The ThirdReality Smart Plug E3 is a new EU Zigbee 3.0 smart plug with energy metering. It is an official successor to the previous gen Smart Plug E2 with about the same price tag. ThirdReality lists an upgraded Zigbee chip, factory calibration of ±1% for the meter and power change alerts as the main changes.
I paired the E3 with Zigbee2MQTT and ZHA in Home Assistant and tested every feature and exposed entity. This review covers what changed from the E2, how the E3 integrates with Home Assistant and how accurate its readings are in practice.
You can purchase the Smart Plug E3 from Amazon DE, Amazon NL, Amazon FR, Amazon IT, Amazon ES, or ThirdReality webstore.
For other ThirdReality reviews I did, check out the ThirdReality Smart Motion Sensor R1, Soil Moisture Sensor, Smart Zigbee Watering Kit, and Matter Night Light.
ThirdReality Smart Plug E3 vs E2
The E3 and E2 share the same electrical rating and most of the same core features. Here’s how both compare on paper:
 Smart Plug E2 |  Smart Plug E3 | |
|---|---|---|
| Model | 3RSPE01044BZ | 3RSPE02065Z |
| Rating | 16 A, 3680 W | 16 A, 3680 W |
| Dimensions | 50 × 50 × 83 mm | 55 × 55 × 79 mm |
| Weight | 78 g | 80 g |
| Power on behavior | Off, on, previous | Off, on, toggle, previous |
| Metering-only mode | No | Yes |
| Energy meter alerts | No | Yes, 1 to 3200 W |
| Energy meter accuracy | N/A | ±1% factory calibrated |
| Zigbee router | Yes | Yes |
| OTA | Yes | Yes |
| Relay on while OTA | No | Yes |
| Zigbee2MQTT | Yes | Yes |
| ZHA | Yes | Yes |
| Price | €13.99 | €14.99 |
The E3 adds a toggle option to the power on behavior and a metering-only mode that locks the relay ON. You can also keep the relay ON while updating the plug via OTA, something the E2 did not support. The power rise and drop notifications are also a new feature, which alert you under different thresholds. I cover how these work in the entities section below.
Design and Hardware
The ThirdReality Smart Plug E3 ships in a small company-branded box. Inside, you get the plug and a user manual. Nothing else is included, but a smart plug does not really need anything extra.
On paper, the E3 is a compact plug, measuring 55 × 55 × 79 mm and weighing 80 g. Its rounded body with sharp edges makes it look and feel bulkier than the numbers suggest. However, it does not block the neighboring socket on a standard double outlet. The build quality is quite solid, and the Type F pins are properly secured in the housing.
A single button on the housing toggles the relay and handles pairing. This button also doubles down as a status LED indicator. It’s interesting that the brightness of this LED is adjustable from Home Assistant, so it can be dimmed or turned off completely. The socket includes child safety shutters, which cover the holes and only open when a plug is inserted.
The plug is rated for 16 A resistive loads, which equals 3680 W at 230 V. ThirdReality also lists zero crossing detection, which switches the relay near the zero point of the AC wave. This reduces contact sparking and should extend relay life when the plug is used with inductive loads.
Home Assistant Integration
The E3 works in Home Assistant through Zigbee2MQTT and ZHA. Zigbee2MQTT added support in version 2.3.0 and expanded it in later releases. ZHA supports the plug through a ThirdReality quirk in the zha-device-handlers project. I highly appreciate the fact that ThirdReality contributes to both projects directly and made their own converters and quirks.
ZHA Integration (CC2652 Coordinator)
ZHA supports the Smart Plug E3 out of the box. It applies a custom quirk automatically, exposing all features in Home Assistant. All entities are present, including metering-only mode, thresholds for alerts and the toggle option for power on behavior.
The Smart Plug E3 also supports OTA updates in Home Assistant through ZHA. ZHA reports the firmware as 0x0000002f, which is version 47 in decimal, and marks it as up to date for my sample. ThirdReality lists the same 1.00.47 version for the US Smart Plug Gen3, so both plugs likely share the firmware. As is, everything works smoothly.
Zigbee2MQTT (EFR32MG24 Coordinator)
Zigbee2MQTT identifies the plug as the ThirdReality 3RSPE02065Z. The plug supports OTA updates and ThirdReality states that updates do not interrupt the relay, so the connected load stays powered during the process. My unit runs firmware 1.00.47, and Zigbee2MQTT found no newer version, so I was unable to test this feature.
Exposed Entities and Configuration
Zigbee2MQTT exposes 15 entities for the E3. Six of them are metering sensors and the rest are controls and settings. The metering-only mode and the power thresholds are available in both ZHA and Zigbee2MQTT.
- Switch turns the relay on and off.
- Power on behavior sets the relay state after a power loss. The options are off, on, toggle and previous.
- Power, voltage, current, energy, AC frequency and power factor are the energy metering sensors.
- Reset total energy clears the energy counter at firmware level.
- LED brightness sets the indicator status LED from 0 to 100%.
- Metering-only mode forces the relay to stay ON.
- Countdown to turn off and countdown to turn on set an on device timer from 0 to 65535 seconds.
- Power rise threshold and power drop threshold set the alert levels from 1 to 3200 W. Both default to 3200 W, so the alerts stay effectively off until I lower them.
The new metering-only mode is very useful for fridges, freezers, servers and network equipment. These devices should never lose power because of an accidental toggle or a bad automation. With the mode enabled, the E3 works as a pure energy meter.
The power rise and drop thresholds are another new feature of the E3. Each threshold sets a power change in watts that makes the plug report immediately. Rise and drop work independently, so I can set one without the other. ThirdReality designed them for automations, such as one plug crossing a power limit and switching another device.
This is useful for appliance state detection. For instance, a washing machine drops from hundreds of watts to almost nothing when a cycle ends. A fast report on that drop lets an automation send a notification without waiting for the next scheduled report.
Zigbee2MQTT also exposes calibration and precision options for power, voltage, current, energy and frequency. Calibration applies a percentage offset to power, voltage, current and energy, and an absolute offset to frequency. These options are useful if your specific unit reads consistently high or low.
Metering-Only Mode and Inductive Loads
To me, metering-only mode is the most practical new feature on the E3, and it deserves more than a line in the exposes list. This mode locks the relay, prevents accidental switching and makes the E3 operate as an inline energy meter only. It helps to understand what that actually means and protects against.
If you don’t already know, fridges, freezers and other appliances with compressors are inductive loads. When a compressor starts, it draws a short current spike several times higher than its running current. Many users assume this spike is what damages smart plug relays. In practice, the risk comes from the relay switching under load, not from the initial spike itself.
Relay contacts only arc at the moment they open or close. Opening is the worst case with inductive loads, because the motor resists the sudden drop in current and creates a voltage spike across the contacts. While the relay stays closed, nothing arcs. The startup surge simply flows through the contacts and lasts a fraction of a second.
The fridge starts and stops its compressor with its own controls, so the plug relay stays closed during normal operation. The danger comes from external switching events like an accidental button press, a faulty automation or a misclick on the dashboard. Each of these opens the contacts under an inductive load. Rapid off and on cycling can also force the compressor to restart against high pressure, which is hard on the appliance itself.
Metering-only mode in the E3 removes these switching events completely. The relay stays locked on and the E3 works as a pure energy meter. The 16 A rating applies to resistive loads, but a fridge running at 100 to 200 W stays far below any practical limit.
Energy Metering Accuracy
ThirdReality claims every E3 is factory calibrated to ±1% accuracy. To get an idea if this number is accurate, I used the same method as with the Sonoff S60ZB and ran both plugs on my kitchen dishwasher. I tested two programs with known consumption. The Plates & Cutlery cycle consistently uses between 1.55 and 1.65 kWh, which I have verified many times with different devices, and the dishwasher manual lists it at 1.60 kWh. The Pans & Pots cycle is rated at 1.90 kWh.
On the first Plates & Cutlery run, the E3 reported 1.61 kWh, while the Sonoff S60ZB reported 1.67 kWh. The second run gave 1.63 kWh on the E3 and 1.75 kWh on the Sonoff. Both E3 readings fall inside the expected range and sit close to the rated 1.60 kWh. Both Sonoff readings land above it.
The Pans & Pots cycle, which uses more power, showed the same pattern. The E3 reported 1.96 kWh and the Sonoff 2.01 kWh, against a rated 1.90 kWh. Both plugs read higher than the manual here, but the E3 again stayed closer.
Across all three runs, the E3 reported about 3-4% less energy than the Sonoff S60ZB, and its results were closer to the rated values every time. It was also more consistent. Its two Plates & Cutlery readings differ by only 0.02 kWh, while the Sonoff’s differ by 0.08 kWh on the same cycle.
To be clear, I do not consider a dishwasher a reliable lab reference, since water temperature and load size affect its actual consumption. This test cannot confirm the exact ±1% claim. What it does show is that the E3 tracks real appliance usage closely and consistently.
Verdict
The ThirdReality Smart Plug E3 is a small but meaningful upgrade over the E2. The power rise and drop thresholds, metering-only mode and uninterrupted power during OTA updates all solve practical problems in Home Assistant. Support in Zigbee2MQTT and ZHA comes directly from Thirdreality, which is very rare and highly appreciated.
If you are looking for a well-made, accurate and reliable Zigbee smart plug, I can comfortably recommend the ThirdReality Smart Plug E3. It does exactly what it promises, with no compromises on the core features. Another alternative worth considering is the Sonoff S60ZB, as both plugs offer excellent value for their price.
Also on Amazon FR, Amazon IT, Amazon ES, ThirdReality.
For E2 owners, the upgrade only makes sense if the new alerts or metering-only mode cover a specific need. The E2 still handles switching and energy metering well.
FAQ
Does the ThirdRealitySmart Plug E3 need a hub?
Yes. The E3 is a Zigbee device and needs a Zigbee coordinator or hub. It works with Zigbee2MQTT, ZHA, SmartThings, Hubitat, Homey and Echo devices with a built in Zigbee hub.
Does the Smart Plug E3 work as a Zigbee router?
Yes. The E3 is mains powered and works as a Zigbee router. It extends the mesh for nearby battery powered devices.
What is metering-only mode?
Metering-only mode locks the relay in the on position. The plug keeps reporting energy data but cannot be switched off. It protects devices like fridges and servers from accidental shutdowns.
Why does the E3 show power usage with nothing plugged in?
The plug reports its own consumption. ThirdReality states it stays under 1 W.
Should I replace my Smart Plug E2 with the E3?
Only if you need power change alerts, metering-only mode or better meter accuracy. Both plugs share the same rating and core features.
