Your dishwasher isn’t smart yet? Not for long! In this article I’ll show you how to bring any old appliance up to speed with one simple trick – no rewiring, no cloud, just a small smart plug. The same principle works equally well with washing machines, dryers, or any other household appliance that runs a cycle and then gets forgotten.
What you get out of it
- Automatic notification when the cycle is done
- Saved standby power
- Increased safety at home
- Ability to switch the appliance off remotely
The idea: energy monitoring instead of cloud
Many new appliances are “smart” – but usually only through manufacturer-dependent clouds. Why buy something new when the existing machine still works perfectly? With a smart plug like the Shelly Plug S (or any other relay with energy monitoring) you can retrofit any appliance and integrate it into Home Assistant – completely local, no cloud required.
The following devices are suitable for this project:
- Shelly Plug S (affiliate link)
- Shelly Plus 1 PM (affiliate link)
- Sonoff POW R2 (affiliate link)
- Sonoff POW Elite (affiliate link)
- Smart Plug (affiliate link)
Note: Links marked with affiliate link are affiliate links. As an Amazon Associate I earn from qualifying purchases. This means I receive a small commission if you purchase through these links — at no extra cost to you. The revenue helps me run this blog and YouTube channel and keep creating content. Thank you for your support!
― Joachim
How the detection works
The idea is simple: the power consumption of the appliance is measured. If it exceeds a certain threshold for a certain period of time, the wash cycle is running. If it drops below that threshold – again for a defined period – the appliance has most likely finished. To prevent the automation from reacting to every small spike, a hysteresis is built in, meaning a delay or waiting period.
Determining typical values
Measure a complete cycle of your appliance and observe the power draw. In my case, that’s more than 5 watts for at least 5 minutes (appliance running) and less than 5 watts for at least 5 minutes (appliance done). The exact values can vary depending on the model – experiment and adjust the thresholds accordingly.
Implementation in Home Assistant
I also walk through this step by step in the video – feel free to check it out for the screencast!
- Add the device: Integrate the Shelly Plug S or another smart relay with energy monitoring into Home Assistant.
- Create sensors: Set up threshold sensors (e.g. using a template or a threshold sensor) that detect the appliance’s status.
- Automation: Create an automation that notifies you when the appliance is done – or that cuts power to the device completely after the cycle finishes.
Practical example: saving standby power
You can also see this workflow in the video as a screencast – check it out if you want to watch the implementation live!
After the wash cycle, I switch the dishwasher off completely. My appliance draws 4 watts in standby – that’s 35 kWh per year, or roughly €12 at €0.35 per kWh. You still need to subtract the smart relay’s own consumption of about 1 watt, which leaves around €9 in savings per year. That means the Shelly Plug S pays for itself in just over a year. Take a measurement on your own appliance – you might be surprised what a power drain it actually is.
Benefits & safety
- No more standby, no voltage at the appliance
- Greater safety (e.g. when away from home for longer periods)
- Control and monitoring from anywhere
Conclusion
With a simple smart plug and Home Assistant you can make any old appliance smart – no cloud, no rewiring, and no vendor lock-in. You save electricity, improve safety, and always know whether your dishwasher (or any other appliance) has finished its cycle.
→ This video generated a lot of feedback. I’ve compiled the most useful practical tips from the community in a follow-up article: Making your washing machine & dishwasher smart? 5 things you should know!