About the Outlet In Use characteristic

What is it?

This plugin exposes your Energy Socket to HomeKit as an Outlet (technical docs). An Outlet is one of the many accessory types HomeKit uses to categorise certain devices and allows you to control it from within the Home app. This Outlet accessory has several Characteristics, where On and OutletInUse are the ones this plugin uses.

I'll explain OutletInUse here.

Example real world use case

To explain this I'll use my own real world use case. Like most people, I have a washing machine at home to do the laundry. This machine sits on the top floor in my house and is connected to an Energy Socket. By observing the power usage of my washing machine, I know that when it is using more than 10 watts of power, the washing machine is busy doing the laundry. If it is using anything below 10 watts it's in standby mode. If it's using 0 watts it's off.

With the OutletInUse characteristic we can notify HomeKit if usage on the Energy Socket changes. For example, if the washing machine is using more than 10 watts of power, for at least one minute, set OutletInUse to Yes. If it falls below 10 watts we set OutletInUse to No. Now our Apple Home knows about this, and we could trigger automations based on the OutletInUse characteristic of this Energy Socket. We could, for example, run a Scene that plays a sound on my Sonos speaker down in the living room notifying about the laundry being finished on the top floor.

You can set the behaviour of OutletInUse for each Energy Socket in the plugin's config options within Homebridge.

Use the "Verbose loggin" option in the plugin settings to determine what your threshold should be. The verbose logging option will log the power consumption every second and shares information for you to determine the right treshold for your machine.

Use in automations

Although the Apple Home app exposes the OutletInUse characteristic when you view the accessory details, we cannot do anything with it in the Home app as of now. This is a limitation of the Apple Home app, not of this plugin. Home Automations with the OutletInUse characteristic currently only work in third-party Home apps, like Eve for HomeKit or Controller for HomeKit.

But you cán create a Personal Automation from within the Shortcuts app to trigger something based on the OutletInUse characteristic, as that value is available there when you select the Energy Socket accessory from your Home.