Hello Moshe:
Virtually all leakage current arises from the stray and
real capacitances between line (live) and ground (earth).
To reduce leakage current, you have two choices:
1. Reduce the capacitance.
2. Install a 1:1 isolating transformer between the mains
and the load.
2a. If the transformer is built into the equipment, the
leakage current changes to that of the primary of the
isolating transformer.
(This technique is commonly used for medical equipment
systems with high leakage current.)
2b. If the transformer is external to the equipment, then
the secondary of the transformer must be floating
(i.e., no neutral).
Here are some choices that don't reduce the leakage current,
but prevent the leakage current from becoming accessible.
3. Change to all-insulated construction so that there are
no accessible conductive parts, including low-voltage
secondary circuits. This doesn't change the leakage
current in the green/yellow wire, but it does make the
leakage current inaccessible.
4. Redundant ground connection. Some standards waive the
leakage current requirement if the equipment is installed
with a second, separate ground wire, whose connection is
permanently connected. This, likewise, assures that the
leakage current does not become accessible.
Best regards,
Rich
