Re: A4 alternator?
"I think it's a relevant question to ask why can the sparks generated by an alternator be so dangerous while the Ingniton system is way more prone to issue sparks in the engine room... "
An alternator routinely makes sparks as the copper rings rotate under the graphite contacts. The sparks are normal. And that's why conventional alternators have wire screens (called "ignition protection" or "spark protection") installed over all air gaps, in the theory that the fine metal mesh will extinguish any flame front from the vapors getting to the spark.
On the other hand, an ignition system in proper working order DOES NOT routinely make any sparks. It conducts the ignition pulses 100% through the conductor in the wire, from the coil to the plugs, and there is never any sparking except inside the engine, or inside the distributor where the rotor and cap are also routinely sparking--but in a sealed enclosure.
It can be damned hard to make fuel combust, or explode. If you've ever tried to get an engine going and it wouldn't start, that's proof of how hard it can be to make the damned fuel explode as it is intended to.
Of course if you've ever spent time in a burn ward, where they put victims in a coma because even morphine cannot blot out the pain from extensive burns, you develop a whole new respect for the concept of explosions and flammable liquids. There are some places you never want to be. A bed in a burn ward is real close to the top of that list.