I have three exterior light fixtures on a circuit controlled by two switches and am interested in installing an electronic timer in place of one of the switches.
Will a timer work with the second switch still attached? Are there any other issues I need to consider?
Andy

So you have a light controlled by a set of 3-way switches. Whether you can install a timer depends on how the switches are wired and whether you have a neutral at the switch you want to replace.

Intermatic has a 3 way timer switch that includes the placement of a jumper at the second three way switch, according to this video:
Intermatic ST01C 3-Way Timer Switch Installation - YouTube