Permitted Output Power 2.5mm2 Cable: Analyzing Insulation & Temperature for 20A-30A Current Flow

Hello.

I have calculated that I can expect a 2.5mm2 separation of about 4W power on 1 meter of copper conductor when 20A current flows. For 30A it will already be about 9W of power.

Well, for such a 1 meter cable in the wall when it flows permanently around 22A (let's assume 5W power) can I expect cable insulation to burn out and damage? The cable is 5x2.5mm2.

I also wonder if the cable placed in the wall, stuck with plaster, gets much warmer compared to the cable loosely laid outside the wall.

1. By overloading the wire / cable for longer than its normal operating temperature, you shorten the life of the insulation.
2. Load capacity of wires / cables - 2.5mm2 you protect 16A higher currents means larger cross-sections and protections.
3. There are special load capacity tables provided by the wire / cable manufacturers depending on the arrangement.

I suggest you familiarize yourself with: A few words about the protection of installations, motors, and RCDs

The long-lasting current for 2.5mm2 is under the link like 24A, I also met with the value of 25A so it seems possible to protect it with 20A.

I wonder how heating cables depends on their location.

bartosz.tarnowski wrote:

I have calculated that I can expect a 2.5mm2 copper conductor section of 1meter about 4W when a 20A current flows.

Not 4W but 6-7W.

bartosz.tarnowski wrote:

I also wonder if the cable placed in the wall, stuck with plaster, gets much warmer compared to the cable loosely laid outside the wall.

What do you think ?
The physicist will answer this question.

Finally, I overlooked the fact that the long-term current for a 5x2.5mm2 cable is smaller than for a 3x2.5mm cable.
Estimating the heating of the cable, I wanted to avoid having to replace it with a thicker cable, but unfortunately I had to do it.