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I have a package of Gardner 1/2 inch staples and the package shows that they are good for 2-wire, see below:

enter image description here

I am running some 14/3 wire (flat) wire for AC hardwired smoke detectors but these staples are all I have on hand. I've stapled the 14/3 using these and the 1/2 inch is just enough to fit the wire without pinching it. I can even slide the wire back and forth fairly easily. FWIW, I read the package after stapling about 100 feet of wire. See below for an example:

enter image description here

Is it necessary to use 3/4 inch staples instead? What is the hazard associated with using the 1/2 inch staples? I'm not sure how much copper expands when heated but I can't imagine that it would outgrow the 1/2 inch. Is it more of an issue that people tend to pinch and/or impale the wire while hammering so the 3/4 inch is an attempt to reduce errors? I can definitely see the need for using 3/4 inch for 12/3 wire but I haven't run any.

My walls are currently wide open so if I should be using the 3/4 inch staples then right now would be the best time for me to make things "right".

Additionally, can I use the 3/4 inch staples for 2-wire? I'd rather simplify the contents of my electrical bag.

enter image description here

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I've used them myself, and I would be careful trying to cram a /3 into a staple for a /2. The danger there is your pinching or clipping the outer sheath of the cable (or, worse, accidentally having a nail go through the cable). The inverse isn't true, however. I've used /3 staples on /2 wire without issue. The main thing is they want the wire secured to the stud. Even the appropriate size staple will allow smaller cables (like 14/2) to move some. This answer quotes NEC and mentions nothing about size vs cable.

Since these packages aren't terribly expensive (about $3 for 50 that fit /3) I would buy the ones that fit and avoid any questions later. Used properly, these are safe.

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  • It's not the cost that bothers me, it's the labor effort. I have maybe 15 staples in my wall cavities so I'll re-do those but I might leave them alone in my open basement and open attic. I was extremely cautious not to pinch nor impale the cable and verified each staple by making sure the wire was able to glide back and forth behind the staple. – MonkeyZeus Jan 27 at 14:05
  • I edited my question and added a picture of my work. – MonkeyZeus Jan 27 at 23:33
  • @MonkeyZeus I didn't want to say it, but I had thought that 14/3 might fit in that smaller staple and apparently it does. TIL – Machavity Jan 28 at 0:00
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The problem is that the staples are UL listed for the wire sizes shown on the package. Technically, you'd need the 3/4" staples.

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    "Technically" as in using them per my description creates an active hazard or as in a code guy would point out the technicality? – MonkeyZeus Jan 27 at 16:23
  • Technically as in code guy, especially if he gets upon the wrong side of the bed. Your description sounds great but it's against instructions. – JACK Jan 27 at 17:11
  • I edited my question and added a picture of my work. – MonkeyZeus Jan 27 at 23:33
  • Sometime you have to look at the instructions or data sheet proper. They often simplify instructions for the labeling. Like many fluorescent ballast stickers will list 4 sizes they work with, but when you look at the instructions, there are like 30 sizes... – Harper - Reinstate Monica Jan 28 at 0:27
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If the cable, and its casing fit into the 1/2 inch staples, and by you even mentioning that you can pull them through is definitely ok. I would go so far as to say, that if you can easily pull the wiring through, its too loose, generally speaking, when fixing external cables to batons / trellises, or wooden beams / struts etc, the wire should fit snug, so you can keep the cabling as taught as possible between staples, you should be able to pull through slack or create a little through the last staple only at any point during the installation. Doing some research and based on same practice here in South Africa, the sizes on the packages, are for ease of use in this case, not for regulation sizes, i.e. Regulation states that wiring should be stapled, and preferably not with wire only / steel only staples. It however does not dictate what size staples must be used for what size / type of wire. IMHO, if you're doing a decent job, i.e. not leaving wiring hanging all over, with loose loops here and there (excluding for future plug points etc) then there's no need to worry about whether or not the ones you are using are the right thing for the job. Once again, as far as the 2 core wiring is concerned, I would go by the same as above. If its doing the job it was intended for, i.e. fixing the wiring to the wood, and keeping it tightly in place, then it should be ok. I only say this, because in this case, the staple to wire sizes are not regulated. It comes down to what you are comfortable with, as long as the job is being done property. This is after all, electric were talking about. Hope this helps, and good luck with the rest of it.

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    Welcome to the site. Please add some line breaks to form obvious paragraphs when writing a detailed answer. One big block of text is hard to follow and many people might not read what you have written. – JPhi1618 Jan 27 at 15:38
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In the NEC cable assemblies, like NM or MC cable, the description only describes the current carrying conductors although the additional ground wire is present. (This is not true for "cords".)

As an example as this applies to product marketing look at this graphic from Southwire, the image at the top for a ceiling fan says 12/3, you can see the picture has 4 wires. While the image at the bottom for wall switch and receptacle says 12/2, and you can see three wires.

Your picture looks like 14/2 NM cable (or pre-2001 12/2), if that is what you have then as indicated on the package should work fine.

If your cable is actually 4 wire 14/3 cable the staple package bears a UL label, listing is only valid when installed as approved, and would not be acceptable to NEC standards.

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    It's a 14/3. There's a black, white, red, and bare copper cable inside the sheathing. – MonkeyZeus Jan 28 at 18:49
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DON'T drywall until you replace that wire with 14/3 red, black, white and bare(uninsulated)ground. The 14/3 you have is insulated ground according to what I see online. Fire alarms require black(a/c 120volt live,white neutral and red for the signal wire between smoke detectors so if one detects smoke they ALL GO OFF. I'm a Canadian electrician so if this is incorrect I will apologize in advance, but I really think you should check with a local electrician about this.

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