In this new era, the demand for houses, construction sites, and urbanized areas is increasing. of equipment as well as the design and connection of electrical systems for electrical works from industrial to civil works, offices…

So how to choose the right wire according to the device capacity, both to save costs during the construction and installation of electrical equipment, and to ensure the transmission capacity for electrical equipment and safety for the electrical equipment. user. Let’s find out with us through this article.

The selection of electrical conductors must satisfy the following three criteria:

1. Selection of conductors according to the power supply
2. Selection of conductors according to device capacity
3. Selection of conductors according to the wiring plan

1. Selection of conductors according to the power supply

1.1 Power supply 1 phase 2 wire

Single-phase 2-wire source includes 1 phase wire and 1 neutral wire (also known as 1 hot wire and 1 cold wire). This is the most common source of electricity for houses in Vietnam today.

1.2 Power supply 1 phase 3 wire

Single-phase 3-wire power supply consists of 1 phase wire, 1 neutral wire and 1 ground wire (also known as 1 hot wire, 1 cold wire and 1 protection wire). In Vietnam today, this power source has begun to be applied in high-rise buildings, villas, buildings, hotels, places where important machinery and equipment are used or higher-class houses.

1.3 Power supply 3 phase 4 wire

3-phase 4-wire power supply includes 3 phase wires and 1 neutral wire (also known as 3 hot wires, 1 cold wire). In Vietnam today, this power source is rarely found in houses, unless the homeowner intends to use 3-phase electrical equipment.

• Power supply 3 phase 5 wire

3 phase 5 wire power supply consists of 3 phase wires 1 neutral wire and 1 protective ground wire (also known as 3 hot wires, 1 cold wire and 1 protection wire). In Vietnam today, this power source is very rare in houses, unless the homeowner intends to use 3-phase electrical equipment and has additional requirements for protective wires…

 2. Selection of conductors according to device capacity

To choose a conductor you need to know the load current to use, along with the current density allowed for each type of conductor. The following formula can be applied to approximate calculation: S=I/J, where:

• S: is the conductor cross-section, in mm²
• I: current flowing through the square cross-section, in Ampere (A)
• J: allowable current density (A/ mm²)

– Allowable current density of copper wire J~ 6A/mm²

– Allowable current density of aluminum wire J~ 4.5 A/mm²

For example: A 3-phase electrical device with a capacity of 10 kW we have:

– The total current is: I = P / U = 10000 / 380 = 26.3 A

– The conductor cross-section is S = 26.3 / 6 = 4.4 mm²

So we need to choose a conductor with a cross section of 5mm².

3. Selection of conductors according to the wiring plan

3.1 Floating wiring:

  Electric wires & cables are threaded in plastic pipes or plastic clips and fixed on walls and ceilings. The number of wires in the pipe should be considered so that it is not too tight to be able to pull out and thread the wire when it is necessary to repair or replace. Wire types like VCm, VCmd, VC are suitable for floating wiring.

3.2 Wiring in wall, ceiling, floor:

Electric wires & cables are threaded in plastic pipes (smooth pipes when going straight, chicken intestine pipes when turning) placed in walls, ceilings or floors. The number of wires in the pipe should be considered so that it is not too tight to be able to pull out and thread the wire when it is necessary to repair or replace. Wire types such as VC, CV, CVV, CXV are suitable for negative wiring.

3.3 Underground wiring:

For peripheral works, not attached to the house, electric wires & cables are threaded in hard plastic pipes or bearing steel pipes, waterproof and buried underground at a depth of about 0.7m. Armored or metal-clad cables can be buried directly in the ground without conduit. It is necessary to choose wires/cables that are waterproof and insect-proof for underground lines such as CXV, DSTA.

The above is a basic guide to help customers choose the right power cable. With 15 years of experience in design, construction and installation of wastewater treatment and clean water systems, VESA is completely confident in the shared knowledge. If customers have difficulty in choosing electrical cables or need design advice and quotes for wastewater treatment and clean water systems, please contact hotline (+84) 904 571 488. Best Regards./.