There is no one wire that is rated for 1800 amps. The service will have to be a quad parallel of the conductors. A 600 MCM conductor with an insulation factor of 90 degrees C is rated at 475 amps. This conductor paralleled into four equal lengths will give an ampacity of 1900 amps for each leg of the service.
As a service entrance wire you need AWG # 3/0 gauge copper.
#6 bare copper wire.
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.
Service entrance wire should be AWG #3 copper.
2 copper
As a service entrance wire you need AWG # 3/0 gauge copper.
#6 bare copper wire.
200 amp service in chicago uses 3 aught.
It depends on the length of the run
To calculate the wire size, a system voltage is needed.
This is a voltage drop question. To receive an answer to this question the voltage of the service must be stated.
From the question it is hard to establish whether the service size is 350 amps or the service conductors are 350 MCM in parallel. If the service is 350 amps, the grounding conductor is #3 bare copper wire. Parallel 350 MCM conductors will allow for a 600 amp service. The grounding conductor for a 600 amp service is a #1 bare copper wire.
4 sets of 750 mcm aluminum. Or four parallel runs of 600 MCM copper.
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.
# 6 copper wire.
This can't be answered without knowing the voltage, and ground is not the same as neutral, in AC circuits, which I'm assuming this is.
To answer this question the voltage and load amperage is needed.