How to Strip Single Conductor Insulation

How to Strip Conductor Insulation as Electricians (Strip NMD90 Wire)

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There’s many ways to strip the insulation off of a conductor, whether that be basic wire strippers, pliers, or even a knife.. in this article, I will share with you my favorite way to strip wires to prepare them for splicing!

Again, this is part of my electrician’s guide to cutting-in series!

How to strip single conductors as an electrician!

What We Cover in this Article:

  • Understand the Cutting-In Process
  • How to Strip Wires as an Electrician
  • Useful Tricks to Remove Conductor Insulation from Wires
  • Keeping the Integrity of the Wire (Copper is Fragile!)

Understand the Cutting-In Process

Before we start, make sure you understand the full process of “cutting-in” as an electrician. This means the correct wire has been pulled and stapled, you’ve installed your electrical box, and NOW you’re ready to “cut the wires into the box”.

The first step is removing the wire jacket (sheathing), then you push the wires into a box with the proper connector (or if the box has it’s own holding mechanism!). From here, I suggest organizing your wires (don’t have everything crossing), and make sure the wires are labelled.

You’re now ready to strip the wires (conductors), which is what this article covers, and the final step is actually splicing the wires, then tucking them back neatly into the electrical box!

How to Strip Wires as an Electrician

These are my favorite wire strippers.. learn more in Greenlee vs. Klein Tools video.
There are many ways to strip wires, which I’ll break down below.

The first thing you NEED to know is that the INTEGRITY of the wire is EVERYTHING as an electrician. What this means is if you score the copper too hard with your wire strippers, it can become very fragile and break!


Example of how I’ve seen many apprentices strip wire! (A big no-no!!!!!!)

By rotating your wire strippers and being aggressive like in the video above, you will SCORE the wire harshly. This is very bad as the copper becomes very fragile and can break off easily!

In the video below, I show how to strip conductor insulation cleanly without scoring the copper. Notice I use my thumb to help PUSH the strippers, which helps tremendously:

An example of how to strip wires properly with wire strippers.
(No scoring will happen if you use the right slot for your wire size!)

The second thing you need to know is WIRE SIZE.

If you are using wire strippers, there is a SOLID and STRANDARD gauge guide.. and make sure to follow it depending if you are using solid or stranded conductors!

This wire gauge guide is called AWG (American Wire Gauge)..
(Wikipedia says “also known as the Brown & Sharpe wire gauge.. used since 1857”).
The smaller the number the BIGGER the wire! #18 is smaller than #8 (oven wire)!

If you follow those two golden rules of stripping wire, you’ll have strong copper wire in your installations!

To repeat, those rules are..

  • Don’t be HARSH on the wire when stripping (if the copper is scored, cut it off and re-strip it!)
  • Make sure to use the correct wire size stripping slot! (If you’re unsure, simply close the wire strippers, and push in the wire to test the proper wire size in the wire strippers!)
An example of showing the wire pushed into the wire strippers to find the right sized slot!

Step-by-Step Instructions for Stripping Conductors:

I simply close the wire strippers to initially “cut the insulation” off the wire.

I then slightly remove cutting force so that it doesn’t rub on the copper wire when it slides off. (I still have the strippers closed, but I release tension just a little bit!).

I then use my thumb to push the wire stripper as I remove the wire’s insulation to expose the copper!

Useful Tricks to Remove Conductor Insulation from Wires

I will share a couple ways I’ve seen electricians remove the wire insulation in this section.

My personal favorite way is to use wire strippers (which I just explained above!):

This image is taken from the “Properly Strip Wire” video above.

Sometimes when bonding wire, you need to strip two sections and use an electrical knife to expose the insulated bond wire. This is convenient so you don’t have to create an extra pigtail. You can simply bond the cut out part, then you are left with a bonded pigtail!!! (See below):

Make two cuts with your wire strippers and remove the cut insulation to expose the copper to attach to the bond screw!
Wrap the cut out insulation CLOCKWISE around the screw.. tighten it down, and you have a bonded pigtail! 😲

Another approach to stripping wires is using electrical pliers.. I’ve never totally liked this way as I feel it’s really easy to score the wire.. but if you’re good at it, it works!

There are other types of wire strippers, like automatic wire strippers (self-adjusting wire stripper).. at the end of the day, it’s whatever works for you, but the wire strippers with the yellow tips are my absolute favorite wire strippers!

Keeping the Integrity of the Wire (Copper is Fragile!)

As mentioned, when you score the copper, it becomes very fragile when you move it back and forth over and over. I just want to REALLY stress that!

I saw this OVER AND OVER with many apprentices! (And the problem is they didn’t realize.. so it’s not that they’re bad workers.. they just weren’t taught this!!! So now you know!!)

This is a BAD score in the copper wire. This should be cut off and re-stripped to keep the integrity of the wire!!

If you watch the main video above, you will see I show you many times when copper is scored, it only takes 1-3 back and forth movements to break the copper!

Only 1 1/2 back and forth harsh movements makes this copper wire SNAP because it was scored by using the WRONG slot (too small of a size) on the wire strippers.

If no scoring is apparent on the copper wire, it takes about 8-9 hard movements for the copper to break.. so that’s like 5-6 times stronger if the copper IS NOT SCORED! (Also, this score has a potential for arcing and fires many years down the line..)

Copper wire is strong if it’s not scored! (This takes about 8-9 harsh movements to break the copper!!!)

How to Strip Copper Wire Properly..

Thanks for reading!
Valuable tips for how to strip residential NMD90 wire for electricians.

So there you go!

If you strip the wire without scoring it, you’ll have STRONG copper, and a great install for YEARS to come.

Make sure to start at the beginning of this Cutting-In Series for Electricians, and watch how to strip the jacket off the wire (this article is on step #2!)

Thanks for reading and watching. I hope the website has been helping you to become a better apprentice electrician! 💡

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