The Lord of the Rings: The Fellowship of the Ring is about 178 mins. The Lord of the Rings: The Two Towers is about 179 mins.The Lord of the Rings: The Return of the King is about 201 mins.
If you are talking about an electrical ring main it can be as long as you want it as long as it returns back to the circuit breaker with the other end of the cable, which if you didn't return the 2nd...