About technical terms in Electric document

[AUTOMOON]

When applied, they shall be in addition to an underlying shield, which is required to ensure a satisfactory concentric conducting path for insulation charging and leakage current, as well as neutral current, phase unbalance current, fault current, and surge current.

1. which refers to underlying shield?
2, "insulation charging and leakage current" should be divided as "(insulation charging) and (leakage current)"? or "(insulation charging and leakage) current"? or else?

[probus]

When applied, they shall be in addition to an underlying shield, which is required to ensure a satisfactory concentric conducting path for insulation charging and leakage current, as well as neutral current, phase unbalance current, fault current, and surge current.

1. which refers to underlying shield?
2, "insulation charging and leakage current" should be divided as "(insulation charging) and (leakage current)"? or "(insulation charging and leakage) current"? or else?

"Which" refers to the underlying shield.

This source
Archives - Insulation Testing - Cat® Electric Power Advisor
shows that "insulation charging current" and "insulation leakage current" are two distinct phenomena.