How long do ihave to turn a curb stop cap before it comes off? I've been spinning it for a long tims with othing happening

Up to 20 twists which is about 10 full rotations. From what you say you may have a striped one or you aren't really sitting on the nut. What city are you in and does the city own the caps in your town?

How long do ihave to turn a curb stop cap before it comes off?
Are you asking about a water meter cover? A water meter shut off or a sewer line cap? Back to you, Tom

Tom, around here that's what we call the city shut off valve in your front yard.

I live in Chicago and The cap is stamped with CWW (Chicago Water Works) but when I called them they said they would come out and shut the water off for a price and then wouldn't come out to turn it back on. If it is stripped what can I do? (if anything) I have spun it full circle more than ten times.

Thanks Bob!
Jcande, Bob gave you good advice, Give it another 10 turns and then try to pry the cap off. Good luck, Tom