ft) from the last point of cable support to the point of connection to a luminaire or other piece of electrical equipment and the cable and point of connection are within an accessible ceiling.

(C) Wiring Device Without a Separate Outlet Box. A wiring device identified for the use, without a separate outlet box, and incorporating an integral cable clamp shall be permitted where the cable is secured in place at intervals not exceeding 1.4 m (4 1⁄2 ft) and within 300 mm (12 in.) from the wiring device wall opening, and there shall be at least a 300 mm (12 in.) loop of unbroken cable or 150 mm (6 in.) of a cable end available on the interior side of the finished wall to permit replacement.

314.17 Conductors Entering Boxes, Conduit Bodies, or Fittings. Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with 314.17(A) through (D).

(C) Nonmetallic Boxes and Conduit Bodies. Nonmetallic boxes and conduit bodies shall be suitable for the lowest temperature-rated conductor entering the box. Where nonmetallic boxes and conduit bodies are used with messengersupported wiring, open wiring on insulators, or concealed knob-and-tube wiring, the conductors shall enter the box through individual holes. Where flexible tubing is used to enclose the conductors, the tubing shall extend from the last insulating support to not less than 6 mm (1⁄4 in.) inside the box and beyond any cable clamp. Where nonmetallicsheathed cable or multiconductor Type UF cable is used, the sheath shall extend not less than 6 mm (1⁄4 in.) inside the box and beyond any cable clamp. In all instances, all permitted wiring methods shall be secured to the boxes.

Exception: Where nonmetallic-sheathed cable or multiconductor Type UF cable is used with single gang boxes not larger than a nominal size 57 mm × 100 mm (2 1⁄4 in.× 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box measured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (1⁄4 in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening.

So what does this all mean?

334.30 says we have to secure the cable every 4 1/2' and 12" from each box, however, 334.30(B)(1) says if we are fishing the cable through finished surfaces the cable does not have to be secured. So we can have an unsecured cable in the wall, but 314.17(C) says if we are using a nonmetallic box the cable must be secured to the box (this is where the clamps come in). The exception to this rule, is if the cable is secured within 8" of the box. If we secure the cable within 8" of the box, we don't have to secure the cable to the box.

  • Is there a way to secure it within the box as it is considering I knocked out the knockout that the wire is coming in through? I really don't feel like switching the wire to the other hole as I have about had it with electrical =\ Commented Feb 5, 2012 at 16:02
  • NO--if you look more closely you'll see this is not one of the "old work" boxes with the ears and the integral cable clamps. Those are knockouts. Commented Nov 29, 2014 at 23:39
  • @Tester101 Believe me, I know the difference, this one looks like boxes I've seen that just have 4 small tabs holding the knockout in place, definitely NOT a clamp. The one here is definitely a clamp. Commented Nov 30, 2014 at 0:52
  • @Tester101 Another giveaway (not 100% reliable, but close) is that the OP's picture CLEARLY is not an "old work" box with the screw-down tabs to hold it in place in drywall, and for the most part those boxes are where you find the built-in plastic clamps, because you obviously can't get inside the wall to staple the NM cable to the stud in those cases. Commented Nov 30, 2014 at 0:55
  • ...the little ridges on the underside of the knockout just make it easier to lodge a screwdriver against them to push them out. Commented Nov 30, 2014 at 0:57

Uh - you can't seal up the wall. You have to leave that junction box accessible. Right guys?

  • 5
    Who said anything about sealing it up? It's going to have a blank outlet cover. Commented Feb 26, 2012 at 5:05
  • 2
    Sorry about that, I jumped to a conclusion when you said "before I seal up the wall"
    – BrianK
    Commented Feb 27, 2012 at 6:08

Once again, the box he is using is a "new work" "handy box" it is only a knockout and not a clamp! Therefore the 8" staple rule applies! With this type of box it is required to staple within 8", a box with a clamp is 12"! An "old work" Handy box would have a clamp as well as plaster ears with a screw device to secure the box

Notice the "Clamp" type box Notice the "Knockout" type box

See Tester101 code quote "314.17 C Exception... Says it all! Looking at his picture, I see no clamp on the wire! If it was there, it aint now!

  • It is a clamp. Notice in the "specifications" section on the linked page for "Knockout type box" Clamp type : V Clamps. In the "specifications" section of the other box Clamp type : Integral Clamps. And on both Number of Knockouts : 0
    – Tester101
    Commented Feb 5, 2012 at 18:29
  • I don't know what they refer to as a "V clamp", but by not saying it is integral suggests some type of aftermarket clamp. I have a box of these, they are not clamps. Take a look next time you go to you're big box store. In any case, his picture clearly shows no sign of a clamp, whether it was there or not.
    – SteveR
    Commented Feb 5, 2012 at 18:36
  • @oscilatincretin - Does the box have a plastic clamp that will prevent the wire from being pulled from the box? Did it have one that you removed?
    – SteveR
    Commented Feb 5, 2012 at 18:48
  • It looks like he broke the clamp off when he inserted the cable.
    – Tester101
    Commented Feb 5, 2012 at 20:20
  • The knockouts in this box are different than knockouts in other types. It only had one flimsy piece of plastic on either side of the knockout tethering it to the box (it's the tiny piece you cut with a utility knife). Once you break one, the knockout tab just dangles around. Other boxes I own have two stronger pieces tethering the tab to the box on two sides of the tab. When you cut two, the tab is pushed in, but the remaining tethers still hold strong. I don't know what you call those little pieces. They're kind of like perforation. Commented Feb 5, 2012 at 20:39

"I needed to splice a wire to repair nicked wire insulation...."

I appreciate this discussion, but I will contend that there was NO NECESSITY to cut the cable and try to put it in a box. In fact, I think there is much more risky to have done so. Unless the conductor was appreciably damaged, I contend that simple application of wraps of electrical tape which adequately protected the conductor(s) from shorting-out to one another, and/or the [metal] building, metallic piping, etc., or else presents any kind of shock hazard to building occupants should be proper to use.

I was taught, and my experiences in Fire Investigation have proved, that Good Terminations are the most important things an Electrician does day-in and day-out. This is of course aside from proper sizing of circuit-elements such as breakers and wires. Splices in a circuit are therefore much worse to do than a simple insulation repair.

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