Mostly Cajun is a commercial electrician and occasionally writes about incidents at work. High voltage is a lot different than house current and it has its own set of rules.
Todays is a perfect example: Blowup!
Sometimes a little knowledge is a dangerous thing. Early in my career as a high voltage power systems technician I ended up in a facility which had just suffered multiple major power outages. An electrical fault had resulted in an underground 13,800 volt feeder cable failing. I was thrown in the middle of the whole thing, almost as an afterthought, but that was okay. I was there. While an electrical contractor was pulling in a new feeder cable, the client asked if I would help with their investigation of some other faulted equipment.
This plant is located on the northern shore of a ship channel, and on the other side of the channel is a marshy area, then more river, then lake, in other words, a lot of water. The prevailing wind is from the south, laden with moisture from thirty miles of marsh between the plant and the Gulf of Mexico. It's southern Louisiana, where the night time air is saturated: 100% humidity every night from May to October. The fault occured on a soft, muggy June night.
He is setting the stage -- the incident itself:
So let's fast-forward to that sweet June night. One of the operators is making his rounds. This requires that he pass through the electrical equipment room and check a few things. And he finds the air conditioner just died. The room and the equipment is still cool, but he KNOWS it's important that it STAY cool. So he throws open the double doors on the south side of the room, opening it to that muggy breeze. And he opens the north door to the room, so that the breeze can blow straight through. The muggy night air flows in and begins condensing on the electrical equipment which is cooled below the dew point.
Happy that he'd done the right thing, the operator finishes his rounds and returns to his air-conditioned control room. And in about half an hour, there's a loud blast from the electrical equipment room, and all the lights go out, except for a few ghostly indicators powered by the UPS system.
The whole story is great. Check it out.
