The timer is connected to lights, manual switch does not turn them on or off, but it snaps crisp and clean, trippers hit the switch and moves it into the on or off position, but does nothing. But lights will turn on and off by itself. When light is on, with manual switch in off position, turning the breaker off and then on, will close the light, but then light will just turn on by itself after 30min to 1 hour. This is old installation that stopped working.
The contacts inside the time clock have most likely warn out. If it is coming on randomly it is not making good contact and will create arcing, which is dangerous. Call an electrician, they may be able to replace just the internals.
SOURCE: pool timer stopped working
look on the dial to see which way it turns, it has time markings on it and turns the way it needs to in order to keep time, if u pull it out to set it, then u push it back in for it to work and vice versa
SOURCE: Timer works fine. In on position, pool pump does not turn on
Most likely problems: The switch contacts in the timer are burned or, there is a loose connection or, the lever linkage is loose.
Need to turn off breaker and inspect for these potential failures.
More info, let me know...
Charlie
SOURCE: T104R timer clock has stopped working. I have to
If you can also turn the pump on and off manually by turning the dial, then the timer motor is bad.
SOURCE: I have the same above T104 Mechanical Time Switch.
If i understand correctly, you have T104 240V timer that has worked fine in the past.
If this is true, then breaker is correct size.
If this is new installation, then check wiring at timer, and then add up total watts of Load and divide by 240 to check if breaker is sized correctly
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html
http://waterheatertimer.org/B220C.html
If timer worked fine in the past: It seems you have a short somewhere, which is puzzling why it trips when when timer turns OFF.
And the short could be inside a bad breaker -or- inside the timer -or- possibly a wire.
Move wires from 240Breaker to another same-size 240V breaker and see if problem persists.
After moving wires to another breaker, use manual override to check if suspect is the breaker or possibly a short in the timer.
Absolutely stand on dry surface or dry boards when working on this timer, to be on safe side.
Manual override should switch Load on-off, and override should snap clean and crisp each time.
If manual override lever is not crisp, then that signals timer has gone bad.
Also snap mechanism out of box using thumb-spring at top of box, and look for signs of burning and high heat, especially at contacts.
If you buy new timer, the inside mechanism can be swapped out without changing the box.
Add a comment and let me know what you find out, and I will respond if needed.
This is interesting puzzle.
SOURCE: I have a new Intermatic
I suspect the wiring to Load is reversed with wiring from circuit breaker.
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html
Open following link for troubleshoot checklist:
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html
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Trippers for T-104 series 
Trippers for 15 minute time-interval timers
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