Circuit breakers are unsuitable for protecting against long-term (near-)overloads, depending on circuit breaker rating they reliably trip only at overcurrents several times their rated current (with two times the rated current being the lowest and quite rare rating). I&#x27;ve seen three phase 25A circuit breaker catch fire from being run at slight overload for few weeks.<p>For home&#x2F;office installations in 230V systems, almost any dead short is enough to trip circuit breaker (and probably several of them in the current path), regardless of wire cross sections involved, as the fault loop impedance will still be small enough to cause &gt;100A of fault current.<p>Common cords with CEE 7&#x2F;7 plug on one end and IEC C13 on the other have 0.75mm^2 conductors, which seems to be sufficient for the 10A&#x2F;70C rating. Two wire lamp cords (and Europlug-&gt;C7 cables) are also 0.75m^2. Normal three wire extension cords are 1.0mm^2 or 1.5mm^2 depending on length and (trustworthiness of) manufacturer. Recently, there are also two wire extension cords (CEE 7&#x2F;17 -&gt; CEE 7&#x2F;17 &quot;socket&quot; for things like lawnmowers and Europlug -&gt; Europlug socket for who knows what), these usually are 0.75mm^2.<p>In Czech republic, copper wiring in walls for sockets and lighting tends to be almost universally 1.5mm^2 with 2.5mm^2 used for long runs or industrial installations. It&#x27;s my understanding that current Czech wiring standards essentially removed any ampacity-&gt;crosssection tables and derating factors and only specify allowed resistance of the wire run and it&#x27;s temperature rise under load. I assume that something similar is also true across rest of the EU.