Typically residential and many commercial applications use a 15 amp service for lighting circuits. They use 14 AWG wire.
Usually 15A or 20A, but it depends on the wire used.
No, you can never mix wire sizes in a circuit.
Number 14 for lighting circuits, Number 12 for convenience outlets, and Number 10 for certain large or motorized appliances.
A new outlet (running new wire) or replacing an old one (wires already there)? Shut off the Power to that Receptical, diconnect the receptical, and reconnect the New receptical using the Wires from the one you replaced. Then turn the power back on and Test it with a Tester!
Wire sizing is dependant upon the loads connected. In North America home wiring consists of #14 for lighting and branch circuits. Larger size wire for dedicated circuits (example hot water tank) will use #12, For clothes dryer #10, and for range #8. If the home has a shop #6 for a welder plug. As you can see there are many sizes of wire that are needed to completely wire a home.
Yes, the feeder will have to be a three wire cable.
There are two circuits on the battery and motor. One wire is take which have four ends. The wire is connected on the desired circuits.
An engineered set of blueprints will have all of the pertinent information about circuit loading and circuit numbers and panel balancing already calculated. If there is no wiring schedule on the print then you refer to the electrical code book and abide by the regulations that are set out for circuit loading and the amount of devices that can be connected to that circuit. Single family dwelling: multiply the number of square feet by 3. So a 2500 sq ft home times 3 = 7500 watts. Divide that number by 1500 for #14 wire circuits or 2000 for #12 wire circuits. 7500 divided by 1500 = 5 #14 wire circuits or if divided by 2000 + 3.75 or 4 #12 wire circuits. This would be for the lighting load and general use receptacles through out the home. I always lay my circuits out where a circuit only covers 500 sq ft of the dwelling.
A typical three prong residential outlet for 120 volts has a brass colored, a silver colored and a green screw. Connect black wire to brass, white wire to silver and bare ground wire to green.
The most common wire ran in 120v residential is NM (Non-metallic) sheathed wire such as the brand Romex. 14 gauge wire generally has a white sheathing and can be used on 15 amp circuits such as lighting. 12 gauge wire is thicker, generally having a yellow sheathing and can be used on 20 amp circuits such as those serving receptacles. Considering future demands, 12 gauge wire should be used. Under no circumstances should you ever use 14 gauge wire on a 20 amp circuit.
It is used as a hot wire. <<>> In a three conductor cable set the third wire colour is red. In home wiring a three wire cable is used in a couple of locations. If the circuit involves a three way switching circuit, the cable between the two light junction boxes is fed with a three wire cable. Check the Internet for three way lighting connections. The other location a three wire cable is used is in split circuitry. Your kitchen counter receptacles use this method of wiring. The tie bar in the receptacle is removed on the hot (brass colour) side of the receptacle and the red wire is connected to the top brass screw and the black wire is then connected to the bottom brass screw of the receptacle. The white wire, as always, is connected to the silver coloured screw of the receptacle. Another example of using a three wire cable is to take two circuits from the distribution panel to two separate circuits on the other side of the house instead of running two, two wire circuits. The three wire cable is terminated in a junction box and two two wire circuits are feed from this junction box to the circuits that require power. The two two wire circuits will use the white wire of the three wire cable as a common neutral.