Apple could design in a "crow bar" safety device. All they would have to do is place a Zener diode across the power input pins so that if the incoming voltage is about some threshold (say, maybe 15 volts) the zener conducts and draws a LOT of current and blows a micro-sized fuse that is directly connected to the power input pin. This would work if the cable had a working ground.
The issue is the charger is still supplying 5 volts between its +ve and -ve pins, so as far as the phone is concerned all is fine and dandy. If one of those pins somehow becomes attached to either the mains live or neutral inside the charger, the whole phone is at the potential of the mains power line. BUT, the phone
will still function and charge normally since the voltage between the +ve and -ve pins is still 5v; whilst the voltage between the phone's case and ground could be 240v.
A crowbar circuit works by shorting a circuit completely (i.e. shutting it down to ~zero volts) when the voltage is too high, whereas a zener limits the voltage to the zener voltage of the diode, but the circuit doesn't shut down.
If a crowbar circuit was used in an iPhone, even fusing/crowbaring all the lines from the charger wouldn't prevent electrocution. This is because the whole phone becomes the same voltage as the mains, and there's no reference to ground. The reference that's supposed to ground (the case of the phone, the shielding in the USB cable and the USB socket in the charger) is no longer a zero volt reference due to the faulty charger. That is until some unfortunate/cheap individual provides that reference, blowing themselves up in the process. Even when someone's been electrocuted by the phone, it usually still works as the voltages inside the phone haven't exceeded the 5v limit. The phone never "sees" the mains voltage, so it can't guard against it.
In other words, it's impossible to determine the voltage of the phone's case vs ground from inside the phone, and as such, a crowbar circuit wouldn't work.
When I hear stuff like this I wonder if it's me mollycoddling my cables or if others are being careless with their equipment.
I started with the 3G, went to the 3GS and 4 and now have a 5S - all cables fine. In all that time my partners cable for her iP4 just started to fray after two years.
I take good care of my iPhone cables, but they're junk. The non-PVC "eco friendly" plastic in the cables Apple now use is actually foam, if you look at it under a magnifying glass or microscope you can see the miniature bubbles. It's very weak and poor quality. The lack of decent strain relief doesn't help either. I guess Greenpeace think it's better to drive 20 miles to the Apple store a few times a year and have 3 new eco-friendly cables than have one PVC one that lasts for years. I've got several of the older PVC ones with squeeze-to-release dock connector and they look like the day they were made.
Look around. Every house should have 5V DC power lines to begin with. Instead of a USB charger on every firkin' wall outlet, just put a beefier version in the switchboards. What is this, 1995?
Nope, that won't work due to losses in the power lines. 50 feet of cable between the switchboard and a few iPhones plugged in results in a 30% power drop, leaving just 3.5v.
Even if Apple can blame these occurances on third party adapters, if Apple doesn't start implementing a circuit breaker or surge protector in the iPhone itself to protect the iPhone from transmitting the surge, then I am going to start blaming Apple for continuing the problem.
When Apple can defy physics, they really will be magical. The iPhone doesn't transmit the surge, the charger does. You put cheap brake pads on your car and then crash into a wall, do you blame the car manufacturer who should have added some kind of extra protection incase you do install cheap pads?
It's the amps that kill you
Yes, but since the voltage in the iPhone battery is so low, there's way too much resistance in your skin to cause a short. Plus touching one terminal of a battery and the Earth at the same time doesn't provide a full circuit, unlike touching the live on a mains socket and the Earth.
