SMETS 2 Meters

Types of Smart Meter

There are two main types of smart meters – the older models known as SMETS 1 (Smart Meter Equipment Technical Specifications) and the newer versions that were rolled out in 2018, known as SMETS 2.

This specification is more advanced and meters were first rolled out in 2018. A more modern communication network is used with these meters and all suppliers will use it this – keeping your smart meter smart when switching suppliers.

Wide Area Network

The Smart Metering Wide Area Network (SMWAN or WAN for short) is the name given to the communications network between the communications hub sitting on top of your electricity meter and the company responsible for collecting the data and passing it on to other businesses such as suppliers. This company will usually be the Data Communications Company (DCC) which the government has set up especially for the role of supporting SMETS 2 meters. Depending on the Communications Service Provider (CSP), which varies by areas of the UK, the technology can change depending on what works best in a local area. Sometimes your comms hub will communicate directly with DCC and sometimes it will talk through other comms hubs around you to reach a particular comms hub which has direct communications with DCC. This form of communications looks like a mesh when you draw out the possible links between meters and is therefore known as a Mesh network.

UK WAN coverage map

Scotland and the North of England

Long-Range Radio communications (LRR) is used by Arqiva Limited in Scotland and the North of England. The LRR system uses infrastructure and technology similar to that already used for other important national communications networks, such as those for emergency services and keeping lifeboat stations connected. Communication towers communicate directly with smart meter Communications Hubs in homes.
By 1st June 2020 Arqiva Limited had achieved their maximum contacted coverage of at least 99.5%, achieving 99.55%.

Rest of England and Wales

The 2G/3G cellular radio communications network is used by Telefónica (O2) in the rest of England and Wales. This system is commonly used by mobile phones. In a cellular system, geographical areas are divided into regular shaped "cells".
Additionally Telefónica also use local mesh networks to fill in the mobile coverage gaps.
By 1st January 2021 Telefónica had achieved their maximum contacted coverage of at least 99.25% in the Central and South Regions, achieving 99.25%.

2G and 3G networks to close by 2033

The government and UK mobile network operators have agreed to phase out 2G and 3G mobile networks by 2033 in order to free up bandwidth for 5G and future 6G services. This includes Telefónica (O2) who provide the Smart Meter communications for the Central and Southern regions of the UK.

This change will require the replacement of communications hubs on the Smart Electricity Meters in the Central and Southern regions of the UK. To this end the DCC plan to have 4G single band Communications Hubs available in 2023, with dual band to follow in Q2 2024.

SMETS 2 Meter Models

Nearly all meter being currently installed are SMETS 2. If you are wondering if you have a SMETS 2 meter, look up your meter model number in the table below which lists all currently approved SMETS 2 meters.

List of SMETS 2 Meter Models
Manufacturer Model ESME / GSME Type
Aclara SGM1415B ESME 5 terminal
Aclara SGM1416B ESME 5 terminal
Aclara SGM1422B ESME Twin Element
Aclara SGM1411B ESME
Aclara SGM1412 ESME
Aclara SGM1412B ESME
Aclara SGM1431B ESME Polyphase
Aclara SGM1432B ESME Polyphase
Aclara SGM1433B ESME Polyphase
EDMI ES-12B ESME 5 terminal
EDMI ES-30B ESME Polyphase
EDMI GS-60A GSME Ultrasonic
EDMI GS-60B GSME Ultrasonic
Flonidan G4-6UDZV-2 GSME
Flonidan G4SZV-1 GSME Diaphragm
Flonidan G4SZV-2 GSME
GWI G4-MG-SE-GM-V2 FVI GSME Diaphragm: Front Viewing Index
GWI G4-MG-SE-GM-V2 TVI GSME Diaphragm: Top Viewing Index (for semi-concealed applications)
GWI G4-MG-SE-GM-V2 DB FVI GSME Double Band, Diaphragm, Front Viewing Index
GWI G4-MG-SE-GM-V2 DB TVI GSME Double Band, Diaphragm, Top Viewing Index
Honeywell AS302P ESME
Itron EM425-UK2 ESME
Itron FGBB03 GSME Ultrasonic
Kaifa MA120 ESME
Kaifa MA120B ESME 5 Terminal
Kaifa MA329B ESME Polyphase
Landis & Gyr E470 ESME
Landis & Gyr E470-5394 ESME
Landis & Gyr G470-672 GSME Ultrasonic
Landis & Gyr G470-682 GSME 868MHz
Secure Liberty 101 ESME
Secure Liberty Gas 200 GSME

ESME = Electricity Smart Metering Equipment
GSME = Gas Smart Metering Equipment.

Five terminal electricity meters have an additional live connector for an off-peak load switched by a timer. The other four terminals are live and neutral in, and 24 hour live and neutral out.

Diaphragm type gas meters have been used for many years. Within the meter there are two or more chambers formed by movable diaphragms. With the gas flow directed by internal valves, the chambers alternately fill and expel gas, producing a nearly continuous flow through the meter. As the diaphragms expand and contract, levers connected to cranks can link to a counter or provide an electrical pulse to measure the gas volume.

Ultrasonic gas meters measure very small difference in time that it takes an ultrasonic pulse to travel with and against the flowing gas stream. A microprocessor can then calculate the gas used. The main advantages of ultrasonic gas meters are that they have no moving parts and are therefore more reliable, and they are more accurate than conventional gas meters.

Semi-concealed gas meters are installed against the outer wall of a building and partially buried into the ground.

SMETS 2 Communications Hubs

The communications hub fits on top of the electricity meter and is owned by the DCC, unlike the meter which is owned either by your supplier or a MAP (Meter Asset Provider) to whom your supplier pays a rental charge. The interface connection to the meter is called the Intimate Communications Hub Interface (ICHI).The comms hub provides both the WAN and the HAN. The Wide Area Network talks to the DCC and the Home Area Network talks to the gas meter and the IHD.

Different comms hubs are used in different regions, see the table below.

SMETS 2 Comms Hub Variants
CSP Region WAN Variant Manufacturer Comms WAN Technology External Aerial Port
(Arqiva Limited)
Standard 420 EDMI Long Range Radio No
Variant 450
Central & South
SKU1 Cellular WNC (Wistron NeWeb Corp.) & Toshiba Cellular
SKU2 Cellular + Mesh Toshiba Cellular & Mesh 1 Cellular
SKU3 SIMCH Cellular & Mesh 1 Cellular
1 Mesh

SKU = Stock Keeping Unit
SIMCH = Special Installation Mesh Communications Hub.

You can see on the table above that the Toshiba comms hub can take one or two aerials. Surveys have determined in advance where these will be used. The table below shows the purpose of the different aerial types.

SMETS 2 Aerial Types
Aerial Type % Installs Radio Use Manufacturer Dimensions (mm) On which Hubs
Low Gain
6% Cellular Panorama 165 x 32 x 20 Toshiba SKU2
(and SKU3 if poor signal)
Low Gain
WNC 128 x 25 x 17
High Gain
4% Panorama 372 x 33 x 20
High Gain
WNC 320 x 41 x 17
High Gain
0.5% Panorama 695 x 25 x 25 Toshiba SKU2/3
High Gain
Oriel 580 x 100 x 40
0.25% Mesh TBA Toshiba SKU3
0.25% TBA
No aerial 89%

The table below shows the different frequency bands used.

SMETS 2 Frequency Bands
Frequency Band (MHz) CHAS WAN / HAN CSP Area
WAN (includes 'buddy mode') North excluding Fylingdales
WAN (includes 'buddy mode') North at Fylingdales
HAN North, Central and South
WAN MESH Central and South
WAN Central and South
2100 WNC DBCH,
WAN Central and South
2400 All CHAS Units HAN North, Central and South

CHAS = Communication Hub Antenna Structure,
CSP = Communications Service Provider,
DBCH = Dual Band Comms Hub,
Fylingdales (Fyl) = RAF radar base where frequency interferes with normal Smart Meter communications,
SBCH = Single Band Comms Hub.

The Variant 450 comms hub for the North at Fylingdales is expected to be first available in February 2022.

What do the indicators mean on a SMETS 2 Comms Hub?

On the front of a comms hub there are a series of LED indicators showing the functional status of the metering system. Each LED has a legend as shown below:

CSP Region - Central & South

SW - Software
This shows the status of the hub's software.
WAN - Wide Area Network
Shows your communication hub's ability to communicate with the DCC and your supplier.
MESH - Mesh Communications Network
This light will be on if your meter is communicating through the Mesh network. It will be off if your meter is only using the normal WAN to communicate. The Mesh network has been built to allow more meters to communicate in areas with poor or no WAN signal.
HAN - Home Area Network
This light shows the connection status of your electricity meter, gas meter and IHD with your communications hub on the HAN.
GAS - Gas Meter
This light tells you if a gas meter is connected to the HAN. If you don’t have a gas meter installed this light will be off.

CSP Region - North

WAN - Wide Area Network
Shows your communication hub’s ability to communicate with the DCC and your supplier.
HAN - Home Area Network
This light shows the connection status of your electricity meter, gas meter and IHD with your communications hub on the HAN.

What does the flashing rate mean?

The frequency of flashing relates to the status of the function as follows:

  - Power Up
LEDs are shown without flashing for 10 seconds after power up to allow the operator to see that all LEDs are working.
  - Normal
A slow flash rate of 1 flash per 5 seconds means that the process is in its normal state.
  - Transient
A flash rate of 1 flash per 2 seconds means that the process is in a transient state such as making a communications connection.
  - Error
Fast flash rate of 2 flashes per second means that there is an error. Call your supplier if this does not change after 48 hours.
  - Off
The communications hub is powered down.
(Page updated: 2022-03-25)

Questions & Answers

What is the accuracy of Smart Meters?
Smart Meters have to be approved under UK law to a certain accuracy. The accuracy is defined as the MPE (Maximum Permissible Error) class.
  • Electricity Meters: MPE Class A
    • ± 2.5% at 1 amp
    • ± 2.0% at 20 amps.
  • Gas meters: MPE Class 1.5
    • ± 3%
Many electricity meters fitted achieve the higher standard of MPE Class B (± 1.5% at 1 amp and ± 1% at 20 amps).
All meters will have the accuracy class printed on their front face. (Updated: 2022-01-16)

Are smart meters safe?
Yes. Smart meters are subject to the same safety regulations and testing of any in-home technological devices, including baby monitors and mobile phones. Additionally the meters are secure having a security system developed by industry and government experts including GCHQ's National Cyber Security Centre. A side benefit is that many safety problems are being spotted in peoples homes during installation of the smart meter which would not have been spotted without a visit. (Updated: 2019-10-21)

What is a SMETS2 meter?
Over ten million meters have now been installed to the Smart Metering Equipment Technical Specification (SMETS) 2 standard. These are the most advanced meters available and communicate through the Data Communications Company (DCC). Suppliers were obliged by government rules to stop installing SMETS1 meters by 15 March 2019 and only install SMETS2 meters. Suppliers started to install SMETS2 meters in Q2 2017 and in large volumes from autumn 2018. (Updated: 2021-12-12)

How are they tested for accuracy through their life?
Smart meters fall into the MID scheme (Measuring Instruments Directive) which means they are certified at their introduction to market as being accurate but are not given a certification period as traditional meters used to be. Their life depends on their performance during MID In-service testing (IST). The Office for Product Safety & Standards gathers samples of meters from suppliers, if they prove to be in-accurate that type/age of meter will be replaced in customer premises. (Updated: 2019-08-23)

Can my supply be turned off remotely?
Smart meters have the facility to remotely disconnect and reconnect both the electricity and gas supply. However, most suppliers seem to have decided it is too dangerous to remotely disconnect or reconnect, as in the case of disconnection they cannot always be sure that the customer isn't relying on a supply for serious health reasons and in the case of reconnection the customer may have left a cooker on for example. (Updated: 2015-01-23)

How much data is stored on a Smart Meter?
The SMETS2 specification requires the following data to be recorded and stored.
Half-hourly electricity data:
  • 13 months of consumption (Active Energy Import)
  • 3 months of active energy exported
  • 3 months of reactive energy imported
  • 3 months of reactive energy exported.
Gas data:
  • 3 months of half-hourly consumption
  • 13 months of monthly consumption.
(Updated: 2020-11-07)

Do Smart Meters use 5G?
No Smart Meters currently use 5G. Even in the future a move to 5G is unlikely as the amounts of data transferred are very small and long distance communication is the main requirement. 5G is a higher frequency technology and generally low frequencies are most reliable and capable of penetrating obstructions like buildings, which is why 4G will often work in more places than 5G. Higher frequencies are also more easily scattered by objects. (Updated: 2021-04-07)

Can I lay a cable to help join the devices together?
The meters and IHD (In Home Display) can only be joined through a radio link. This applies to all three standards of meters pre-SMETS, SMETS1 and SMETS2. However, one or two suppliers may be able to offer a zigbee booster, this is similar to the wireless booster you can buy for your home broadband and just plug into a power socket.
Our recommendation would be to let your supplier sort it out, as a communications hub (868MHz) with better reach will be available to suppliers to install with SMETS2 meters where needed from mid 2020. (Updated: 2020-02-09)

What is the gas mirror?
Communications from the comms hub on the electricity meter to the gas mater can be slow and may drop out sometimes. To make the system more efficient the engineers came up with the idea of a "Gas Mirror" which is to keep a copy of the gas meter software in the comms hub.
Any changes such as new firmware destined for the gas meter are transferred to the "Gas Mirror" first and then sent to the gas meter over time. (Updated: 2020-10-24)

Can smart meters be upgraded?
Smart meters can have a firmware upgrade just like your computer or mobile phone. The upgrade will be used to fix faults and add new functionality and should be carried out in the background with little impact on the customer. Indeed this feature is being used to allow SMETS1 meters to be upgraded for the SMETS2 systems; this will allow them all to interoperate. (Updated: 2019-10-21)

How does the smart meter record energy generation if a solar panel is installed?
All smart meters will record the export and import separately, and you will be able to see the readings by stepping through them on the meter display. All the meters should show all 4 power quadrants. You can ignore the reactive ones and just look at active import and export.

Power quadrants:
  • Active energy import (Wh) - this is what we are billed for normally
  • Reactive energy import (varh)
  • Active energy export (Wh) - this is your useful export power
  • Reactive energy export (varh).
The bad news is that many companies have not set up their systems to automatically collect or use the export information, as it would have taken time and money they don't have for such a low volume user base. (Updated: 2018-10-02)

What is dithering?
When a Smart Meter loses power and powers up it sends an alert message to suppliers and network operators to let them know. If a large area had lost power and thus a large number of meters were to send these messages at once it would put a heavy load on the communications network. To prevent this the meters "dither", that is to say they all wait a short random period before sending those first messages thus avoiding the simultaneous peak. For the first two years (to September 2018) the dithering period was up to 2 minutes. After that a decision will be made on whether to set it to the default 5 minutes. (Updated: 2016-02-16)

How often will my IHD be updated with data from my meters?
Your IHD (In Home Display) will be updated by your electricity meter about every 10 seconds and by your gas meter about every 30 minutes. The gas meter updates less often in order to preserve its battery life which in normal use is expected to be at least 10-15 years. (Updated: 2020-10-23)

My supplier says my signal is too weak?
Smart meters communicate through mobile communications and so the signal strength is an important factor to consider for installation.
For SMETS1 meters the installer will usually test on site and make a decision there and then whether to install. If there is not a sufficient signal they will usually walk away.
For SMETS2 there are more options. The communications are provided by the Data Communications Company (DCC) and suppliers can check that a premises has communications before visiting a site. Once on site they can check with a signal checking device if the signal is strong enough in the meter location. If it isn’t they can fit a number of different aerials to try to boost the signal. If that doesn’t work an external aerial or an alternative mesh communications method is available in some areas. Even then they can leave the meter de-commissioned and ask the DCC to get the communications working. (Updated: 2017-02-01)

Can I fit an aerial?
You cannot fit an aerial yourself. All Comms Hubs and Aerials for Smart Meters have to be supplied via approved channels and can only be installed by authorised engineers. In fact attempting to install one yourself will trigger the tamper alarm on the meter which could mean a chargeable visit from your supplier. (Updated: 2021-11-16)

Are the meters battery powered?
The electricity meter is mains powered but the gas meter is battery powered. The gas meter battery can be replaced by a Smart Meter Installer and is excepted to last the life of the meter (10 to 15 years), however, its life can be greatly reduced heavy communications such as repeated firmware updates. (Updated: 2016-01-27)

Do smart meters work with home generated renewable energy?
Traditional meters are only capable of recording consumption and consequently don't take into account any energy generated by a household. If you have or are planning to install solar panels or any other renewable energy generating system in your home, a smart meter will enable you to measure how much energy you produce. The smart meter will also calculate whether or not there is a surplus which you could sell back to the grid.
However, as this is not a common requirement suppliers have been slow in implementing systems to support it - you will have to shop around for the supplier which can support your requirements. (Updated: 2019-10-21)

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