Hello.
I have a smart plug plugged in a power string, that every X months stops working properly, and when you turn it off, despite it responding, and you can even hear a “click” inside the current still flows to all the equipment plugged into it.
At first, I thought this was some problem with the previous smart plug, a cheap Tuya device, so I decided to change it and use a Belkin Wemo plug. To my surprise, after some months of proper operation the same issue started happening again, and I’m clueless about what may be happening. Two different devices, from two different manufacturers that face the same exact problem:
Every X months they still respond, they do the appropriate clicky sound when I turn them off, but the gear connected to them still gets power. After that I have to reboot them and they start working properly again.
The schematic of how they are plugged is:
wall → normal power strip → smart plug → another normal strip where everything else connects
Tom is probably right - this sounds like contact welding caused by capacative loads. Many power supplies have large capacitors in them which charge up rapidly when the power is applied. This causes a tiny area of the relays contact to vapourise or become molten and the relay then welds itself closed.
There isn’t a simple effective avoidance other than trying to find a smart switch with a better quality relay which might last longer.
Or splitting up the load. Like move the desk off the switch. The Jarvis/desky/uplift desks are calm idle - they’re only driving the control electronics but but man those motors pull when you move the desk. I’d bet that’s your culprit…
I do not have my desk on a switched outlet for this exact reason…
Thanks for all the responses.
Is contact welding something definitive? Because if it is, how is that a reboot may fix the problem?
I will move my standing desk to a separate plug to see if that fixes the problem. The thing is I liked having everything under the same strip that elevates with the desk, and I wanted all that is on the desk to get off at night, but I think it is a reasonable tradeoff.
Given the symptoms and given that you have observed this on more than one brand - it sounds like contact welding. But it could even be thermal expansion due to some type of bimetalic configuration of the relay, but without opening the relay and examining it it’s not possible to fully explain. It may be that the weld is weak and comes apart after a period, I don’t know.
It’s just a best-guess from the peanut gallery.