sneha_dev
@snehachatterjee · Joined October 2025
Backend developer · energy
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That cleared up my confusion, thanks Emily. Ordered a 12 V DC UPS module with a relay output and wired it to a spare input. Next mains drop was Tuesday, 11 minutes: we got one “mains failed” alarm, no offline alarms, and no gaps in the meter charts. We’ll keep the LTE buffering question for when we replace the gateway.
That makes the build much simpler. Revised design: Mean Well DIN-rail PSU fitted by the client’s electrician, my box is 5V only, the MQ-4 is gone, and the certified detector they already had (turns out there was one, nobody had wired its relay to anything) feeds an input. Telemetry is gas_alarm and lockout as booleans plus temp_c, with a Critical alarm rule on gas_alarm == true. Much less for me to worry about.
No fuse, no. And yes the mains traces are maybe 3 mm from the 5V side.
If you want lux later, a BH1750 on I2C is cheap and the same Grove wiring works.
Switched to running totals every 5 min and “increase” with 1h buckets. Unplugged it twice on purpose and the chart didn’t flinch. Jason was right as well, column 4 counted triple until I added a 150 ms debounce. Empty-column alert is next weekend’s job.
It starts at zero again. I hadn’t thought about that. No MDB on this one, I checked, it’s older than me.
Re-included the locks with S2 Access Control and the plugs with S2 Authenticated, changed plug reporting to 60 s or 5 %. The door sensors are S0-only, so I left them non-secure. Mesh traffic dropped a lot and the locks finally take commands. Also renamed the children to plug-desk-03 style and batched all plugs into one gw message per minute.
Good point, I was using node-7 style names. Will switch to room names.