So I have an interesting issue and thought that HE could solve it perfectly - if I can find the correct hardware. Ultimately I think I need a very small footprint smart plug or one that is angled 90 degrees.
My single light switch in the bathroom controls both the light and the exhaust fan above the shower. The fan has a hard time with the amount of "on time" it has (and the bathroom light has to stay on for safety reasons). The way the fan gets power is a 2 plug prong in the box it's mounted in and so I thought a smart plug in the middle could provide a way to solve this - and I could use a water sensor in the shower, a motion detector, a humidity sensor, or even just a button to turn that plug on and off, thereby separating the light from the fan. The problem of course is that I need to find hardware that physically fits in the box.
(1) I don't know of a smart plug small enough to fit in that small corner but you could buy a 6 inch extension cord, plug in there, and a small smart plug in the extension and then your fan cord in the plug. I use some of Tapo Plugs that connect to Homekit. Then use the Homekit integration to bring them locally into Hubitat. That might be an option.
(2) Which is what I done to solve the exact problem you have. I installed and Aqara T2 Relay in my power supply wire going to my exhaust fan. The relay has two switches inside but I just use one side. I put the relay in the power supply wire and put a contact snesors on my door. Write the rule that when the door closes it turns on that side of the relay then of course turning on the fan. Open the door fan turns off. I also installed a humidity sensor in the bathroom and one in the other end of the house and wrote a rule to turn on the fan if the bathroom humidity is a set amount higher than the other end of the house. This allows it to work if my son takes a shower when no one is home and doesn't close the door lol or if the fan hasn't taken the humidity down enough when someone opens the door. The fan turns off then turns back on until the humidity drops.
I installed and old work box in my ceiling. Cut the house wire going from my light to my fan. Then I put the wire in the old work box and then put the relay in that box in the house wire. Then covered the old work box with a blank white cover. This allows me to easily get into the relay if needed. My fan does not have the plug like yours so I had to do differently.
However, with your setup you could splice into the power wires coming from the plug and install the relay there and achieve the same thing.
I do need to mention I have my Aqara T2 joined to an Aqara hub and brought into Hubitat via matter through the hub. I don't know if there are any community drivers out there that works. I am sure there probably is. Also, there are other relays on the market that can achieve the same thing that has drivers with Hubitat.
Yeah, looks like I need to find some sort of Zigbee relay that doesn't need a neutral and is battery powered (I need to accommodate for the light switch being turned off as well)
Or I need to install 2 relay's, one for the light as well and replace the light switch too.
I don't know of any that is battery powered but they may exist. I kept my switch the standard toggle switch and placed a cover over it so it can't be turned off. Just s clear cover from Lowes. I use smart bulbs in the light triggered by PIR and mmWave sensors then the relay for the fan. This keeps everything powered and then working independently.
Sonoff makes a no neutral relay and I think Gledopto may also. I have a Sonoff but don't have it installed. There are some threads on here about them causing Zigbee mesh instability but that might be resolved. I am not sure.
If you need to keep the light seperate some alternate method like that may work.
I appreciate you talking this through with me. You've helped me digest the issue better and I've come up with another way as a result. I'll likely install a surface mounted light connected to a regular outlet. Either the light itself or the outlet will be Zigbee enabled. Then I'll replace the single light switch with a Zigbee light switch as well. HE will then manage the setup so that if the regular light is on, the outlet goes off and vis versa (deals with ensuring a light is always on) and that the bathroom is lit regardless of if the fan is running or not. And then I can try to automate detecting the shower running and flipping the light.
I guess a cheaper / easier way would be a smart plug and standing lamp, but I need something a little less "unpluggable"
Now I just need to find a nice light that I can mount over the sink or so that will use a regular 110 outlet for power (I know, they technically all do, just have to make the plug myself).
possibly - use the other end? What I mean is that tile makes it hard to rig something - what about the light switch? can you split the feed and put 2 switches - 1 smart?
Shockingly I do. I was quite surprised, seeing as the rest of the bathroom appears to be from the 60s (no neutral wire, single wire for both fan and light (fan likely added later), etc)
No problem. That is the beauty of this type stuff. There are so many ways to achieve the end goal. No one solution is the correct solution for everyone but bouncing ideas around can help figure the right one out. Glad you have a starting point that you want to work from.
It looks like that fan is within a mounting box/duct, and it can possibly be separated from the box after unplugging it, giving you access to that outlet from behind the fan, which may open up other possibilities.
That little plug is more of a convenience allowing the fan to be removed. The real story is what is going on in the junction box above that fan where you will find the neutral wire you need for a dry contact relay. I have used a Zen51 for just such a thing but that is z-wave. A google search showed a lot of small Zigbee dry contact relays which I think would do the job for you.
I know you said the light is always on then so is the sonoff. Switching off the light also switches off the sonoff (and the fan) is there a delay in power being restored to the sonoff and being able to command it? If there is and you know how long you can incorporate it into any rule you make for it.
That's hard for me to know. If I turn off the light, the fan goes off right away. If I turn it back on 10 seconds later, the fan turns back on automatically. The green light on the relay never shuts down. If I wait a few* hours and then turn it back on, the green light on the relay is off, the fan does not turn on until I tell the relay to turn on, and my testing is that it connects right away.
I suspect the relay has some sort of capacitor in it for the zigbee radio and that it does not "shut down" right away.
Note that I spliced it in on the hot wire (tested beforehand).
