AC180 Grounding Cable

I just received the AC180 today. The manual talks about a grounding cable (wording below). Does anyone have any recommendations on what I would need? Why wouldn’t they include this with the product?

This product must be grounded before operation.
Connect a grounding cable (recommended 14AWG (1.5mm squared) /105degC/yellow-green color) to the grounding terminal of AC180. Fasten the grounding screw (M5*10) to fix the cable.