This isn't an iPhone we're talking about, this is the charger which is connected to 220V AC power. The chargers are build very small, and cheap off-brand chargers have insufficient clearance between the LV and the HV side. This is dangerous, and can cause the 220V mains to go through to the USB port. This is also a very well-known property of cheap phone chargers, and you can find many teardowns online that show what I'm talking about. [this video] [link] [link] I have also seen a few videos of teardowns of actual faulty chargers. For example, there was one where some of the insulation in the transformer windings were damaged, and you would get a continuous shock just by touching the LV side of any devices that are plugged in.
Teardown evidence of cheap chargers lacking mains isolation clearance.
Right, and the charger is plugged into the wall which provides 220VAC. The cheap chargers are unsafe because they don't have enough clearance between the high voltage and low voltage sides of the circuit, so the isolation can fail and energize the USB port with 220VAC, for example. This is a well-known failure mode of cheap phone chargers, and it should be obvious why these shortcuts are illegal in most countries. Teardowns of cheap USB chargers online explain what I'm talking about, for example, [this video]
Example teardown showing unsafe isolation in cheap chargers.
There's been multiple reports of people dying through headphones. Maybe they're all bogus, but considering an ER doctor presumably knows nothing about electronics, I'll disregard his opinion. Instead I'll listen to what an electronics engineer thinks about counterfeit chargers: [this video]
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