What is the right way to strip power wires?

Question

I've been working with electrical circuits as a DIYer for years, including electronics and powerline work. But one thing I always feel like I do a terrible job at is stripping wires: both the outside jacket and the insulators from the conductors...

Perhaps I'm being over paranoid, but if I nick the insulators when I'm cutting the jacket, or if I nick or scrape the insulator I will cut back past this injury and start over. I want something that an inspector would give the thumbs up, because I might as well do it right while I'm doing it. But, this always tends to take a while to cut just through the insulator and not any further. I've tried tools from knives to sharp wire cutters to duller wire cutters to specific wire strippers.

My current mechanism is to just use a knife and be extremely careful while cutting the insulation or jacket, but it is fairly time-consuming and error-prone. Some jackets I get lucky on and there is a ground or nylon string in it that I can pull on to tear the jacket up to where I need it, then just clip it off. But some appliance cords that I work on have quite beefy 20A cables and those can be a bear.

Any hints or words of wisdom on what an inspector would red-flag me on?

Answer 1

First up, the only "right" way is to do so with the cable disconnected from the power and to do so without nicking the conductors. Beyond that there are a multitude of ways, with some being better than others on certain kinds of cable.

As an apprentice I was taught to use either pliers or a knife, depending on the cable, and have continued to do it that way ever since (about 42 years). Sure I've had to redo a cable from time to time because I nicked the conductor but I reckon that once I had the technique mastered that would be no more than one or two in a thousand cables.

Over time I've tried just about every kind of gadget and in general am less than impressed with most. Even those which worked well at first seem to deteriorate and become useless as either their cutters get blunt or they develop too mush slop in the moving parts.

Despite the forgoing, I suggest a person with an occasional need to strip cables use a commercial stripper. However, a person with a more regular need just needs to learn a couple of tricks (needs to be shown, not described in words) and practice. Just one thing to remember, pliers with sharp cutters work better than those with blunt cutters, and are also less forgiving of mistakes. Side cutters for some reason never work as well.

Answer 2

This is the stripper I use:

It's got cutouts for 14-2 and 12-2 NM cable sheathing and inner conductors, and a decent set of sharp bypass cutters near the hinge for cutting wire. It works better than anything else I've used for 14-2 and 12-2 Romex -- just squeeze, give it a little wiggle for good measure, and the sheathing pulls right off. It's almost impossible to nick the conductor insulation inside. For 3-way wire it's not so foolproof -- I use the cutter blades close to the hinge to score around the sheathing and then pull it apart. Probably as good as any other method and is still faster than doing it manually with a knife.

They also make a 12/10 gauge version and possibly others. I got mine at Lowe's.

Answer 3

This is one of those things that I think just takes practice, the more you do it the better you'll get at it. I've seen lots of different techniques, but even after being shown these tricks you would still have to practice them a bit before you got the hang of it.

Find a technique you like and practice it. Get some scrap wire and start stripping it, before long you'll have it down.

I've always had good results with a Wire Ripper like this, for removing the sheathing. Simply slip it over the cable, squeeze, and pull.

Another good technique for stripping NM cable sheathing, is to run a razor lightly down the center of the cable. You don't want to cut the sheathing, simply score it. When you get near the end of the cable (about the length you'll strip the internal wires at), cut deeper through the sheath. Now that you have a long scored line; and a small tear in the end of the sheathing, you'll be able to peel the sheathing like a banana.

Once you have the sheathing peeled, you can strip the individual wires with wire strippers like these.

Wire strippers like this can also be used for bending hooks into the wire, so they can be attached to terminal screws.

EDIT:

I recently picked up the Lil' Ripper Stripper™ from Ideal.

It touts being able to

• Rip Romex® wire outer jacket cleanly and quickly.
• Clip outer sheathing to remove excess Romex® wire jacket.
• Strip inner conduit wires.
• Looping holes loop wire for screw-on connections.
• Twist-Assist™ tightens most popular sizes of winged twist-on wire connectors.

I have to say, it did most of what it says very well. The only problem I had, was removing the sheathing after ripping it (though, even the guy in the demo video had difficulty, so I don't feel too bad). This is a solid multi-tool for any DIYer, and makes stripping cables (even those already in a box) easy.

You can read a full review of the Lil' Ripper Stripper™ on the DIY.StackExchange Blog

Answer 4

For plain old romex 12-2 or 14-2, I have tried various strippers and cutters, but always have the best luck just running a utility knife down the center, pulling it back and then cutting it off. Since the bare ground is in the middle, it rarely damages the other wires.

Answer 5

I use a self-adjusting wire stripper

Dead simple to use, and way faster than a manual stripper in my experience.

Answer 6

For stripping the sheathing, follow mohlsen's advice. That's the only way I know of stripping the sheathing, and it's the way just about every pro electrician does it, at least from what I've seen.

For stripping the individual wires, use the tool that James Van Huis recommends -- it's an awesome tool. With that tool, you'll consistent strip lengths and no knicks in the wires.

Answer 7

Coming from a real electrician all of these answers are pretty good. The best way, the only legal way, never ever score the wire, always strip with a flat part of your blade along the wire length. Scoring the wire creates weak points or hotspots. This would create heat, more resistance, and ultimately could end in a fire.