Equipment grounding conductors: green insulated and bare

Green means one thing only

An insulated equipment grounding conductor is green, or green with a yellow stripe, and it may not be used for anything else. That single rule is why grounding wire is so often left over: a crew buys a coil for the ground path, uses part of it, and the remainder cannot be burned up on a phase conductor later.

The conductor itself is ordinary copper, usually stranded above 10 AWG, with the same thermoplastic insulation as building wire. Some of it is dual marked and can be used in wet locations; some is not. The print on the green jacket tells you which, in the same repeating string as any other building wire.

Sizing does not follow the phase conductor

A common mistake at the desk is to assume the ground is the same size as the hots. It is not, above a certain point. The equipment grounding conductor is sized from the overcurrent device protecting the circuit, not from the current-carrying conductors, which is why a 4/0 feeder often carries a 2 AWG ground.

That has a practical consequence for surplus. Big feeder jobs produce small grounding conductors in quantity and large ones rarely. A pallet of green 6 and 4 AWG out of a distribution upgrade is normal and useful; a coil of green 4/0 is unusual and usually came from a service or a grounding electrode run.

Bare grounding inside cable and tray

Not all equipment grounding conductor is green. Cable assemblies carry a bare ground, and tray and pull boxes often use bare conductor for bonding. Bare grounding conductor is pulled from the same reels as any building wire and is identifiable only by size, which makes it the part of a mixed lot that gets mis-sorted. A bare grounding conductor pulled alongside phase conductors also carries their jacket marks, and often a film of pulling lubricant that has to be wiped off before the copper can be judged.

There is also the bonding jumper: short lengths, often with a lug already crimped on one end, made up on site for a door, a disconnect or a section of tray. Those are more assembly than wire, and they should be listed as such rather than tossed into a coil pile where the lugs will punch through the insulation of everything around them.

Sorting a mixed grounding lot

Grounding lots are almost always mixed, and they are mixed in a specific way: many small coils, several gauges, green and bare together, and a handful of jumpers with lugs. The sort is quick if the sizes are stated and slow if they are not.

• Gauge and whether the conductor is stranded or solid
• Green insulated or bare, counted separately
• Length of each coil, with short pieces grouped by gauge
• Print on the green jacket, including any wet rating
• Jumpers and lugged assemblies kept out of the coil pile