The Type G plug is the chunky three-blade block familiar across the United Kingdom, Ireland, Malta, Cyprus, Singapore, Hong Kong and Malaysia, and it is defined by the British standard BS 1363. Among the world's common plugs it is the odd one out in a way that matters, because it is the only one that carries its own fuse inside its body. Pop open the casing and there sits a small cartridge, typically rated at 3 amps for light electronics and 13 amps for heavy loads like heaters. That fuse exists for a specific reason.

British homes are wired on high-capacity ring circuits capable of delivering far more current than a thin appliance cord could safely handle, and rather than trust the circuit alone to protect every device, BS 1363 pushes the last line of defence right down into the plug. The cord is guarded at its own doorstep. The rest of the design is just as deliberate. The earth blade is longer than the two that carry the current, so it enters the socket first, and as it goes in it does a second job: it lifts a pair of internal shutters that otherwise sit closed over the line and neutral holes.

Until that long earth pin arrives, the live openings stay sealed. This is why nothing else slots into a British socket without an adapter. The shutters simply will not open for anything shaped differently. The plug is bulky, notoriously painful to step on, and unmistakable in the hand, but every part of that heft is doing work. It fuses itself, it earths itself first, and it keeps its live contacts shut until the right shape comes to open them.