Will I need a long extension cord for a 3 "circuit" labyrinth in my parking lot?

Fortunately not.  99.999999% of all parking lot labyrinths are solar powered.

But as for "circuits"... in their never ending quest to classify, sort, and label labyrinths the primary definition of a labyrinth is how many hops over a line you'd have to make to reach the outside path.

Here is a diagram of a 7 "circuit" labyrinth:

And by the way, you want to hop over as many lines as possible to get to that outside path.  Don't cheat and hop into empty spaces then walk to the next line.  This is a 5 circuit labyrinth even though it's possible to only hop over 3 lines to get to the outside path:

NOT a 3 circuit labyrinth!