From the "Handbook of Electronic Tables and Formulas" for American Wire Gauge:
For chassis wiring (in air, not in a bundle): AWG #29 or larger.
For power transmission: AWG #21 or larger.
For service sizes of 100 amps and less a #8 bare copper conductor is required.
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.
This answer is taken from the CEC. Table 17 states minimum size of grounding conductors. For a service conductor drawing 400 amps a #3 copper grounding conductor is needed. Also see rules 10-206, 10-700 and 10-812 if you have access to the code book.
No, the resistance of a copper conductor does not vary according to applied voltage. It is constant for a given wire size, and only varies with temperature. Of course, current through a conductor causes it to heat, so current, not voltage, indirectlycauses a change in resistance.
The minimum size wire that can be paralleled together stated in the electrical code book is a #3 copper conductor.
#10 copper
The equivalent mm2 cross-sectional area of a 5.26 mm2 conductor is a # 10 AWG conductor. A # 10 AWG conductor size is protected by a 30 amp fuse.
Answer for USA, Canada and countries running a 60 Hertz supply service.CEC states that a #3 bare copper conductor is a common grounding conductor size for a 200 amp service panel and it is the minium size for service raceway and service equipment of 400 amps.
A #14 copper conductor is rated for 15 amps. A #12 copper conductor is rated for 20 amps.
A #1 copper conductor with an insulation rating of 90 degrees C is rated at 145 amps.
A 3/0 copper conductor with an insulation factor of 90 degrees C is rated at 225 amps.
For a typical use it would be 1/0 (one ought) wire in copper.
A 2/0 copper conductor with an insulation factor of 90 degrees C is rated at 185 amps. A motor feeder by code has to be 125% greater than the motors full load amperage. Therefore 175 x 125% = 218 amps. A 4/0 copper conductor with an insulation factor of 90 degrees C is rated at 235 amps.
A #14 copper conductor will do very nicely for this type of project.
A # 14 copper conductor will be fine to carry 8 amps at 120 volts. This size conductor is rated at 15 amps.
For service sizes of 100 amps and less a #8 bare copper conductor is required.
A 100 amp residential service requires a size #8 copper wire, it should be insulated in green.