zappi v2Installation

  1. Installation
  2. Electrical Installation
  3. Wiring
  4. eSense Input (economy tariff)
  5. Current Transformers (CTs)
  6. Wiring Diagram Overview
  7. Fitting the Cover
  8. Advanced Installation Options

1. Installation

When installing and wiring the zappi care should be taken to maintain the IP rating of the unit.

Ensure that the grommets and bungs provided are fitted, the O-ring behind the cover is seated correctly and that the incoming power & CT cables are fitted using an appropriate size and type of gland.


Step 1: Carefully remove fascia from the zappi  by pressing the 2 clips located at the bottom of the unit inwards whilst pulling the fascia towards you.


Step 2: If installing a tethered zappi, you must ensure the cable wall guard is fixed to the unit using the 4 screws supplied. If installing an untethered zappi go to the next step.


Step 3: Remove all 8 screws from the enclosure and carefully lift away.


Step 4: There are 4 possible cable entry positions, carefully decide which one you are going to use from the below image. You will need an IP65 or above rated cable gland. Carefully drill the hole into the unit to match the size of your cable gland. Attach cable gland ensuring IP rating is met.


Step 5: Using zappi template, mark the mounting holes. For fixing to brick, use the top and 2 bottom holes (left/right). Use the 2 vertical holes as well as the top hole if mounting to a stud wall or joist.


Step 6: To maintain the IP rating of the unit, you will need to add bungs (provided) to the unused holes.


Step 7: Secure the unit to the wall using the fixing kit provided. Ensure the grommets are used to maintain its IP integrity.

Note: if using the rear cable entry remember to insert the mains cable before mounting to the wall!


Step 8: Ensure O-ring is present and sits neatly into its channel.


2. Electrical Installation


WARNING! an electric shock can be fatal; electrical connection work may only be carried out by a competent person

The earth conductor must be correctly installed and reliably connected

This device must be equipped with an over-current protection device of maximum 32 Amps (B32)


The single phase zappi should be connected to a 230V/240V nominal AC supply. The supply should run from a dedicated 32A circuit breaker.

The 3 phase zappi should be connected to a 400V, 4 wire, 3 phase supply. The supply should run from a dedicated 3 pole 32A circuit breaker.

We recommend the use of curve B circuit breakers.

The zappi features an integral 30mA Type-A RCD with 6mA DC leakage detection and therefore an external RCD is not usually required (unless the wiring system used to supply zappi requires one in accordance with local wiring regulations).


The zappi unit must be earthed in accordance with local regulations.

When installed on a PME (TNC-S) electrical system it is necessary to protect the consumer from a potential electric shock that could occur if the combined Neutral and Earth (PEN) conductor on the supply becomes damaged or disconnected.

zappi includes an additional automatic disconnection device which satisfies the requirements of BS7671:2018-amd1:2020 722.411.4.1 (v) (the 18th Edition IET Wiring Regulations).

This protection device:

    a) monitors the supply to identify if there is a problem with the PEN conductor and

    b) disconnects the supply if a situation arises where the end user might suffer an electric shock

This means that the zappi can be installed without the need for an additional earth rod.

However, if the customer or local regulations require that an earth rod is installed (for instance as part of a TT earthed system) then this should be connected to the dedicated terminal on the main circuit board using a ring terminal (as shown below).

3. Wiring

Insert mains cable through the installed cable gland (if not already done so) strip back outer sheath ensuring all cables reach the terminal blocks (leaving a little excess) strip back all coloured cables approx 10mm.




If using hard wired CT clamps, now is the time to insert these too (we recommend a specialist cable gland that can accommodate multiple cables whilst still maintaining IP integrity).

Do not overtighten the electrical terminals. The recommended torque setting for the electrical terminals is 2Nm

Single Phase Wiring

For single phase installations please follow the below diagram

Earth = Green / Yellow cable

Neutral = Blue Cable

Live (L1) = Brown Cable

The recommended torque setting for the electrical terminals is 1.2Nm

For single-phase installations, without the need for hardwiring an external CT, please follow the below diagram.

For single phase installations where 1, or more external/additional CTs are required, please follow the below diagram to connect the CT’s using the extra 3 CT terminals in the same way if required.

Positive (+) = Red

Negative (-) = Black

Three Phase Wiring

For 3 phase installations please use the below diagram.

Earth = Green / Yellow Cable

Neutral = Blue Cable

Live (L1) = Brown

Live (L2) = Black

Live (L3) = Grey

The recommended torque for the electrical terminals is 1.2Nm

For 3 phase installations, without the need for hardwiring an external CT, please use the below diagram.

For 3 phase installations, with the need for 1 or more external/additional CTs, please use the below diagram.

Positive (+) = Red

Negative (-) = Black

For more details on CT installation and connection see CT Sensor Installation.

4. eSense Input (economy tariff)

zappi has an input which can be used to sense the availability of economy tariff electricity, this can be used to automatically boost the charge when in ECO or ECO+ charging modes. The eSense input can also be used to limit or stop the zappi output on an external signal.

The eSENSE input is electrically isolated and effectively draws no current so the cable size is not important. An AC voltage (between 100V and 260V) across the L and N terminals of the eSENSE input cause the economy tariff symbol (e) to be shown on the main screen. The eSENSE Earth terminal is not required to be connected if you do not want to use this feature or do not have an economy tariff.

See eSense on for details of how to configure the eSENSE input.

Connect the eSense cables using the diagram below.

Neutral = Blue cable

Live (L1) = Brown cable

There is no need to earth the eSense cable although an earth terminal is available in the zappi if the cable used has an earth wire.


5. Current Transformers (CTs)

CT Sensor Installation

Current Transformers (CTs) are used to measure current at various places of the installation. For example, the Grid connection point, the solar/wind inverter or a static battery system.

Installation of a CT to monitor the Grid connection point is required for ECO modes. Other CTs are optional and can be purchased separately. The number and location of CTs used within an installation will vary according to the devices installed and the user requirements.

CTs can be wired to any myenergi device with CT inputs (e.g. eddizappi or harvi). This allows for flexible installation as a CT can be wired to the nearest device.  Ideally the grid CTs should be wired to the master device.

Note: The harvi device can be used (wirelessly) if it is not practical to connect any CT to the eddi or zappi.

Single Phase:

A CT clamp must be placed around the live meter tail as shown below with the arrow pointing towards the consumer unit.

Note: the clamp can be placed on the neutral tail, however the direction of the arrow shown will need to be reversed


A CT clamp must be placed around each phase with the arrow pointing towards the consumer unit

(Note: A CT cannot be clipped on to the neutral in a 3 phase systems)

Once installed, the CTs need to be configured, see CT Config for details of how to configure the CTs.

If using a single-phase system, the wired CT sensor (supplied) ideally needs to be clipped around the live conductor leaving the meter tail with the arrow (located on the side of the CT) pointing towards the consumer unit. It is possible to use the Neutral conductor, however you will need to reverse the direction of the sensor (arrow towards the meter).

If using a 3-phase system, a CT sensor (supplied) needs to be clipped around each live tail.

CT Golden Rules

The positioning of the Grid CT sensor is crucial, please take note of the following when deciding where best to install the sensor:

–   The sensor can be connected to any myenergi device with a CT input e.g. the eddi, zappi (wired sensor) or harvi (wireless sensor)

 ALL the import and exported power must be ‘seen’ by the sensor. Ensure that it is installed before ANY junction box or ‘Henley Block’ (if necessary, the CT can be fitted inside the consumer unit)

–   There must be only one Grid CT per-phase for the whole installation (There can be other CTs but only one at the grid connection point, also note CTs for third-party devices do not matter)

–   The CTs can be clipped on either the Live or Neutral cable on single-phase systems. (Note: you can only use the Live tails on the 3-phase system)

–   The arrow on the bottom of the CT sensor must be pointing towards the consumer unit (in the direction of grid import) if on the Live cable, or reversed if on the Neutral cable (single phase only)

–   Ensure the CT is fully closed and clicks shut

–   Be sure to wire the CT the correct way round; black (-), red (+). Failure to do so will see the import and export readings swapped

Additional CTs

There is an option to add other CT sensors (available separately) for monitoring the generation or other appliances such as battery systems or general loads. Installing a CT for the generator (PV system or wind) will allow the main screen to show the generated power and the total power consumption of all the other appliances in the property.

CTs can also be used to limit the power drawn from the supply – see Load Balancing / Current Limiting

–   Additional CTs can be connected to any myenergi device with a CT input that is linked to the network – see Linking Devices.

–   The arrow on the bottom of the sensor must be pointing in the direction of normal power flow (e.g. away from the PV inverter) if on the Live cable, or reversed if on the Neutral cable

–   Ensure the sensor is fully closed and clicks shut

–   Be sure to wire the CT the correct way round; black (-), red (+)

Extending the CT Cable

If there is a need to extend the CT cable, twisted-pair cable such as CAT5 must be used. DO NOT use mains cable, bell wire or speaker cable. It is important to use only twisted-pair cable to maintain signal integrity. Up to four CT cables can be extended using the separate twisted pairs in a CAT5 Ethernet cable. The cable can be extended up to 100m.

When joining CT wires make sure that the ends of the wires are twisted tightly together and joined using crimps, screw terminals or solder.

Avoid using lever clamp type terminals as these do not provide a reliable connection at very low currents.

Wireless CT Sensor (Optional Accessory)

In some cases it can be difficult or impractical to install a wired sensor. For example it may be the case that the zappi unit needs to be connected to a sub-board, rather than main consumer unit and two consumer units are in different buildings.

The solution to is to install harvi – a clever device that enables the zappi and eddi products to be installed without using wired CT sensors; instead the CT sensor is connected to harvi.


The harvi does not need batteries or a power supply – the energy from the sensor is harvested and used to transmit the measured signal to the zappi or eddi. This means batteries or electrical wirings are eliminated!

Up to 3 CT sensors may be used with harvi and it also supports 3-phase systems if three sensors are connected.

Refer to the harvi installation guide for details on installing and configuring harvi for your system.

CT Golden Rules

Grid CT

–   Only ONE Grid CT per phase (check for only one ~ symbol in Linked Devices Info)

–   Positioned to ‘see’ ALL import and ALL export current (i.e. always upstream of any junction box)

–   Arrow pointing in direction of import (e.g. towards consumer unit if on Live cable)

–   Must be on the same phase as master myenergi device

All other CTs

–   Arrow should point towards the consumer unit

3-Phase harvi CTs

–   When using harvi in 3-phase mode, the CT inputs correspond to the phase number (e.g. CT1 = Phase 1)

CT can dos

–   Can be wired to ANY myenergi device in the network

   harvi can be used to make ANY CT wireless

–   Cable can be extended up to 100m (muse use twisted-pair cable e.g. one pair of CAT5). The CT cable can also be shortened

–   Can be clipped around two or more conductors feeding appliances of the same type (e.g. two Live cables from two inverters that are on the same phase)

–   Can be in close proximity to other CTs

–   Wires can be swapped around in device to reverse the direction of the readings (e.g. change import to export)

–   Can be grouped with other CTs of the same type so that the power reading is summed (e.g. east and west solar generation)

–   Can be used on the Neutral conductor in a single phase installation (direction of arrow or wires must be reversed)

–   Can be set to none in the zappi menu if you want to exclude the reading

6. Wiring Diagram Overview

7. Fitting the Cover

Step 1: Offer cover to the enclosure, ensuring all cables are neatly inside the unit.

Take particular care that the ribbon cable is not trapped between the cover and the case

Ensure O-ring (seal) is firmly placed into the channel and secure the cover to the unit using the 8 screws that were removed earlier (Torque setting = 1.2Nm).


Step 2: Add fascia to the enclosure cover of the zappi as shown.


Step 3: Ensure the 2 tabs at the bottom of the fascia click to indicate it securely fixed into place


Step 4: zappi is now ready for operation


8. Advanced Installation Options

Load Balancing / Current Limiting

CTs can be also used to limit the current drawn by myenergi devices to avoid overloading circuits; this is referred to as load balancing or load curtailment. There are four different ways to limit current and they can be used alone or combined for more complex situations. See the table below:

Function Operation Example
Device Limit Sets a maximum current that can be drawn by the device (e.g. zappi). The current will not be exceeded even during Boost or Fast charge. A zappi is wired to a 20A supply (rather than 32A). The maximum current drawn will not exceed the set limit (e.g. 20A).
Grid Limit Sets the limit that can be drawn from the grid connection (i.e. the maximum import current). The zappi and any other linked myenergi device, will limit the current they draw if there is a danger of exceeding the set Grid Limit. A property may have a grid supply limit of 65A. Several appliances are on, so the property is consuming 12kW (52A). The user wants to charge in FAST mode. Without the Grid Limit set, the total consumption would exceed the allowed import current and trip the supply or blow a fuse. However, with a Grid Limit setting of 60A, zappi would temporarily limit the charging current to 8A (about 1.8kW) and the maximum allowed import current would not be exceeded.
Group Limit
(internal CT)
Sets the combined current limit for several myenergi devices. A property has a large PV, a swimming pool and two zappis. The supply to the zappis is only rated at 40A so to be safe a Group Limit of 40A is set.
Group Limit
(external CT)
Sets the combined current limit for several myenergi devices that are sharing a supply with another large appliance. A zappi is installed in a garage which also has a washer and a dryer (2.5kW each). The garage has a supply of 32A coming from the main consumer unit in the house. If all appliances were on together and no limit had been set the total current would exceed the maximum supply current. By setting the Group Limit to 32A an overload will be avoided.

Three-Phase Systems

If the installation has a three-phase supply, you can use the 3 CT connectors either directly connected to the zappi (hard wired) or a harvi device (wireless – optional). We recommend you use one CT per phase; this will allow the zappi to show the total grid import and export figures rather than just one of the phases.

If all three phases are monitored and the generation is 3-phase, it is also possible to net the export power across phases, to do this, enable Net Phases in the Supply Grid menu see Supply Grid – Net Phases. This allows the zappi to use surplus power from any phase and not just the phase which the zappi is installed on. However, you must be sure that the electricity is metered in such a way as to allow this.

Battery Storage Systems

AC Coupled

Where there is an AC coupled battery storage system, there can be a conflict as both the storage system and the zappi are effectively competing to consume the surplus energy. Whilst this is not necessarily an issue, the results can be somewhat unpredictable.

There is the option to add an additional CT sensor to monitor the battery storage. This will give control as to which device has priority. The additional CT sensor should be wired to one of the CT terminals in the zappi or harvi device (if wireless measurement is required). This CT should be clipped around the live cable of the battery inverter with the arrow on the CT pointing away from the battery and towards the consumer unit/fuse board.

During the setup process it will be necessary to change the setting for the appropriate CT to AC Battery; refer to CT Config.

DC Coupled

Battery systems that charge directly from the solar array and cannot charge from AC are usually referred to as being DC coupled or Hybrid. This type of battery system uses the solar PV inverter to provide power from the batteries, thus it is not possible to differentiate between solar and battery power when using a CT to measure the AC current from the inverter.

Because of this limitation, there are less options for managing the surplus power with this type of battery system. It is usually possible to give priority to the battery by setting an Export Margin in the zappi. A setting of 50W or 100W is recommended. The Export Margin setting is found in the Advanced Settings/Supply Grid menu.


Third Party Diverters

Some properties may have a third-party energy diverter installed and you may want the zappi to take priority (when consuming surplus power) over the diverter. This is possible by installing an extra CT to monitor the diverter. The CT should be clipped around the Live cable of the supply feeding the diverter. The arrow on the CT should be pointing away from the diverter (towards the consumer unit). Wire the CT to the nearest myenergi device or use a harvi unit if a wireless connection is needed.

Configure the CT Type as Storage Only – see CT Config for details of how to configure CTs.

Voltage Optimisers

If there is a voltage optimiser (VO) installed in the property, the CT sensor and the zappi must both be on the same side of the VO; either the incoming grid supply or the optimised supply.