BARE COPPER AND GROUNDING CONDUCTORS, #14 TO 4/0 AND LARGER

What Counts as Grounding Wire

Grounding conductors are the copper that carries fault current and holds metal parts at earth potential: the grounding electrode conductor from the service to a rod, plate or water pipe; equipment grounding conductors in every raceway and cable; bonding jumpers around meters, disconnects, gas piping and structural steel.

The stock is unglamorous and it accumulates quietly. Most of it arrives as part coils rather than full reels, and most of it is short enough that a contractor would rather sell it than store it for another year. We take the short pieces as readily as the full reels.

• Bare copper, soft-drawn or hard-drawn, solid and stranded, 14 AWG through 500 MCM.
• Green insulated THHN, THWN-2 and XHHW from 14 AWG through 4/0 and larger.
• Green with a yellow stripe for isolated ground circuits.
• Tinned copper for corrosive locations, washdown and coastal work.
• Bonding jumpers, braided copper strap and severed lengths of grounding conductor.

Sizing Comes From the Table

Sizing is not a judgment call. A grounding electrode conductor is sized from the largest ungrounded service conductor using Table 250.66, and an equipment grounding conductor is sized from the overcurrent device using Table 250.122. That is why a 200 ampere service with 2/0 copper conductors takes a 4 AWG copper grounding electrode conductor rather than a 6.

The tables climb in steps, and the steps are where surplus lots get misdescribed. A coil of 6 AWG copper is a grounding electrode conductor for a service up to 1/0, and the same coil is an equipment grounding conductor for a 200 ampere feeder. Both are real uses, and neither justifies overstating what the wire is.

Bare, Tinned and Green

Bare copper is the default for grounding electrode conductors because it can run without a jacket through a building, down to a rod or into a concrete-encased electrode. Green insulation is the default for equipment grounding conductors inside raceways and cables, where identification matters and the conductor shares a raceway with current-carrying phases.

The color is not decoration. Green, green with a yellow stripe, and bare are reserved for grounding and bonding, and a green conductor cannot be re-identified as a phase conductor in the field. That is why a coil of green 2 AWG suits one buyer and a coil of black 2 AWG suits another.

• Bare: grounding electrode conductors, ground rings, rod and water pipe bonds.
• Green: equipment grounding conductors in conduit, cable and tray.
• Green with yellow stripe: isolated ground receptacles and sensitive equipment.
• Tinned: corrosive atmospheres, washdown areas and some industrial specifications.
• Stranded for anything that bends or moves; solid for short, straight runs.

Clean Copper Is Not Scrap Copper

Clean copper is a commodity and wire is a product, and they are not valued the same way. A stripped, baled load of bright copper is sold on metal content. A coil of 4 AWG bare copper still on its tie, with a tag, is sold as 4 AWG grounding wire, and its price reflects that it can be installed next week.

That distinction cuts both ways. Copper that has been stripped, chopped and mixed is scrap, and general scrap metal is outside what we buy. Copper that is still wire, in a coil or on a reel, is a product and can be quoted. Mixed loads are separated on inspection and only the wire is priced. Photograph it before you cut anything, and send the pictures through the quote form.

Photograph and Note

Photograph the coil with its tie and tag, then photograph the cut end. Size is judged from the conductor and condition from the surface: a green patina on bare copper in a humid building is normal, while pitting, nicks and white corrosion are not.

Conductors are what we buy, not the equipment they connect. Transformers, switchgear, breakers, motor control centers, generators, chillers and machinery are outside that offer, and so is loose scrap metal. Grounding conductors usually travel with building wire in the same lot, and the how it works page explains how photographs become a number.

• The coil or spool with its tag and marked length.
• A cut end beside a tape measure for anything above 2 AWG.
• A part coil laid straight, so kinks and bends are visible.
• Any green or white corrosion, photographed close rather than avoided.
• Whether the wire is bare, tinned or green insulated, stated in the note.