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What is the point of buying grounding wire? Question

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Many stores seem to sell "grounding wire". This is a solid copper wire, similar to normal THHN wires used to do house wiring, except without the plastic jacket.

I'm confused why you would bother buying grounding wire. Can't you just strip your normal wire as needed and get the same thing?

Grounding wire seems cheaper than jacketed wire, but only by a little. These savings are offset by the fact that you would have to invest in a separate spool of grounding wire, and they are not realized until you've actually used up a large amount of grounding and jacketed wire. I imagine for a contractor who lays down miles of wire, this is significant, but for a casual DIYer the price difference seems moot.

I suppose it is convenient that you don't have to strip it. But this is offset by needing to store yet another spool of wire. Also, stripping wire isn't hard.

Is there some fundamental way in which "grounding wire" is better for grounding than stripped solid THHN wire? Or is it just a matter of cost + convenience?

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Maybe for literal grounding? (1 comment)

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I'm confused why you would bother buying grounding wire.

Grounding wire is intended to only carry ground, which shouldn't ever be more than a few volts from other ground, like metal water pipes. There are many applications where it therefore doesn't need to be insulated. Not insulting it saves cost, so makes the wire cheaper.

If you use a lot of such wire, it makes sense to buy it as the cheaper grounding wire. If you would only use it occasionally, then stripping other wire makes sense.

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Stripping more than a few inches of wire is a lot of work. If you need 6 inches of 14 AWG or 12 AWG grounding wire in a junction box, you can use bare wire, green insulated wire, or strip a piece of other insulated wire (typically black or white). But for anything longer than that, use either green wire or bare wire.

Outside of the "short piece in a junction box" situation, there are only two uses for grounding wire:

  • The wire from the main panel to ground rods (outside) and/or copper water pipe (inside, but normally right where the water pipe enters the house). This is large wire. The exact size will depend on the size of your utility service and possibly other factors. 4 AWG is typical. Stripping insulation off of 50 feet of 4 AWG wire is not my idea of fun.
  • Ground wires for subpanel feeds or branch circuits in conduit. These are typically 8 AWG to 14 AWG, depending on the circuit size. A little easier to strip than 4 AWG, but still not a great idea for more than a foot or so.

In both of these cases, the people who usually use them are professional electricians. They will typically have 4 AWG ground wire for panel replacements. If they do much conduit work then they'll have smaller ground wires along with the matching sizes of black and white (and possibly other colors, depending on the type of work they do) of insulated wires.

Many electricians (it is very much jurisdiction and type of work - commercial vs. residential) do very little conduit work, in which case they have the 4 AWG ground wire, 14 AWG (for 15A circuits), 12 AWG (for 20A circuits) and 10 AWG (for 30A circuits) cables (typically both black/white/ground and black/white/red/ground) and they get other types as needed for a particular job. Most DIYers (outside conduit-only areas such as New York city) will never use conduit and never need a bare ground wire (except 6" inside a junction box).

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