> The circuit it is part of is protected against overload, and WILL NOT deliver more than the rated breaker output for more than a few cycles. Actually it will

> The circuit it is part of is protected against overload, and WILL NOT deliver more than the rated breaker output for more than a few cycles. Actually it will, and it is required to do so. There are different classes of fuse and circuit breaker. The time to break the circuit depends on the class and the percentage overload, but think in terms of seconds to minutes, not cycles. The rationale for this is: A) With modern PVC insulation, the limit on continuous current is the continuous temperature. If it is too high, the wire core will slowly migrate through the PVC. Anything up to 90℃ is ok (British standards - and yes, I did check that!). Higher temperatures are ok for short periods because there will not be time for migration, but obviously you don't want to run it hot enough to cause fire ok allow fast migration. B) Electrical motors can have high inrush current when they start, but only for short periods. It makes more sense to dimension the wiring for the steady state, and use a show blow fuse or circuit breaker to guard against stall conditions. Still, the analogy is a good one. A few years ago I built a garage and had to have a Part P inspection done on the wiring, which included showing calculations which take account of the thermal environment (in free air, on wall, in tube with/without other cables etc.) and cable type to determine the maximum permitted current for that circuit. There was no "consenting adult" exception (although our legislation expressly permits non-professionals to do the job subject to Part P inspection).