Why is there a 15W / 20W minimum load required for your light switches?
Our recommendation is to have at least 15 Watts of load connected to your VER. 2.0 Z-Wave dimmers even though chances are the switch will work just fine with a single LED bulb as well. It's quite random how Z-Wave switches react to low voltage loads and it depends on compatibility with particular bulbs. While most likely, a newer type of a single LED bulb will work just fine, some of the older models or other types of non-resistive loads like CFL bulbs may damage the TRIAC element in the switch over time.
The limitation affects most Z-Wave switches on the market, it's just not usually mentioned in the documentation. This minimum load recommendation is based on our experience in performing warranty service for Z-Wave switches and plugs from different manufacturers as a retailer. Most of claims for these devices involve very low loads.
Planning to use a dimmer with a single LED bulb? We recommend going with our S2 Dimmer ZEN27 for the best LED bulb compatibility and no minimum load required!
If you're still not sure if you should be worried about this, feel free to reach out to us!