LTspice earthing information
SPICE-like simulators like LTSpice don't make any special consideration for the earth node. If protective earth is different from the circuits reference ground, you can just define a new node and call it EARTH or PE or NODE5 or whatever you want.

Remember that current only flows in complete circuits so you will probably have to include some parasitic paths in your model for the earth connection to have any effect on the circuit behavior.