Transfer Switch Switch Neutral

[GDeVine]

I am an Extra Class ham radio operator and responsible for electrical systems I set up for use in emergencies
I have a transfer switch that switches the neutral (breaks connection with house neutral) on my house.
NEC says it is a separately derived system.
I am using a portable generator and the neutral is bonded to the frame(ground).
My question is why does it need its own grounding rod? Isn't it already using the house ground?

 

[tom baker]

This is an almost duplicate of an earlier post. Portable generators for emergencies is different from wiring a genny for your house. The other mods can review this.