We buy bare copper and grounding wire

Grounding is the least glamorous part of an electrical package and the most frequently left over. Bare copper grounding electrode conductors, green insulated equipment grounds, bonding jumpers for water pipe and structural steel, and tinned copper in industrial settings all accumulate in coils and short spools.

What makes a coil quotable is identity. A coil of #6 bare copper with a tag or a manufacturer wrap is a usable grounding conductor. A bucket of stripped conductor with no size and no source cannot be identified, so the tag or the print is what turns it into a quote.

We buy bare copper and insulated copper in sizes from #14 through 4/0 and larger, in coils, spools and cut lengths. Green THHN/THWN-2 grounding wire in 500-foot boxes is a common form.

Bare copper oxidizes. A dark brown or greenish surface is normal and does not destroy the conductor value, but heavy corrosion, pitting or green verdigris on stranded conductor suggests long outdoor storage and changes the assessment.

Photograph the coil in daylight, then a close-up of the conductor surface and the cut end. For green insulated wire, photograph the print and note whether the jacket is cracked at the bend.

Weight is a useful cross-check for coils, since length is rarely marked. A bathroom scale and a clear photo of the coil is enough for us to estimate.