Electrical Cable Sizing: Calculation Guide

Electrical Cable Sizing: Section Calculation Guide with Table

Importance of Correct Sizing for Domestic Systems

If you are designing or renovating your home's electrical system, it is essential to select the correct section of electrical cables. This process allows you to guarantee not only the efficiency of the system, but also and above all the safety of people and the home itself. The choice of cable section depends on many factors, including the type of device to be connected and the maximum current it must withstand.

Tips for Choosing the Cable Section

• Section 0.5mm²: This section is suitable for home alarm burglar alarm systems or for connecting intercoms and video intercoms. It is important not to use this section if the voltage is equal to or greater than 230V.
• 10A: For lighting circuits or other devices up to 10A, we recommend using cables with a 1.5mm² section.
• 16A: For sockets and switches up to 16A, as well as for household appliances such as oven, washing machine, dishwasher, it is advisable to use cables of at least 2.5 mm².
• 25A: If the device has circuits with currents higher than 16A, for example induction hobs, cables with a section of at least 4mm² must be used.
• 32A: For some induction hobs with currents equal to or greater than 32A, it is necessary to use cables with a section of at least 6mm².

In-depth analysis of Electrical Cable Sections and Colors

Following the in-depth analysis on the colors of the electrical cables regarding the phase, neutral and earth, it is important to discuss the sizing and calculation of the section. This step is crucial to ensure you choose the most suitable cable, depending on the different applications and loads to be supported.

Table of Cable Sections Available on the Market

Below is a summary table of the most common sections (expressed in square mm of the copper wires that make up the cable) that can be found commercially available:

• 1.5 mm²
• 2.5 mm²
• 4 mm²
• 6 mm²
• 10 mm²
• 16 mm²
• 25 mm²
• 35 mm²

Each section has its own usage specifications, and choosing the right one is a fundamental decision. Compliance with current regulations and the advice of a qualified technician can help avoid risks and create a safe and efficient system.

Importance of Calculation in the Dimension of Electrical Cables

The calculation process is fundamental when it comes to designing an electrical system. One of the main reasons is the need to determine the appropriate number of copper wires in a cable to accommodate the passage of electrical current. The number of wires directly influences the cable cross-section , which is a key factor in managing energy efficiency.

Benefits of a Major Section

A larger cable cross-section brings significant benefits, including:

• An increase in the amount of current that can flow through the power line, thus reducing energy losses during transportation.
• The reduction of internal resistance, which translates into less heat generation and, consequently, a lower risk of overheating of the cables.
• An improvement in energy efficiency , allowing you to optimize energy consumption and reduce operating costs.

Risk Prevention

It is essential to carry out the right calculation already during the design phase to prevent problems such as:

• Short circuits and fires , which can result from overheating of cables due to inadequate cross-sections.
• The phenomenon of the Joule effect , which generates excessive heat if the cable section is not proportionate to the required current flow.
• Increased CO2 production , which negatively affects the climate due to increased energy demand due to transmission losses.

In conclusion, an adequate calculation of the section of electrical cables is imperative to guarantee not only the safety and efficiency of electrical systems, but also to limit the environmental impact linked to the use of electricity.

How to Calculate the Correct Section of Electrical Cables?

Optimal cable sizing is essential to ensure the efficiency and safety of electrical systems. There are two basic methods for calculating the appropriate section:

• Range Method

  It is based on the maximum current tolerated by the cable. This method allows you to size the appropriate section depending on the use of the system, whether it is single-phase or three-phase.

• Maximum Allowable Voltage Drop Method

  After having defined the section using the range method, a check is necessary by calculating the voltage drop, to ensure that the maximum permitted values are not exceeded.

A key aspect is that both criteria must be met. While the flow rate method identifies the right section for the field of application of the system, the voltage drop method serves to validate the choice.

Sizing for Standard Power Lines and Long Lines

In the case of power lines with standard lengths, such as those of civil systems, voltage drops are negligible. The focus of the sizing is on the cable capacity, based on the maximum expected current.

However, for long power lines, you also need to consider the voltage drop that may occur. Once calculated, it is checked with the carrying capacity method whether the current flowing through the conductor is within the carrying capacity of the cable.

Electrical Cable Sizing Strategies

Sizing with Voltage Drop

• Calculate the power of the current in your electrical system.
• Estimate the maximum allowable voltage drop to determine the appropriate cable section.
• Verify that the calculated voltage drop does not exceed the maximum limit. If necessary, increase the cable section.

Sizing with Flow Rate

• Analyze the strength of the current in the power line and the technical details related to the cable.
• Select a section that has a slightly higher flow rate than the expected current.
• Carry out a check of the scope of the chosen section. If less, increase the section until adequate capacity is reached.