28mA is more than I expected ( I have to make a note for when I have a VFD)

by the time you add 3.5mA for the earth leakage for a PC's ATX power supply and possibly another 1 to 3 mA for the additional filter connecting the machines mains 15A supply fuses to the contactors C1 and C2 you are well over the 30 mA limit

John


Attachment 300168

example of a typical mains filter
Attachment 300170

note the two capacitors marked Y
the leakage due to the Y capacitor across live and earth is the cause of the problems
due to the symmetrical filter circuit being connected to an asymmetrical supply - the earth and neutral are connected together at the star point of the utility supply transformer

connected to the symmetrical American 220V supply terminals L1 L2 and earthed centre tap
the currents through the two Y capacitors will cancel ( assuming they are exactly the same capacitance)