I’m researching lighting controls for my new house and came across the ZBMINI from SONOFF. It seems like a good solution as it checks a number of boxes. But I find the product documentation somewhat lacking in answering practical questions, so I’m hoping someone here has experience.
A) How does this device function when not connected to a Zigbee hub (like say the hub is malfunctioning or unplugged)? Does it just use the switch signal to control the relay – thus acting like a dumb switch?
B) What happens if the switch signal and the automation signal get out of sync? For example, let’s say I pull into the garage and the basement lights automatically come on with a motion sensor. But this is from an automated signal and not the switch. The switch signal is still in the off (open) position.
So if I walk upstairs and hit the switch at the top of the stairs, what does the unit do? Does it recognize the change in state to the signal line and turn the light off? Or does it recognize the switch signal is now in the on (closed) position and leave the light on? If the latter, do I have to flip the switch on and then off again to turn the light off?
C) This seem to targeting retrofit applications, so I think they’re assuming you will just use your existing NM cable for the signal wire. But I’ll be using these in new construction, so 12-guage wire seems like overkill (I’m assuming the signal line is 5V or 12V). Is it safe to use 18-guage wire (like for low-voltage lighting) for the signal line? And would using it pass US electrical codes?
In the absence of other information, I’ve been doing some first-hand testing of the ZBMINI. Here are my conclusions to some of the questions above.
B) When the Zigbee hub is not working, the ZBMINI does still function with the physical switch, just as if the digital relay was not present.
C) The ZBMINI does not seem to pay attention to whether the switch is on or off (open or closed), but functions more like a 3-way switch where the ZBMINI senses the change in the switch state and changes the state of the relay. In other words, the ZBMINI doesn’t care whether the switch is going from open to closed or closed to open, just that it’s changing state.
I’m assuming the ZBMINI actually does know the true state of the switch, but it either doesn’t pass that info on to HA or HA doesn’t show it in any way. The on-off indication in HA is based on the state of the relay.
All that to say, there doesn’t seem to be any concern with the device getting out of sync.
D) The inspector I talked with said a device like this was acceptable for US codes because it had the manual switch override. He also said that using 18-guage wire for the switch would be acceptable as long as the load and line used proper gauge wire for the circuit’s rating.
However, he also said that in order to pass inspection a device needs
to be UL rated, which the ZBMINI is not. It has a CE certification
(although I’ve read that this is self-certification), but not UL. So these cannot be used in any places that will need to have an electrical inspection -- at least not unless or until Sonoff adds UL certification.
So if anyone knows of any economical switch-controlled relays like
this that are UL rated, I would love to have a recommendation.
My zbmini is connected to a two way rocker switch. It turns on-off through Ewelink but not manually using the switches. Could a wrong wiring of the switches damage it?
I don't know much about it. But I would like to know more. Thank you so much!
Initially zbmini 2-was smart switch (was added to zbBridge) and was connected as follows:
Power and light bulb as per wiring instructions.
Connection to 2-way switches wired to common, might have been wrong but again these wires were red and may be live.
Now I have corrected the wiring but I can turn the lights on only through my wifi. Rocker switches do not work.
Could this damage zbmini?
Thanks and regards
"Could this damage zbmini?"
Possibly. I'm not sure I follow exactly what you did, but I don't think the S1 and S2 terminals were designed to take line level voltage (aka mains power). You wire your power through the L and N terminals and then just wire a 2-way switch directly into the S terminals. Using this configuration you should be able to control the relay with either a digital signal (eWeLink, HA, etc.) or manually by flipping the switch.
Also NB, most 2-way switches (at least in the US) are marked on-off, but the ZBMINI ignores that and just changes the state of the relay when the state of the switch changes.