If you’ve already looked at the no-neutral D1 single switch (QBKG21LM), the QBKG23LM is its sibling with one crucial difference: it needs a neutral wire at the switch box. That one wiring requirement changes more than you’d expect — it affects what the device reports, how it behaves on your Zigbee mesh, and whether you get power monitoring at all.
I get asked fairly often whether these two switches are interchangeable if you swap the model number in a shopping cart. They’re not. If your wall box has a neutral conductor, QBKG23LM is the better buy. If it doesn’t, don’t try to force it — the no-neutral QBKG21LM is the model to look at instead.
What the QBKG23LM actually is
The QBKG23LM is Aqara’s D1-series single-rocker wall switch module, neutral-wire version. Its Zigbee model identifier is lumi.switch.b1nacn02, which is how you’ll see it referenced in Zigbee2MQTT logs and in the device database before it’s given a friendly name.
Physically it’s a single-gang in-wall module — it replaces the switch mechanism, not just the faceplate, and it controls one load (one rocker, one relay). The “23” in the model number sits in the same family as the double-rocker QBKG24LM (neutral) and the no-neutral pair QBKG21LM / QBKG22LM. Aqara’s naming isn’t intuitive from the outside, but the pattern once you know it: even-numbered suffixes are two-gang, and the neutral-wire versions are a separate SKU from the no-neutral ones, not a firmware toggle.
Why the neutral wire changes the story
On a no-neutral switch, the module has to steal a trickle of current through the load itself to stay powered, which is why those switches are so fussy about minimum load wattage and LED bulb compatibility. With a neutral conductor at the switch box, the QBKG23LM gets continuous mains power independent of the load. That has two consequences worth caring about before you even get to pairing:
- Power monitoring becomes possible. A no-neutral switch physically cannot measure real power draw with any accuracy — it doesn’t have a stable reference. The QBKG23LM does.
- It’s expected to act as a Zigbee router. Mains-powered Zigbee devices are supposed to relay mesh traffic for battery-powered devices nearby (sensors, buttons). This matters if you’re planning coverage in a room with a weak signal from your coordinator.
That second point turned into an actual bug for a while, which I’ll get to in a minute.
Pairing to Zigbee2MQTT
Standard Zigbee2MQTT join flow, nothing device-specific required going in:
- Put your Zigbee2MQTT coordinator into pairing mode (
permit_join: true, either via the frontend ormosquitto_pubtozigbee2mqtt/bridge/request/permit_join). - On the switch itself, hold the physical rocker for roughly 5 seconds until the LED starts flashing — this puts it into pairing mode. If it was previously paired to the Aqara hub or Mi Home, factory reset it first (same hold, sometimes needs two attempts on older firmware).
- Zigbee2MQTT should detect it within a few seconds and start the interview process. Watch the log — a successful interview ends with the device model resolving to
QBKG23LMand exposing its entity list.
The interview can stall or fail silently the first time, especially if the switch was recently power-cycled or is still holding onto stale binding data from a previous controller. If it doesn’t complete within about 30 seconds, remove the device from Z2M’s pairing state, power-cycle the switch at the breaker, and retry. This is a known class of Zigbee interview flakiness on Aqara mains devices generally, not unique to this model — but it catches people out often enough that it’s worth expecting on the first try rather than assuming something’s broken.
One thing that’s specific to certain coordinator/adapter combinations: some users have reported pairing failures tied to particular USB coordinator sticks, requiring repeated interview retries before it sticks. If your first two or three attempts all fail the same way, it’s worth checking whether your specific coordinator firmware has open issues against Aqara mains devices before assuming the switch itself is faulty.
The router-vs-end-device bug (fixed, but know the history)
This is the part that doesn’t show up on the vendor page and is genuinely useful to know if you’re troubleshooting an older setup or reading an old forum thread. Some QBKG23LM units, when paired, were misclassified by Zigbee2MQTT as a battery-powered end device instead of a mains-powered router. That’s backwards for a mains-connected switch, and it broke mesh routing assumptions for anyone relying on it to extend coverage — the mesh simply didn’t route through a device it thought was battery-powered and potentially sleeping.
The fix landed in Zigbee2MQTT 1.23.0, which forces the correct device type for this model rather than trusting whatever the device reports during interview. If you’re running anything from before that release — which, at this point, would be genuinely ancient — that’s your answer for why a QBKG23LM near your bedroom didn’t seem to help border-of-range sensors the way it should have. As of current Z2M releases this is a non-issue; I’m noting it mainly because old GitHub threads and forum posts about this device still reference the misclassification, and it’s confusing if you don’t know it’s already resolved.
Entities exposed
Once paired, Zigbee2MQTT exposes a fuller entity set than the no-neutral variant, which is really the whole reason to pick this model if your wiring allows it:
state— switch on/offpower— instantaneous wattageenergy— cumulative kWh, useful for Energy Dashboardvoltage— mains voltage readingdevice_temperature— internal chip temperature, useful mostly as a health/anomaly signal rather than something you’ll act on day to day
Compare that to the QBKG21LM, which exposes state and not much else — no neutral, no power reference, no monitoring.
Setting up power monitoring in the HA Energy Dashboard
Once the power and energy entities show up in Home Assistant (auto-discovered via MQTT if you’ve got the Z2M+HA integration wired up the normal way), add the energy entity to the Energy Dashboard under Settings → Dashboards → Energy → add device. It’ll show up as an individual consumption source.
Worth knowing: raw power readings on these chipsets tend to drift a bit from ground truth — I’ve seen deviations of 5-10% against a plug-in meter on comparable Aqara mains devices. Zigbee2MQTT exposes precision and calibration options for this device (check the Exposes tab in your Z2M version for exactly which are available — the set varies by release), so you can correct for that drift instead of living with it. If your Energy Dashboard numbers look consistently high or low against a known reference, that’s what to adjust rather than just accept.
Decoupled mode and automations
Like the rest of the D1/E1 switch family, you can decouple the physical rocker from the relay — the rocker sends an action event to Zigbee2MQTT/HA instead of (or in addition to) directly switching the load. This is the move if you want the physical switch to trigger a scene or a script rather than dumbly toggling one light. Set it via the device’s operation_mode exposed setting (control_relay for normal switch behavior, decoupled to send events only) — I run mine decoupled in a couple of rooms where the “switch” logically dims a group of Hue bulbs rather than driving current directly.
I think the neutral-wire requirement is a reasonable tradeoff for what you get. A lot of buying guides frame no-neutral switches as the more “flexible” option because they fit more wall boxes, but if you have a choice, the power monitoring alone on the QBKG23LM is worth running new wire or waiting for a renovation.
FAQ
Does the Aqara QBKG23LM need a neutral wire?
Yes. It’s a hard requirement, not optional — this is the defining difference from the QBKG21LM.
Is QBKG23LM a Zigbee router or end device?
It’s a router (mains-powered devices relay mesh traffic). Older Zigbee2MQTT versions before 1.23.0 sometimes misclassified it as an end device due to a since-fixed bug — as of current releases, it’s correctly identified.
Does the Aqara D1 single switch support power monitoring in Home Assistant?
Yes, with the neutral-wire QBKG23LM specifically. It exposes power, energy, voltage, and device temperature, all of which integrate cleanly into the HA Energy Dashboard.
What’s the difference between QBKG21LM and QBKG23LM?
QBKG21LM is the no-neutral single-rocker switch — no power monitoring, more finicky about LED load compatibility. QBKG23LM requires neutral but adds full power/energy monitoring and reliable router behavior on the mesh.
Can QBKG23LM be used without the Aqara hub?
Yes. Like the rest of this family, it’s a standard Zigbee 3.0 device and pairs directly to any Zigbee2MQTT or ZHA coordinator — no Aqara hub, no Mi Home account, no cloud dependency. If you’re deciding between the two stacks, see how ZHA and Zigbee2MQTT compare for Aqara devices.
Aqara hasn’t said anything public about extending this switch line’s on-device automation logic (multi-press timing, edge cases in decoupled mode) — if that changes in a future firmware revision, it’s worth revisiting whether local automations need adjusting.