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How Many Amps Can a 4mm Solar Cable Handle?

Updated: Mar 31, 2023

Amps Handling by 4mm Solar Cable

If you're building a solar power system, one of the most important considerations is the type of cable you use to connect your solar panels to your batteries or inverter.

In this blog post, we'll focus on 4mm solar cables, which are commonly used in residential and small-scale commercial solar installations. Specifically, we'll explore how to determine the ampacity rating of a 4mm solar cable and calculate its maximum current capacity.

We'll also provide some tips for minimizing factors that can affect current handling capacities, such as temperature and cable length.

What is a 4mm Solar Cable?

4mm Solar Cable manufacturer

Before we dive into the technical details of 4mm solar cables, let's first define what they are.

A 4mm solar cable is a type of electrical cable that is designed for use in solar power systems. It typically consists of multiple strands of copper or aluminum wire, which are encased in a protective jacket made of a UV-resistant and weather-resistant material such as cross-linked polyethylene (XLPE).

4mm solar cables are available in both single-core and multi-core configurations, and they may be TUV certified for safety and performance. They are commonly used to connect solar panels to charge controllers, batteries, and inverters, and they may be sold with connectors or as bare wires.

Understanding Ampacity Ratings

Now that we know what a 4mm solar cable is, let's talk about its ampacity rating. Ampacity refers to the maximum amount of electrical current that a cable can safely carry without overheating or causing damage.

4mm solar cables supplier

The ampacity rating of a 4mm solar cable is determined by several factors:

  • The size and material of the cable's conductors

  • The ambient temperature of the installation site

  • The temperature of the cable itself

For example, a 4mm solar cable with copper conductors may have an ampacity rating of 35 amps at 25°C, while the same cable with aluminum conductors may have an ampacity rating of 28 amps at 25°C.

Calculating Maximum Current for a 4mm Solar Cable

To determine the maximum current that a 4mm solar cable can handle, you'll need to consider several factors:

volts testing from 4 solar cable
  • The ampacity rating of the cable

  • The length of the cable run

  • The size of the conductors

  • The voltage of your solar power system

  • The temperature at the installation site

Here's a formula you can use to calculate the maximum current capacity of a 4mm solar cable:

  • Maximum Current (Amps) = (Ampacity Rating) x (Correction Factor for Temperature) x (Correction Factor for Conductor Size) x (Correction Factor for Voltage Drop)

For example, let's say you have a 50-foot cable run with a 12V battery and a 4mm solar cable with copper conductors and an ampacity rating of 35 amps at 25°C. The temperature at your installation site is 40°C. Using the correction factors from the National Electrical Code (NEC), we can calculate the maximum current capacity of the cable as follows:

  • Correction Factor for Temperature = 0.91 (for 40°C)

  • Correction Factor for Conductor Size = 1 (for 4mm)

  • Correction Factor for Voltage Drop = 1 (for a 12V system)

Maximum Current (Amps) = 35 x 0.91 x 1 x 1 = 31.85 amps

In this scenario, the maximum current that the 4mm solar cable can handle is 31.85 amps.

Factors That Affect Current Handling Capacity

While it's important to understand the maximum current capacity of a 4mm solar cable, it's also important to be aware of factors that can affect its performance.

Suitable Temperature for 4mm Solar Cables

For example, high temperatures can cause a cable to degrade over time and reduce its current carrying capacity.

Likewise, long cable runs can cause voltage drops, which can lead to a reduction in current capacity.

TIPS: To minimize these effects, you can

  • Choose a cable with a higher ampacity rating than you need to account for temperature and voltage drop

  • Install the cable in a shaded area to minimize exposure to direct sunlight and heat

  • Keep cable runs as short as possible

  • Use thicker conductors to reduce resistance and voltage drop

  • Install additional charge controllers or inverters to reduce the current load on a single cable

Other Considerations for 4mm Solar Cables

In addition to ampacity ratings and current handling capacity, there are a few other factors to consider when choosing and installing 4mm solar cables:

TUV Certification for 4mm Solar Cables
  • TUV certification can ensure that a cable meets safety and performance standards for solar power systems

  • UV-resistant jackets can help protect cables from damage caused by prolonged exposure to sunlight

  • Connectors and accessories can make installation and maintenance easier


Now that you understand the importance of the ampacity rating and the current handling capacity of a 4mm solar cable, you can make an informed decision when choosing the right cable for your solar power system.

At FRCABLE, we offer high-quality 4mm and other sizes of solar cables with a TUV certification. We provide cables with UV-resistant jackets, various connectors, and many others for easy installation and maintenance.

Visit our product page for more information and specifications, and contact us for a quote to get started on your solar power system project today!

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 Founded in 2007, FRCABLE is a trailblazing company in the solar photovoltaic industry, specializing in the production of high-quality cables and cross-linked cables.

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