emonTx5: 6-Channel Energy monitoring transmitter node

£153.88 (Inc. VAT)
£128.23 (Ex. VAT)
140.00 Grams
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The emonTx5 is a 6 CT channel as standard (12 CT channel with expansion board) electricity monitoring transmitter node, capable of single phase or 3-phase monitoring.

It transmits data via an inbuilt 433MHz radio to an emonPi1/2 or emonBase base-station.

  1. It is useful for expanding an emonPi monitoring system where more CT inputs are required either in the same location or in a different part of the building.
  2. It can also be used together with an emonBase base-station, where it is useful to have the electricity monitoring at one location and an Ethernet connected base-station in another.
  3. While the emonTx5 is primarily designed to transmit data via 433MHz radio to the base-station, it can also be connected via a direct USB-C cable connection if required.

Please see Documentation: Install for a more detailed explanation of these system arrangements.

When combined with the emonVS voltage sensor, a selection of CT sensors and a base station, it provides an end-to-end electricity monitoring solution perfect for monitoring home consumption, solar generation, EV charging, heat pumps, battery storage among other applications.

emonTx5 features:

  • 6x clip-on CT current sensor inputs (suitable for a range of 333mV voltage output CT sensors)
  • Voltage input for use with emonVs precision voltage sensor (RJ45 connector)
  • Full Real/Active power measurement (with an emonVs) & continuous sampling
  • Cumulative energy persisted on reboot (6 channel firmware)
  • Single phase, 3-phase (4-wire) and N.American split phase support.
  • 3 pluggable terminal block inputs for DS18B20 temperature sensing*, pulse counting or an analogue voltage input.
  • On-board USB-C to UART converter for easier programming and serial output
  • 433 MHz RFM69CW radio transceiver
  • Wall-mount aluminium enclosure
  • Made in UK (UKCA & CE approved)

Sensor selection guide:

1. emonVs voltage sensor and power supply selection

The emonTx5 is designed for use with the emonVS precision voltage sensor and integrated power supply which provides higher accuracy voltage and active power measurement alongside a single socket or hardwired install.

A single phase emonVs with UK plug is selected by default above. Please change to suit your application.

  • The N.American split phase option uses the 3-phase emonVs with phase 1 & 2 used for the split phases.
  • Please enquire for 3-phase 3-wire systems.
  • Shared: If you already have an emonVs in the same location it is possible to share the emonVs between multiple units with an emonVs RJ45 duplicator.
  • Current only: The emonTx5 can be used without an emonVs in current only mode. This is only supported by the 6 channel firmware.

For separate product entries, please see: 1-phase emonVs (UK Plug, EU Plug, No Plug) and 3-phase/split phase emonVs.

2. Optional: 6 channel expansion board

Expand the number of CT current channels from 6 to 12 with an expansion board.
We will fit this expansion board for you if selected above.
Separate product entry: EmonTx5 6 CT Expansion board

3. CT current sensor selection

To obtain the highest accuracy we recommend choosing CT current sensors that match the current rating of the circuit being measured. 

E.g for 16A or 20A circuits choose the 20A CT sensor, for 32A or 40A circuits choose the 50A CT sensor and so on. No damage will be done if the current in the circuit exceeds the CT rating, the output will just be 'clipped' resulting in inaccuracy.

The physical size of the CT sensors is also proportional to the current rating which makes the smaller sensors very suitable for installation inside fuseboxes / consumer units.  See individual CT current sensor product pages for more information:

Note: The emonTx5 & emonPi2 both require voltage output CT sensors, the old current output YHDC (blue) 100 A CT sensor is NOT compatible.

4. Temperature sensing*

Temperature sensing is only available when using the single phase 6 channel emonTx5_CM_6CT_temperature firmware based on the emonLibCM library. There is a slight impact on electricity monitoring accuracy when using temperature sensing, please see related forum post for the emonTx4 here. Suitable temperature sensors can be selected here: DS18B20 temperature sensors.

5. Pulse counting.

Base station options:

The emonTx5 requires a base station to complete a working system.
The base station can be an emonPi or an emonBase, available here:

The emonTx5 is also compatible with the original emonPi.