Leviton Hardware & Accessories - Recent Questions, Troubleshooting & Support

https://www.youtube.com/watch?v=FdwvDJGrbK8

You posted under Leviton 6124
If this is not your timer, add a comment.

Also see Leviton timers at:
http://waterheatertimer.org/Leviton-timers.html

Leviton 6124 manual
http://waterheatertimer.org/images/6124-manual.pdf

The timer lets you adjust the preset astronomic time for your area.
This is because actual local times vary.
If the preset time for dusk is 8:00pm and you add 12 minutes, then the timer will turn off-or-on at 8:12.
And then you can change the preset time for dawn by adding or subtracting.

If this is not what exactly you are asking, then set your timer and see what happens, and then add a comment with your findings.
Open following link to download on-line manual
http://waterheatertimer.org/Leviton-timers.html

Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.

The Leviton LTB30 20 amp timer has a known design flaw. It has a 1 microfarad electrolytic capacitor installed against a screaming hot resistor. Cooks and dries out the cap even when not in use. 50% failure rate in my initial install of 4 units. Pull it apart and replace the electrolytic with a ceramic cap and it will be fine. I have two of many that have already failed. Poor design of voltage regulation and poor layout of cheap components that self destruct. Design is not half baked, it is fully baked, lol. Can be fixed though, so not all bad...

Leviton timer manuals appear following link: http://waterheatertimer.org/Leviton-timers-and-manuals.html

replace it, they are not expensive. They are a disposable item.

The following link has manuals for Leviton timers: http://waterheatertimer.org/Leviton-timers.html

Dear Dean, Generally speaking, black indicated "hot", like the color of "burnt". White indicates the color of ground. ( ice or snow) One of your black wires should be "incoming" ( that means have electricity in it NOW", and the other one would go to where the item was that was timed. After you find which wire is "hot", the other black wire goes to the opposite side of the switch. You may need to reverse the black wires if it is wired backwards to the ":on" & "off" readings. The ground would be the white wire. If you have a green screw, the ground (white) could go there.