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This is a 1985 home wired with typical NM-B wire and plastic wall boxes.

I have a few light switches around the house that have no ground connection. There are ground wires in the box, but the switches themselves don't have a ground screw. I guess this was a valid thing to do at the time, but these switches need updating.

To ground the new switches, often times I need to run a ground pigtail from an existing wire nut to the replacement switch. And I'm running out of 14-gauge copper wire scraps to do that with. I've searched all the local big-box stores looking for 14 (or even 12!) gauge bare copper rolls, and I can't find any. I can get insulated THHN or NM-B with no problem, but stripping eight inches of insulation off of that seems like a real chore unless I'm missing a trick.

One thing I did see -- they sell rolls of green-insulated THHN in appropriate gauges and lengths. Since green universally means ground, can I use that for my application?

Separately from the question of whether it's code-compliant to do, if a seasoned pro came by later and saw something like that in the box, would they think the previous work was done by a knucklehead? I ask because I've never seen green wire used in residential wiring, either in this house or anywhere else I've ever lived.

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  • Some electronic switches (timers, motion sensors, etc.) come with green ground leads.
    – StayOnTarget
    Aug 12, 2020 at 11:49
  • @UuDdLrLrSs Yup, I've seen that type of thing a lot on light fixtures too. But never as part of wiring that's attached to the box or stapled to the wall studs.
    – smitelli
    Aug 12, 2020 at 18:54
  • I see what you mean - and I agree.
    – StayOnTarget
    Aug 12, 2020 at 18:55

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Green wire is perfectly legit. If you are really lazy or in a hurry you can even get pre-cut pre-stripped green grounding pigtails ready to go.

Ground is the only thing it can be used for, but "green or bare" is fine for ground nearly everywhere (I think there are some hot tub/pool specific cases where green is required and bare is not OK, but I don't have any detailed familiarity with those installations as I don't have one.)

Incidentally, it's trivial to strip long lengths of wire with a utility knife if you clamp the end of the wire and pull as you cut. I opted to go full conduit and have been using the NM that was partially installed as grounds (where needed - most of the grounds are the EMT conduit itself), and can strip a 12 foot chunk in less than a minute. I detest the scam where the THHN inside NM cable is not labeled as THHN so it cannot be used any other way...

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    If you want to get even lazier, you can get pre-cut ground pigtails with a terminal crimped on one end, so you don't even have to loop the end around the ground screw.
    – PhilippNagel
    Aug 11, 2020 at 14:30
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Yes,THHN is legit for pigtails, solid is a sure bet... or stranded, if you have the chops to attach it to a screw.

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  • I just replaced 2 dozen switches and they all had a floating plate to use as a clamp for stranded wire. It was a PITA, so I only used it a couple of times for when I didn't have a choice but to use stranded, like coming from a fan controller that also had a light dimmer I wanted to have controlled by a regular switch.
    – computercarguy
    Aug 12, 2020 at 20:52
  • Oh, but it's wonderful once you get the groove @computercarguy. I use the bolt shear to hold onto the strands and twist it quite tighter than you could by hand. At that point it's easy to put into screw-and-clamp's... I can even get it under screws that way. The payoff isn't then, it's when you're stuffing 12 wires back into the box!
    – Harper - Reinstate Monica
    Aug 12, 2020 at 20:56
  • I can totally understand more experience would make it easier. I'm simply a homeowner, not an electrician, so after replacing all the lever switches with flat switches, I hope to not replace them again for at least 10 years. :-)
    – computercarguy
    Aug 12, 2020 at 21:00

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