Just before the New Year, Fox News reported that an iPhone 6 Plus allegedly caught fire while it was charging. Now this isn't the first such report that I've come across, but when I looked at the images something struck me - how ratty looking the charging cable was.
Here's a screen grab of the image in question.
Now before you all jump into the comments section to tell me how rubbish Apple's Lightning cables are, save yourself the typing. I know. I'm lucky if a genuine Apple cable lasts me a year before it starts to fray at the end. They're embarrassingly bad.
They're by far the worst product that Apple puts its name to.
But once they're frayed, they're potentially dangerous. An iPhone charger puts out 5 volts at 5 watts/1 amp (an iPad charger puts out 12 watts/2.1 amps), and while that doesn't sound like much, it's more than enough power to cause overheating and the beginnings of a fire. On top of that, a frayed cable can also cook the battery by causing a short circuit, which again can result in a fire.
Apple recommends that you charge its devices using genuine Apple chargers and cables. If you're going to replace old charger or cables, do so with either a genuine Apple part or a decent third-party product (preferably one featuring the "Made for iPhone" logo).
I can't comment on whether the cable had anything to do with the fire in the report, but I certainly would not use a cable in that state. I have repaired cables that have started to break, but in my experience that only buys you a few months before the cable breaks again. The safest thing to do is to replace any damaged cables.