How likely is your e-cigarette to explode?

A man in America died when his vape pen exploded, but how dangerous are e-cigarettes?
The case has made headlines around the world, and is believed to be the first death caused by vaping products in the US.  The man, Tallmadge D'Elia, died at his home in Florida when his device blew up and projected fragments into his skull. He was said to have suffered burns over 80% of his body.
But how common are these kinds of incidents?
In the UK, e-cigarettes have caused burns and fires, yet these cases are rare. Experts say the man who died was using a particular kind of vape pen, known as a mechanical mod, which is not that common in the UK.  Mechanical mods do not use inner circuitry to regulate the voltage, and most e-cigarettes have more built-in safety features. Yet even these safer products can cause burns or fires if incorrectly used.
Mark Gardiner, lead officer for product safety at the Chartered Trading Standards Institute, explains: "Enthusiasts might experiment with different batteries and e-liquids to try and get the biggest vape. This can result in people building their own systems which can generate a lot of heat and then explode.
"That said, even an unmodified product can go wrong, as can any product containing a lithium-ion battery. And if a battery fails and explodes then obviously it's an extra hazard if it's in your mouth."
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How to use e-cigarettes safely
•    Charge them only with the charger they come with
•    Don't leave them charging overnight
•    If batteries start to get hot, discard them
•    It's not a good idea to use them when charging
•    Do not modify products in any way
•    Do not use batteries if damaged, leaking or wet and dispose of them appropriately (via local refuse schemes)
•    Do not leave them plugged in once fully charged
Source: Chartered Trading Standards Institute
 
Source: BBC