How do I wire my digitial timer with only two wires in my wall?

Utilitec sells 2 different in-wall timers. Both wire the same.
Open following link for Utilitec wiring instructions.
http://waterheatertimer.org/Program-wire-Utilitec-0192773.html

The reason there is 2 black in the wall is because a standard line breaking switch was used. Meaning the hot side of the light was the black wire once broken light goes off. You would hook the black from switch to black in wall and white from switch to other black in wall green is ground and red put wire nut on. Red is for a 2 switch system. Where one of two switches in same room controls same light. Its not needed. Take caution when doing this trun light on goto breaker box and flip breakers till you find the right one that powers that light. once lights off then do your thing replacing.

Open following link for written directions for wiring GE in-wall timers:
http://waterheatertimer.org/GE-timers-and-manuals.html#15071

I've tested these timers.
Here's what to do:
1) Connect green to bare copper
2) Switch has 2 wires. For now, connect these two wires to timer-black and timer-red. Choose either one.
3) In back of wall box are white neutral wires twisted together and covered with wire nut. Timer-white wire connects to these white neutral wires. This action gives power to time clock.
4) If wall box does not have white neutrals described above, then connect timer-white to bare ground wire. Bare ground connects to neutral busbar in breaker box.
5) Turn on power and click manual override button or switch. If lights turn on, timer is wired correctly. If lights do not turn on, then reverse timer-red and timer-black wires.

http://www.manualsdir.com/manuals/400481/ge-in-wall-15086-ge-smart-digital-timer.html

Manual at Hardware Innovations Click manual link to right of product photo

Sylvania SA170 manual shows that timer can automatically turn on lights at sunset time, just enter your phone area code: Timer has to wired first and power on. Manual has long list of instructions starting on page 2.

How to wire timer:
SA170 replaces on-off wall switch that has 2 wires + ground
Timer has 3 wires + no ground wire
Wires that come off switch connect to Timer Blue & Black wires
Timer white wire connects with other white wires in box - if you do not have other white wires, connect to bare ground
If timer doesn't work, switch Blue and Black wires

1) Wires in box:
Black looped to to next switch is Black hot wire
Other Black goes to fixture

2) Connect timer wires
Black timer wire goes to Black hot
Red (or Blue) timer wire goes to fixture
White wire connects to white neutral wires (usually connected together with wire nut and pushed to back of box)
Green goes to bare ground wire

Open following page for correct wiring of GE in-wall timers, and for list of timers used for 3-way.
Same wiring steps are used for almost all in-wall timers <> except those used for 3-way.
http://waterheatertimer.org/GE-timers-and-manuals.html#15071

If you are wiring Aube timer for 3-way, add a comment with brand and model number.
http://waterheatertimer.org/Aube-timers.html

For other timers, add a comment with in-focus photo of your timer for correct identification and possible assistance.
http://www.fixya.com/support/r6568559-post_photograph_fixya_questions_answers

Add a comment for more free help

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.

HI .. if the switch has only a black and white wire attached, and there are no other wires in the wall box, then you cannot use this timer switch. You need to return it and get a timer that does not use a neutral connection. The wires you have are a switch leg from the light and there is a white wire but it is not a neutral.
If there are other wires in that wall box , tell me and we can chat more about how to remedy this .

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The wires on your new switch are intended for black = power .. white = neutral . and red = lights .. with two black wires on the old switch I am assuming that there is a bundle of white wires in that wall box, the white timer needs to join that bundle ... then you need to determine which black wire is the power from the electrical panel ( voltage tester) and connect to the black timer wire .. the red timer wire connects to the other black wire in the wall..

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