Found out how many elevator cables are actually in a single hoistway and it blew my mind
I was reading through an old Schumacher maintenance manual last week that an old timer gave me. It says for a typical 20-story building with 3500 lb capacity, you need 6 separate cables running from top to bottom. Each one is about 3/8 inch thick but can hold over 10,000 pounds alone. That stuck with me because I always figured it was just two or three cables doing all the work. Has anyone else looked into the actual specs and been surprised by what you found?
Six cables for a 3500 pound car? That seems like overkill until you think about how much a full car of people actually weighs. I remember reading somewhere that a single 3/8 inch cable can handle about three times the weight of a fully loaded car by itself. The other five are basically insurance in case one snaps, which makes sense when you're launching people up and down a shaft at 500 feet per minute.
Jump right in on that. The redundancy is the whole point. You don't want a single point of failure when you're talking about dropping people down a shaft. Those cables get inspected daily too, they're looking for any little fray or kink. The safety factor is huge, like 10 or 12 to 1 on top of the weight you mentioned. It's the kind of overkill you can't really argue with.