“Shortly after touching down in Tokyo, we were standing in KDD’s landing station in Ninomiya, Japan. I’ll describe it to you.
A surprising amount of space in the station is devoted to electrical gear. The station must not lose power, so there are two separate, redundant emergency generators. There is also likely to be a transformer to supply power to the cable system. We think of optical fibers as delicate strands consuming negligible power, but all of those repeaters, spaced every few dozen kilometers across an ocean, end up consuming a lot of juice: for a big transoceanic cable, one or two amperes at 7,000 or so volts, for a total of something like 10,000 watts. The equipment handling that power makes a hum you can feel in your bones, kicking the power out not along wires but solid copper bars suspended from the ceiling, with occasional sections of massive braided metal ribbon so they won’t snap in an earthquake.
The emergency generators are hooked into a battery farm that fills a room. The batteries are constantly trickle-charged and exist simply to provide power during an emergency - after the regular power goes out but before the generators kick in. Most of the equipment in the cable station is computer gear that demands a stable temperature, so there are two separate, redundant air-conditioning plants feeding into a big system of ventilation ducts. The equipment must not get dirty or get fried by sparks from the fingers of hacker tourists, so you leave your shoes by the door and slip into plastic antistatic flip-flops. The equipment must not get smashed up in earthquakes, so the building is built like a brick shithouse.
The station is no more than a few hundred meters from a beach. Sandy beaches in out-of-the-way areas are preferred. The cable comes in under the sand until it hits a beach manhole, where it continues through underground ducts until it comes up out of the floor of the cable station into a small, well-secured room. The cable is attached to something big and strong, such as a massive steel grid bolted into the wall. Early cable technicians were sometimes startled to see their cables suddenly jerk loose from their moorings inside the station - yanking the guts out of expensive pieces of equipment - and disappear in the direction of the ocean, where a passing ship had snagged them.”
