A covered conductor line must be treated as live until it is isolated, tested dead and earthed, exactly like a bare line. The covering is not rated insulation, and it does not make the line safe to touch.
The practical difference is that standard portable earth clamps cannot make contact through the XLPE covering. Covered conductor lines are therefore fitted with dedicated earthing points at planned locations, such as either side of a switch, at section poles and at work zones that crews use regularly. These provide a bare contact surface for the earth clamp while keeping the rest of the conductor covered. Stripping the covering on site for each job should be avoided, because every stripped point becomes a weak spot.
Earthing point positions are best decided at the design stage. The MVCC tender specification checklist and the covered conductor page cover line design and accessories.