The silence after a blown fuse is almost eerie. The kettle cuts out, and you’re plunged into darkness, leaving only the faint hum of the radio still plugged into another socket. The shouting match to see who nips down to the fuse box first seems deafening by comparison. But that moment of quiet is really just a pause for breath, a moment to catch up with events. A few thousandths of a second before all that, something happens inside the blown fuse, invisible to the human eye. A plastic switch trips, an arc of electricity breaks, and the house plunges into darkness. All thanks to a little piece of kit called the circuit breaker. For an Electrician Cheltenham, consider www.blu-fish.co.uk/electrical-services-cheltenham/
The heat detector works much like your hand when it touches something hot and recoils in shock. The ‘hand’ of the circuit breaker is a bit of bimetallic strip made from metal bonded to metal, each expanding at different rates when warmed. Under normal conditions, when current flows unimpeded through the system, both metals expand, but there’s no issue with the current load. When the house is overloaded with appliances sucking power off the mains, however, the strip soon begins to feel the effort. As the electrical fire rages on in slow motion, the metals expand unevenly until the strip is sufficiently heated and bent. That flexes a latch holding the plastic switch together, causing it to flinch violently and snap apart. This causes the circuit to break, releasing the switch from its sustained effort. In human terms, the bimetallic strip becomes the electrical equivalent of a muscle, contracting and pulling the latch over.
If that were all it did, though, most houses would have burned down years ago. It takes too long for that to happen in a real electrical emergency. If there’s a short circuit in the wires of your house, then voltage surges into billions of amps in a fraction of a second. A bimetallic strip is far too slow at detecting this, as it would take heat far too long to have any effect. For these kinds of emergencies, a separate circuit breaker must kick in, one where the electrical emergency is countered in almost a hundredth of the time of a heat-detection system. So you don’t just rely on your reflexes but also the physics behind them.
