I was goaded into joining this forum by a fellow Trekker after I explained to him in extreme detail how surge-protectors and insulator devices fail under heavy loads. I used the example of the Exploding Consoles Of Doom from Star Trek to make my point.
The insulator devices I manufacture have a certain rating that we call the flashover rating. On paper we need to maintain a specific sized gap between the power line and the support structure. This way a surge induced by lightening or a transformer switching error won't jump from the line to the pole. If that happens, the surge can damage other devices like telecommunication devices, switches, street-lamps... and in extreme cases it can destroy the support structure.
We're talking about ratings of up to 35,000 volts during "normal operation..." During a lightening-induced surge the the voltage can increase to well over 300,000 volts.
Our product is designed to prevent an arc from forming, and if it does it is deigned to burn away forming a quenching and non-conductive gas that immediately arrests the arc.
What you are seeing when a console explodes is the failure of the insulators and surge protectors. Just like the product I work with, Starfleet Issue Protective Isolators would have a maximum rating.
During combat, lets face it... both sides are slinging massive amounts of power around trying to make the opposing side explode. Eventually one or more isolators are going to be overwhelmed and an arc is going to jump between the power-carrying components of the ship and the frame... and all that power has to go somewhere.
Sometimes it dissipates harmlessly, other times it causes things to fail catastrophically. Frankly given the power levels we are talking about I'm surprised there aren't more internal explosions.
Now for whatever reason nameless guest-extras seem to attract these surges... I am trying to isolate this property and incorporate it in our Generation IV design. I think it has more to do with blood-thirsty writers, Screen Actor Guild contracts and the VFX department more than any physical property.... however testing is ongoing as I speak.