You need to look at the regulations that apply in your country. If in doubt, use a neutral wire of the same size as the live wire or wires.
Use AWG # 3 gauge copper.
The type would be a three phase panelboard. If you are carrying the wye neutral into the service, then it would be a three phase four wire distribution panelboard. Regardless of the style used, it would have to have a minimum 400 amp bus.
Depends on the size of the sub-panel in that garage. If you are installing a 60 amp sub-panel 400 feet away from the main service panel then use AWG # 4.
For a 400 amp service entrance, a grounding conductor of at least 3/0 AWG (American Wire Gauge) copper or 250 kcal (thousand circular mils) aluminum is required, in compliance with electrical codes and regulations. However, specific requirements may vary based on local codes and the specific conditions of the installation, so it's important to consult with a qualified electrician or refer to the applicable building codes for precise guidance.
Presuming that you would like the least expensive installation, the following is calculated on overhead aluminum wire. The wire size needed to hold the voltage drop to 3% would be 3/0 MCM. If the installation could be run on 240 volts then the wire size can be reduced to #2.
Need to know what size service is going to be installed at the end of the run.
It depends on the length of the run
The size of wire for service entrance conductors for a 400 amp 3 phase service could be 500 MCM copper. This is very large size wire and difficult to bend and shape, to connect to terminals in the main disconnect and distribution panel. This problem is solved by using parallel conductors or on higher ampacities triple conductors. Using parallel conductors the wire size would be three ought (3/0) copper.
The type would be a three phase panelboard. If you are carrying the wye neutral into the service, then it would be a three phase four wire distribution panelboard. Regardless of the style used, it would have to have a minimum 400 amp bus.
Depends on the size of the sub-panel in that garage. If you are installing a 60 amp sub-panel 400 feet away from the main service panel then use AWG # 4.
For a 400 amp service entrance, a grounding conductor of at least 3/0 AWG (American Wire Gauge) copper or 250 kcal (thousand circular mils) aluminum is required, in compliance with electrical codes and regulations. However, specific requirements may vary based on local codes and the specific conditions of the installation, so it's important to consult with a qualified electrician or refer to the applicable building codes for precise guidance.
400 volt three phase on a grounded system is 230 volt single phase, with each phase 120 degrees apart. So, if you have a 400 volt, three phase four wire service (grounded service), you can pull one phase off and reference to the neutral for 230 volt service. Note this may not allow 115 volt service, unless there is also a center tap for each phase.
4 inch rigid conduit
Presuming that you would like the least expensive installation, the following is calculated on overhead aluminum wire. The wire size needed to hold the voltage drop to 3% would be 3/0 MCM. If the installation could be run on 240 volts then the wire size can be reduced to #2.
The wire size used in a service entrance distribution panel is governed by the size of the services over current device. The larger the service, the larger the fault current could be, the larger the ground wire to carry the fault current to ground. If the largest service conductor carries 100 amps use a #8, 200 amps - #6, 400 amps - #3, 600 amps - #1, 800 amps - 1/0 and over 800 amps - 2/0 for the ground wire. <<>> Golden Valley Electric Assoc. in Alaska requires #4AWG copper wire for a ground from the breaker box to earth ground rod. The same goes from the service entrance panel on the pole.
Need to know what size service is going to be installed at the end of the run.
4 inch rigid conduit
A 500 MCM wire with an insulation factor of 90 degrees C is rated at 430. Most 400 amp services will use parallel wires on each leg to feed the circuit. A 3/0 wire with an insulation factor of 75 and 90 degrees C is rated at 200 and 225 amps respectively. The insulation rating of these conductors will be 600 volts.