How to choose wires and cables？

Conductor specifications 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240 square millimeters. Uncommonly used ones include: 0.5, 0.75, 300, 400, 500 square millimeters, etc.  2.5 flat copper wire=4 flat aluminum wire. five × 4=20A plus threading 20 × For electricity of 0.8=16A, that is to say, choose 2.5 flat copper wire or 4 flat aluminum wire, which can carry a current of 16A when they are threaded through the tube. The load current value (part) of the electric wire specified in the national standard GB 4706.1-1992/1998 should be used for 5000 W electrical appliances.  Copper core wire: The cross-sectional area of copper core wire allows long-term current.  2.5 square millimeters (16A to 25A) 4 square millimeters (25A to 32A) 6 square millimeters (32A to 40A).  Aluminum core wire: The cross-sectional area of aluminum core wire allows long-term current.  2.5 square millimeters (13A to 20A) 4 square millimeters (20A to 25A) 6 square millimeters (25A to 32A).

Examples:

1. "Each computer consumes approximately 200 to 300w (approximately 1 to 1.5a) of power, so 10 computers require a 2.5 mm2 copper core wire to supply power, otherwise a fire may occur."；2. The power consumption of a large three horsepower air conditioner is about 3000w (about 14a), so a separate 2.5mm2 copper core wire is required for power supply for one air conditioner；3. The current housing incoming line is generally 4 mm2 copper wire, so the number of household appliances opened at the same time should not exceed 25a (5500 watts). It is useless for someone to replace the wires in the house with 6 mm2 copper wire, as the wires entering the meter are 4 mm2；4. In early housing (15 years ago), the incoming line was typically 2.5 square millimeters of aluminum wire, so household appliances that were turned on at the same time should not exceed 13a (2800 watts)；5. The household appliances that consume a large amount of electricity are: air conditioner 5a (1.2 horsepower), electric water heater 10a, microwave oven 4a, rice cooker 4a, dishwasher 8a, washing machine 10a with drying function, and electric water heater 4a. In fires caused by power supply, 90% of them are caused by the heating of the connectors, so all connectors must be welded. Contactors that cannot be welded must be replaced within 5 to 10 years (such as sockets, air switches, etc.).