--- title: "Plug in one prong set and this adapter's other prongs go live" locale: "en" url: "https://irz.fr/en/articles/lethal-universal-travel-adapter-en" markdown_url: "https://irz.fr/en/articles/lethal-universal-travel-adapter-en.md" category: "tech" tags: ["electrical", "safety", "adapter", "travel", "teardown", "mains"] published_at: "2026-09-03T08:00:00.000Z" author: "Léa Perrin" translation: "https://irz.fr/fr/articles/adaptateur-universel-broches-vivantes-fr.md" --- # Plug in one prong set and this adapter's other prongs go live A nine-dollar universal travel adapter bus-bars every set of prongs onto one conductor. Plug in one set and the others sit at mains voltage. A "universal" travel adapter is built on a simple idea: any device, any outlet, anywhere. `Brainiac75` bought one for nine dollars and took it apart. What he found sits squarely inside a familiar category of failure, the one where an object chases maximum compatibility at the lowest price and ends up with exposed mains contacts nobody should ever handle.[1](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) He paid **$9.26**. Inside the box sit three sets of sliding prongs, American, British and European, with two USB ports on the side. As soon as one set is plugged into a live socket, the other two carry the same mains voltage.[1](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) The spare pins are getting real power, not a phantom. ## The shared bar A resistance check settles the question. The unused prongs connect to the very same conductors as the set doing the work.[2](https://www.techeblog.com/dangerous-travel-adapter/) Open the case in the teardown video and the layout comes into view: each extended prong set presses onto contacts that feed **a single shared bus bar**.[3](https://www.youtube.com/watch?v=M_xfz1oyxHw) It costs almost nothing to build that way, which is the point.[1](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) Notably, the design never insists on one prong set at a time. Several can stay out, and nothing separates the rest while a single set is connected.[2](https://www.techeblog.com/dangerous-travel-adapter/) ## Retracted does not mean cut Retraction is meant to be the safety valve. Push a set all the way back into the case and it stops being live, full stop.[1](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) The mechanism just never demands it. Walk away with the American or British pins still sticking out and they stay hot while the European plug is in the wall.[2](https://www.techeblog.com/dangerous-travel-adapter/) Add a shared bar to that and there's your danger in full effect. It shows up in real use, not just on a bench. `Brainiac75` took the sensible way out. He removed the American and British sets, taped over the openings, and the box becomes a plain USB charger with a universal mains port. That suits the thing better than travelling with it as an adapter.[1](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) > **Why everything goes live** > - All three prong sets meet at one central conductor.: Shared bar > - Deploying a set closes the contact with the bar.: Extended = contact > - No interlock isolates the sets left extended.: Nothing cuts it > - Any extended prong carries full mains voltage.: Mains everywhere > Flaw exposed by Brainiac75's teardown, corroborated by Hackaday and TechEBlog. ## The USB side The two USB ports come off better than the rest. The label promises 5 V at 2.1 A. Under load the output climbed toward **2.4 A before turning unstable**, with no hard cut-off beyond that.[2](https://www.techeblog.com/dangerous-travel-adapter/) It skips any modern charging protocols and the regulation stays loose, yet none of that is dangerous like the shared bar. The little red power light still glows briefly after you pull the box from the wall. That is the capacitors draining, and the pins settle back to a safe level soon enough.[2](https://www.techeblog.com/dangerous-travel-adapter/) ## What the flaw teaches Ditch every interlock to reach a low price and total universality and you trade a protective element for a bunch of parallel contacts. A protective element only engages when a condition is met; parallel contacts just stay connected.[2](https://www.techeblog.com/dangerous-travel-adapter/) Safety then leans entirely on the user remembering to be careful, which is a thin substitute. Adapters that expose one prong set at a time do exist. That difference is a design choice, unrelated to price. For this nine-dollar example, the real takeaway is simpler: a continuity check and a look inside are plenty to spot a hazard before it travels with you. ## References 1. [Hackaday, Dissecting A Lethal Universal Travel Adapter, August 30, 2026](https://hackaday.com/2026/08/30/dissecting-a-lethal-universal-travel-adapter/) 2. [TechEBlog, Slightly Dangerous $9 Travel Adapter Boasts a Shared Bus Bar, and Live Extra Pins, August 30, 2026](https://www.techeblog.com/dangerous-travel-adapter/) 3. [Brainiac75, SHOCKING TRAVEL ADAPTER! Mains Voltage Exposed, USB Output Test (YouTube)](https://www.youtube.com/watch?v=M_xfz1oyxHw)