Digital in-wall timer

QuestionEdit

QUESTION: the wall has white, black and a ground wire (old house). the timer has RED, white, black and green (which is the ground). Can this be installed without using the red from the timer?

ANSWER: Hi Ben is this timer to be used in place of a wall switch? if so do the instructions say if this is a lighted timer ? What will this be controlling?

                                                          Thank you

---------- FOLLOW-UP ----------

QUESTION: it is a digital exterior light timer mounted just inside the front door. it is replacing a wall switch. I tried to join the red and white wires with the white wire from the wall, but when the timer turns on, the light starts flashing on and off. obviously that isn't correct. do you think i will need to add the red wire to the wall?

AnswerEdit

Ben, i think you are being confused by the white wire on the timer,if there is more than the one switch in the box where you are trying to install the timer, and if the switch you are trying to replace had only a white wire and a black wire on the terminals then you need to try a little experiment. With the power off put the switch back on,turn the power back on. Now turn on all the switches in the box. Next turn off 1 breaker or fuse at a time ,we want to see if all the power in that box is on 1 breaker or fuse, if that is the case let me know, if the switch is all by its self meaning i box with 1 cover let me know that, and if you have make and the model # of the timer you are trying to install send that also,then i can answer in a few Min's how to proceed!!! thank you

  If there are only the white and black, it is called a switch leg, White from wall goes to black on timer, then black from wall goes to red on timer green goes to ground,  i asked about the timer model and make because the timer will prob. just work manually the white on the timer is for 
the operation of the timer the time may not advance without a neutral wire ,THAT is colored white in the wall box, That is why i asked those other questions model # gives that info!