This product is an intentionally grounded wire that completes a circuit if the neutral conductor fails. It’s sometimes referred to as “earth” or “earthing” wire.
A bare or insulated conductor connected to the earth to create an electrical path of resistance for the purpose of conducting electrical current back to the ground.
In the US, this conductor is usually bare copper, or insulated as green, green/yellow, or black. The most typical and cost effective weather and abrasion resistant insulations are polyvinylchloride (PVC) and high molecular weight polyethylene (HMWPE).