To Hump Or Not To Hump

'Cause I Dunno About Banging A 150,000 Volt Transformer...

I've been mystified by a sign on the side of a piece of electrical apparatus that's being erected on the outskirts of downtown. They're putting in a step-down transformer right next to the HOV lane exit near the Aquarium, and that 1/2 block area is just chock-full of gigantimous cables, big towers with 8 foot long ceramic insulators, weird drum-like spool thingamabobs suspended from wires, and two huge transformer-looking things covered with about 2 dozen cooling fans and assorted machinery.

Attached to the side of each of these giant transformers is a sign saying, in big block letters,

DO NOT HUMP

Uh, if you insist, señor! No way I'm getting jiggy with that monstrosity!

I thought to ask this guy about it. I asked my brother-in-law, who's an electrician, but he said his area of expertise ends at light commercial and residential power levels, and he's not hip to the really supercharged stuff.

I found my answer, though, in Google. The always useful 'Straight Dope' by Cecil Adams had the answer,

Turns out that it's not electrical at all, but rather a railroad term. These big-ass transformers are shipped on flatbed rail cars, and are sensitive to being banged around. "Humping" is a term for using natural hills in a railroad shipping yard to let gravity shift cars around instead of a switching locomotive. The downside to "humping" is that you can't decelerate a car that gets to moving too quickly, and it rams the next car in line pretty hard. This damages cargo, and sometimes overturns freight cars.

The last thing you want to be going is cracking open the innards of electrical transformers stepping down that kind of power. We'd have crispy critters for blocks around if that thing starts arcing!

So, there's the reason you shouldn't hump transformers! Well, one of them anyway.