A Review of the Intermatic DT620 and HB800 Astronomical Timers

By Bill Smith, COLD, CLVLT, President WEStar Illumination, LLC

Astronomical timers are the btimersest thing since sliced bread. They help both to conserve energy and make lighting systems easier to own. I recently recorded a “How To” video for two such timers by Intermatic: the DT620CL and HB800RCH, both of which I use in my lighting business. Click here to watch.

They both have identical functionality, but differ in that the DT620 is listed for indoor use only and fits inside most transformer compartments, while the HB800 is listed as being rain tight, can be exposed to the elements and is too large to fit into a transformer compartment. You plug the transformer itself into the HB800. I mainly use the HB800 for holiday lighting and when using a Unique transformer (a number of timers don’t fit inside a Unique transformer compartment).

Both timers function exactly alike and are relatively easy to operate. They consist of:

  • Display panel
  • Four function buttons
  • Adjustment knob
  • Reset button
  • System status indicator light
  • Two outlets
  • Battery backup

What I Like
There are a lot of features to like about both the DT620 and HB800. What I mainly like is that:

  1. They offer a lot of flexibility in programming the on/off cycles for your lighting system.
  2. The programming can easily be overridden temporarily by the on/off button.
  3. The system status indicator light is helpful in determining if the lights should be on.
  4. There is a lot of programming flexibility for programming the clock for your specific location. If you in a non-standard Daylight Savings Time area you can adjust the timer to reflect time changes accurately.
  5. The batteries allow you are to program the timer while it is unplugged.
  6. The HB800 can be mounted outside and therefore can be used with any system

What I Don’t Like
Although I regularly use the Intermatic timers in my business, there are a few things that I am not crazy about:

  1. Programming both the clock and on/off events can seem somewhat complex. It seems simple once you get familiar with the instructions, but the learning curve is longer than the other timers I have used.
  2. The small text in the upper left hand corner of the display is very hard to read while in the field. There is no backlight in the display and the glare on the screen of the 620 makes it almost impossible to read inside the transformer compartment without my glasses and a flashlight.
  3. No offset programming (programming on/off times relative to dusk or dawn). The only way you can program the timer to come on at a relative time is to trick it by setting the clock to the incorrect time (by adding the offset duration to the actual time).

Overall Opinion
I like both the DT620 and the HB800 and will continue to use them. I have not experienced any problems with them in the field that wasn’t my own fault (make sure you have fresh backup batteries when you install the timers!). I used to dread having to program them because the process is more complicated that the other timers I use. However, now that I know the process cold (and you can too by watching my video!) it all seems very logical and easy—although I still have to break out my cheaters to read the display.

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