{"id":3748,"date":"2026-09-15T18:38:00","date_gmt":"2026-09-15T15:08:00","guid":{"rendered":"https:\/\/www.simrodsama.com\/?p=3748"},"modified":"2026-10-05T18:05:16","modified_gmt":"2026-10-05T14:35:16","slug":"aluminum-cable-voltage-drop","status":"publish","type":"post","link":"https:\/\/www.simrodsama.com\/en\/article\/aluminum-cable-voltage-drop\/","title":{"rendered":"Aluminum Cable Voltage Drop: Calculation & Cable Size Selection"},"content":{"rendered":"
\"Voltage
Voltage drop in aluminum cables depends on cable length, current, conductor size, and operating conditions.<\/figcaption><\/figure>\n

<\/span>Aluminum Cable Voltage Drop: Calculation and Proper Cable Size Selection<\/span><\/h1>\n

Imagine an electrical panel, motor, or industrial load located relatively far from its power source. The voltage at the beginning of the cable may be appropriate, but the voltage measured at the end of the cable, at the point of consumption, is lower.<\/p>\n

Part of this difference is known as cable voltage drop<\/strong>.<\/p>\n

An electrical conductor does not have zero resistance or impedance. When current flows through a cable, part of the voltage is lost along the cable length. Therefore, when designing an electrical circuit, it is not enough to determine whether the cable has sufficient current-carrying capacity. The voltage available at the end of the cable must also remain within an acceptable range.<\/p>\n

This issue is particularly important when using aluminum cables<\/strong>, because aluminum has higher electrical resistivity than copper. Therefore, copper and aluminum cables with the same cross-sectional area cannot simply be considered equivalent in terms of voltage drop. In approximate calculations presented in Schneider’s IEC-based guide, resistance coefficients of 37.6 \u03a9\u00b7mm\u00b2\/km for aluminum and 23.7 \u03a9\u00b7mm\u00b2\/km for copper are used.<\/p>\n

In this article, we examine how cable voltage drop is calculated, which factors increase it, and how to select the appropriate cross-sectional area for an aluminum cable.<\/p>\n

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<\/span>What Is Cable Voltage Drop?<\/span><\/h1>\n

When electric current flows through a conductor, the impedance of the conductor creates a voltage difference between the beginning and end of the cable.<\/p>\n

This difference is known as:<\/p>\n

Voltage Drop<\/strong><\/p>\n

For example, if the voltage at the beginning of a circuit is 400 volts but the voltage measured at the end of the circuit under load is 390 volts:<\/p>\n

Voltage Drop = 10 volts<\/strong><\/p>\n

The voltage-drop percentage is calculated as:<\/p>\n

Voltage Drop (%) = (Voltage Drop \u00f7 Rated Voltage) \u00d7 100<\/strong><\/p>\n

Therefore, in the example above:<\/p>\n

(10 \u00f7 400) \u00d7 100 = 2.5%<\/strong><\/p>\n

As voltage drop increases, the actual voltage available to the load moves further away from the expected voltage.<\/p>\n

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<\/span>Why Is Voltage Drop Important?<\/span><\/h1>\n

A cable may have an adequate current-carrying capacity and still not be the right choice for a particular project.<\/p>\n

For example, suppose a cable is capable of carrying 100 amps. If the same cable is installed over a very long route, the voltage drop at the end of the cable may exceed the acceptable limit.<\/p>\n

Therefore, at least two independent checks should be performed when selecting a cable:<\/p>\n