Nicks create a place where the wire might break while bending when bending loops for screws. If it does not break, the nick probably is not serious. Practice on some scrap to improve your technique.

Practice on some scrap to improve your technique.

Words to DIY by.

Sounds like you need a new/better stripper, perhaps even a pliers-format one with a fine adjustment screw, as electronics techs use. I use that type in tight spaces, where I don't have "free swing space" perpendicular to the wire.

Regardless, there's definitely a workable margin 'tween nicking the copper and cutting far enough through the insulation that a minor tug-stretch will slide it off the end.

Tools hint: Klein is your friend, Harbor Freight/Made in ChiComistan is NOT. ;')

Is there really proper "technique" when using these kind of wire strippers? I thought they were fool-proof

BTW, this pic is of the exact stripper I have (the top red handled one) http://www.girr.org/girr/tips/tips6/tool_tips/wire_strippers.jpg

Here is a link that might be useful:

The best technique with those strippers is to deposit them in the nearest trash receptacle and get a good pair. Klein makes several models, here is the first one that I found.

Here is a link that might be useful: Klein

So, will I be OK leaving the wiring as-is, or do I need to re-strip and re-connect everything?

I attached a picture below. A couple of my nicks were close to this one. None of the wires broke when I bent them, or connected them, though.

Here is a link that might be useful:

As long as the nick is not all the way around the wire and small as the one you appear to have it should not be an issue.

A lot of the cheaper strippers do not have a solid enough stop to prevent nicking wires.

Another trick is to slightly rotate the stripper after it is closed to cut all the way around the insulation.

The 90C NM insulation (THHN type) is harder to strip than the older 60C PVC stuff.