While we're on the subject of electrical adventure, I'll start answering the question I was asked about resetting circuit breakers. Circuit protection is an important issue in a confined space where fuel and oxygen are readily available and where electrical power is needed for lighting, navigation, communication and control. The circuitry includes two generators, a battery, and multiple buses, so there is a lot to go wrong. As a result of this accident some people are discarding the usual rule of "reset once."
I'm not an electrical engineer and I'll try not to pretend to be one for this discussion, but here are some of the things I think I know about circuit breakers. Real electrical engineers can cringe along, and fill up the comments with useful corrections. Long-ago physics classes left me with the ability to talk about electricity in terms of voltage which is how hard the power source can push electrons through the circuit, current which is how strongly the electrons are flowing, and resistance which is how hard the the electrons have to be pushed to get through whatever is in the circuit. At this point in any discussion of electricity it is also required to mention that the convention for direction of current flow is in fact opposite to the direction of travel of the electrons. This is irrelevant, but if I don't mention it, someone else will.
The device that any given circuit exists to power is a source of resistance. The battery shoves the electrons though it and the thing responds by lighting up, moving a needle, transmitting radio waves, or whatever it does. The light bulb over my VSI requires less current than the starter motor or the hydraulic pump, and the airplane is designed with that in mind. If the light bulb suddenly starts drawing more current than it should, the electrical system gets suspicious and cuts it off, kind of like the power company does if they suspect you're running a grow-op, or the credit card company does every time I buy a thousand dollars worth of fuel in three different provinces on the same day.
The circuit breaker is the thing that cuts it off. To a pilot, a circuit breaker is a cylindrical thing a bit thinner and a bit longer than a pencil eraser. Rows of them are arranged with the circular ends towards the pilot in a breaker panel in the wall, ceiling, and/or dashboard. They all have labels underneath them, although some of the labels are illegible, ambiguous or wrong. Some are flush with the panel until they pop and some stick out a little ways so you can pull them yourself if you want to. When the breaker is in it completes the circuit. When it pops it sticks up and breaks the circuit. Hence the name. I think they work via a bimetallic strip, but there are probably multiple kinds.
There are two basic ways for electrical components to break. Either they don't let electricity go through them anymore, or they let the electricity go the wrong place. When a light bulb burns out, the filament breaks and electricity can't flow all the way through the circuit, so for the purpose of that bulb, the CB might as well be pulled. If a pilot pulls out that bulb and shoves a bulb in from the supply of spares, but gets the wrong kind, or twists it wrong, or there's a some metallic debris caught on it, it could allow the electricity to flow not in the base, through the filament and back through the tip of the base, but instead skip all that hard part about going through the filament and just race around through the metallic debris and out again. The electricity gets very excited about this shortcut. Increased current increases the temperature. Increased temperature increases resistance. I'm not sure which is the chicken and which is the egg in this resistance and current chicken coop, because I'd think at some point increased resistance would decrease the current but what do I know. When the current gets going past the limit prescribed by the designer of the circuit, the CB pops and all the instruments on that circuit are plunged into darkness. Cursing and flashlights are in order.
In that example, I would fly the airplane, turn on the cockpit light or the map light or something on a different circuit that would allow me to see the instruments, turn off the control for the suddenly darkened lights, remove the recently replaced bulb, check the breakers and reset the panel lighting one, and turn the lights back on. If the bit of metallic debris was still stuck in the socket and it did it again, I wouldn't know what had happened, so I'd continue my flight on emergency lighting and then later let some apprentice on the ground fish out the debris, look at me like I was retarded, and re-certify the system. If I did happen to look inside the socket and find the bit of steel wool that had caused the problem, I probably would even reset the circuit breaker a second time to see if I could get some lights. I'd let maintenance and other company pilots know it had happened, though.
I can remember two incidents in my career that might be termed electrical fires, although only in the sense of "where there's a burning smell and melted plastic there's fire." Neither progressed to fire extinguisher-requiring flames, nor did either trigger circuit protection. The first was a faulty fuel flow gauge that overheated enough to melt the indicator needle to a crispy brown colour and heat up the case enough to burn a knuckle on the glass and melt itself into the dashboard in less than 15 minutes. The reason the circuit protection did not act was that someone had put a two-amp fuse in the slot protecting the half-amp circuit. The other was a live but loose wire from an instrument light swinging around and striking sparks off everything it contacted inside the dashboard. The display of sparks was impressive. It visibly lit up the cockpit in broad daylight, and the smell was such that 30 minutes after shutting everything off, the guy who opened the back door of the airplane needed no further paperwork or explanation to understand that I had a legitimate reason for landing with no radios. No CB tripped, possibly because I didn't give it a chance: I followed my airplane's electrical fire emergency checklist, so turned off the master and pulled every CB in the panel as soon as I saw the sparks coming out of the panel. Fire, smoke and burning smells must be heeded in the cockpit.
That starts to segue to the accident they wanted me to discuss, but I'm hungry and I've written lots, so I'll continue this later making this week an all-electrical blogging bonanza.