Earthing (Grounding) neutral terminals in transformer and converter
Normally inverter outputs float and are not directly grounded. Even though it floats relative to Earth ground, touching pins 3 and 4 at the same time will cause a nasty shock and burn. Hard grounding pin 4 after the diodes means touching just any pin 3 will cause a bad shock.
For this reason grounding is often done using 1 M ohm resistors rated for twice the line voltage, or 2 470 K ohm 1/2 watt metal film resistors in series, which would have a 800 volt rating. Sometimes a 3 KV disc capacitor of 1 nF to 5 nF is in parallel with the resistors to ground RF noise.
The resistors offer a static ground so output has at least a high impedance reference to Earth ground. The resistors limit &quot;shock&quot; current to a safe level. You may feel a mild shock but it has a million times less current to hurt you with. This is about as far as you can safely take this grounding issue.