Knowledge sharing on current and power related to power cords
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What is the maximum current that a 1-square millimeter power cable can carry? What is the actual power level? What is the maximum current that can flow through a one-square-inch power cable? What is the actual power level? I know the total power; how large an incoming cable do I need to install? If 2.5-square millimeter wires are installed in the monitoring room, what power rating can the monitoring system handle? In one word: how to determine the size of wires and cables required during the construction of surveillance systems. Actually, there is a specialized algorithm for this, with slight variations depending on the environment. Generally, it is as follows: The operating temperature is 30°C, and the current-carrying capacity under a continuous 90% load over an extended period is as follows: 1.5 square millimeters – 14A, 2.5 square millimeters – 26A, 4 square millimeters – 32A, 6 square millimeters – 47A, 16 square millimeters – 92A, 25 square millimeters – 120A. The power corresponding to each current value is as follows: 1A = 220W, 10A = 2200W, and so on. For a copper wire with a current-carrying capacity of 14A, it is: 220W × 14 = 3080W; therefore, the power handling capacity of a 1.5-square-millimeter copper wire is 3.08 kilowatts. Maximum continuous current for copper-core wires: 2.5 square millimeters (16A–25A), 4 square millimeters (25A–32A), 6 square millimeters (32A–40A). Maximum continuous current for aluminum-core wires: 2.5 square millimeters (13A–20A), 4 square millimeters (20A–25A), 6 square millimeters (25A–32A)
There are many practical conversion formulas. I still remember them: for aluminum-core cables of different diameters, the current-carrying capacity is nine times that for a 2.5 mm diameter cable; for larger diameters, subtract one and then increase the value by one accordingly. For 3 mm and 5 mm diameter cables, multiply by 3.5. When cables come in pairs, the capacity is halved. In the case of copper-core cables, simply use the corresponding formula for aluminum-core cables and increase the value by one grade.
This kind of estimation isn’t very accurate; it’s fine to estimate when the power is quite low, but when the value is higher, a more precise calculation is necessary. The current-carrying capacity can vary significantly depending on the ambient temperature, the type of cable, and the way it is installed. Not to mention that voltage drop and sensitivity also need to be taken into account as the distance increases.