After brief power outage all of my Insteon switches and some plug-ins started working erratically. Lights flickering or not responding when on/off tapped. LEDs on switches and plugs flickering for several seconds after on/off. Performing an "air-gap" or removing power briefly restored everything to normal operation.

Can someone with a better understanding of the underlying technology please help me understand what could have caused this and more importantly, why removing power (air gap) fixed it?

Thanks

One possibility is the modules electronics got confused by the short power cycle and acting strange. An air gap or power removal then powering back up. Started the internal reset circuit to completely restart the module from scratch.

So that would clear out memory, links, etc. Does the eisy then automatically reload everything instantaneously?

In iox, you right click on the device and pick restore device

To be clear, all I did was air-gap the devices and they worked fine. I did not have to restore the devices. That is what I want to better understand. I would have thought a restore was required, but it was not.

Looks like the power failure was somehow messy in terms of either Insteon messages, or oddly resetting the microprocessors in the devices. The fact that many devices were affected is quite unusual. Maybe simply turning off the breakers to reinitialize them would have worked just as well.

Yes, on a few of the new wall plugs, there is no air-gap option. So turning the breaker off/on fixed those devices. I agree it is unusual. I have been using insteon (and x10) for over 20 years and never had this happen before. It did not appear to be a spike on the line, since my surge protector in the panel was not affected. I was hoping to better understand what happened and why disconnecting power alone would fix it.

You can factory reset the outlet which will clear its memory without having to turn off the breaker.

1. Press and hold top button for 3 seconds. It will beep, and LED will start blinking green. 

2. While the LED is blinking green, press and hold top button again for 3 seconds. It will beep and its LED will start blinking red. 

3. Quickly double tap top button and wait for the beep, then immediately press and hold top button. It will emit a long beep. Keep the top button held down until the beeping stops, then release. 

4. Outlet will double beep and both top and bottom LEDs will turn on green to indicate factory reset is completed. 

Though a factory reset isn't the same as a simple power cycle, like he did with the air gap, but not then holding the link button in until it beeps. A factory reset will require restoring the device, to restore the links.

It's interesting that a simple power cycle resolved the issue, and is certainly a good first thing to try in cases like this.