I wanted to offer a quick report on a small DYI project I just finished in hopes that other folks in the community might find this useful.
Problem:
I wanted to be able to control the power an A/C unit that takes 240v 20a input (NEMA 6-20 type plug). The few off-the shelf solutions I found (ELK9200, Intermatic CA3750 and Aeon ZW078) would’ve all involved heavy-duty wiring, which I wanted to avoid doing. Additionally, NEMA 6 plugs/receptacles seem to be expensive and hard to find.
Solution:
I decided to take a dumb (non-connected) heavy duty timer, and modify it to be controllable with Z-wave. The components I used were Oracle Garden Supply 240v Digital Timer ($20 on eBay) and Fortrezz MIMOLite Z-Wave relay ($60 on Amazon).
I got lucky and the timer turned out to have been built in a modular way, where the timer control logic and the heavy duty relay are not soldered together, but connected via a 5 pin header. With a bit of reverse-engineering, I figured out that the bottom 2 pins control the heavy-duty normally-open relay (when the pins are unconnected the relay is open).
From there it was a simple matter of wiring up these pins to the normally-closed terminals on the MIMOLite, and – voila – I had myself a smart heavy duty power switch.