Photo by Ohad

Since we’ve had two major electrical fires in Washington this week, it seemed like a good opportunity to dive a bit more into the nature of these nasty fires. Turns out these fires are more common than you’d think, and they can be extremely dangerous.

It’s looking like both last night’s fire near the White House, and Thursday’s fire near the Washington Hilton began in underground vaults containing power transformers. Here’s where I get out my old physics textbooks, fire up the Google and talk about electrical fires.

Basic stuff, what is a transformer? Simply put a transformer transfers electric current from one circuit to another. You’ve seen a transformer before, it’s that gray drum on a power pole that resembles a trash can. The transformers on power poles, or in the city in underground vaults are used to transfer current from higher voltage distribution lines to lower voltage that can be used by buildings and equipment.

So we’ve got a underground box that’s job is to take high voltage power from the grid and step it down to a useful voltage for customers. Sounds simple enough, right? Well, it is all just basic physics to get the job done, but we’re dealing with high voltage and high current and as we’ve seen it can get messy.