When my primary residence was built in 1998, the builder installed a Lutron HomeWorks whole-house lighting system. Basically, it’s a set of three panels (one on each floor) that can control all the lighting loads in the house. It also allows any keypad in the house to control any light in the house, providing a lot of flexibility with programming “scenes.” Back then, the system was “top of the line” technology. But as with all things electronic, newer revisions of both hardware and software have pre-empted it.

Most of the newer features, however, I don’t really need. But there is one feature that the newer HomeWorks systems have that my original system doesn’t: an astronomical clock.

An astronomical clock is a fancy word for the ability to control lights using the calculated times of sunrise and sunset —  which times vary depending on your geographical location. My original HomeWorks system offers multiple timer functions, which work great if you want to have your bedroom lights dim up slowly every weekday at a specific time to help you wake up, or trigger an “all off” command every night at midnight to turn off any interior lights that anyone forgot to turn off. Because sunrise and sunset times move around widely throughout the year, using a timer function for the external lights just won’t work. So to have my HomeWorks system turn on the lights at sunset, and turn them off again at sunrise, was impossible without figuring out some “outside the box” solution.

My first solution when I bought the house back in 1999 was to use a combination of three accessories to kind of achieve what I was looking for. I combined a Lutron HWV-IP5 keypad with a dual-pole single throw contactor (a Square D 8910DPA32) and a standard photocell.

Lutron HWV-IP5 Keypad

The HWV-IP5 keypad interfaces with the HomeWorks system and works as a normal keypad to trigger any lighting functions (or “scenes”) programmed in the system. But in addition to the normal keypad buttons, the HWV-IP5 has dry-contact closures, which can allow third-party equipment virtually press a button to trigger the lighting scenes. So I programmed one of the keypad’s buttons in “maintained” mode, meaning that the button would need to be “held down” to tell the system to turn on the exterior lighting scene. When the button was released, all the exterior lights would turn off. The contact closure for that keypad’s button was then wired to the dry contact side of the 8910DPA32 contactor:

Square D 8910DPA32 Contactor

The line voltage side of the contactor was then wired to the photocell, and the photocell was connected to a “hot” lead in a junction box in the garage. My intent was that the photocell would sense when it got dark, trip the contactor, which would “press and hold” the button on the HWV-IP5 keypad, which would then turn on (and keep on) the exterior lights. At sunrise, the photocell would kill the power to the contactor, which would break contact with the keypad, which would virtually “unpress” the button, and the lights would turn off.

This worked ok… for a while. The photocell would fail and need to be replaced every few years, and as landscaping matured it would cast heavier and heavier shadows on the photocell location, and sometimes on overcast days (of which Seattle has a few), the exterior lights would just stay on all day… wasting lots of electricity.

Years later, after reviewing the excellent Honyewell EconoSWITCH units that I use at our Utah and Eastern Washington houses to trigger exterior lighting that isn’t controlled by a computer, I decided I’d try to use those same astronomical clock features of that switch to control my exterior lights via the Lutron HomeWorks system. Because everything was mostly wired and scenes already programmed as it needed them to be, I merely had to remove the photocell, wire in the EconoSWITCH in its place, program my latitude and longitude, set the clock, and let it do its thing.

Honeywell EconoSWITCH RPLS740B

I’m happy to report that this works perfectly. The EconoSWITCH now triggers the contactor at sunset, which “holds down” the appropriate button on the keypad, which activates the scene (check my EconoSWITCH review to see how easy this is to program and configure for your latitude and longitude). At sunrise, the lights turn off.

So if you’re using a timer or a photocell to control your exterior lighting (whether or not it’s wired to a once-top-of-the-line-but-now-dated lighting control system), consider switching to an astronomical clock to make sure your lights are coming on and off when you want to.

I welcome your questions and comments below!