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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 first rolled out in 2018, known as SMETS 2.

SMETS 2

This specification is more advanced. A more modern communication network is used with these meters and all suppliers will use this - keeping your smart meter smart when switching suppliers.

To understand the progress and factors affecting the roll-out of these meters see the page on Meter Roll-Out.

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.

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. Some 700 communication towers communicate directly with smart meter Communications Hubs in homes using the 400MHz band.

By 1^st June 2020 Arqiva Limited had achieved their maximum contracted 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 (Virgin Media O2) in the rest of England and Wales, known as the Central & South regions. This system is commonly used by mobile phones. In a cellular system, geographical areas are divided into regular shaped "cells".

Additionally, Telefónica also use aerials and local mesh networks to improve coverage. A mesh uses other comms hubs in meters around you to reach a comms hub with a radio link to 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.

By 1^st January 2021 Telefónica had achieved their maximum contracted 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 impacts the service provided by Telefónica (Virgin Media O2) for Smart Meter communications in 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 achieve this DCC plan to have 4G single band Communications Hubs available in 2023, with dual band to follow in Q2 2024.

4G connectivity for the smart meter network will be provided by Vodafone who have signed a services agreement with DCC. The agreement, signed in 2023, is to build and operate a 4G managed network for up to 15 years.

The Telefónica and Vodafone services will run alongside each other as the Smart Meters are transferred to the 4G service.

SMETS 2 Meter Models

Nearly all meters 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.

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 - Gas Meter Battery

SMETS 1 and 2 gas meters are powered by a battery, as it would be dangerous to power them from the mains electricity supply.

The lithium battery is expected to last between 10 and 15 years, although this can vary greatly depending on the battery demand. To keep demand low the gas meter only talks to the communications hub every 30 minutes, although the demand on the battery increases greatly if firmware updates are downloaded.

When the battery is low some meters may show an indication on the screen, and some may omit a short beep. They do also send an alert to the supplier to let them know the battery is getting low, but unfortunately suppliers do not usually act on this due to lack of monitoring systems and poor maintenance policies - their focus is on new installations.

If you see that your gas meter battery is dead let your supplier know.

When the battery is dead the gas meter will stop recording and the supplier will make estimates for billing.

The gas meter battery cannot be replaced by the customer but must be replaced by the supplier or their agents. In practice suppliers usually swap the gas meter for a new one rather than replacing the battery.

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.

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

You can see on the table above that the Toshiba comms hub used in the Central & South Regions can take one or two aerials. The SKU2 and SKU3 comms hubs have an additional cover on the left over the aerial connectors.

Surveys have determined in advance what equipment and aerials should be used for an installation.

In the Central & South region if the WAN does not operate with the recommended equipment the installer will work through the following equipment combinations:

1. SKU1 comms hub
2. SKU2 comms hub and T1 aerial
3. SKU2 comms hub and T2 aerial

If it still doesn't work, the installer will leave the SKU2 comms hub with the T2 aerial installed and report to DCC that additional WAN work is needed. This is known as "Install and Leave" in the industry.

T1 and T2 aerials are for internal use only. Typically, the smaller T1 aerial will be used to get around obstacles, and the T2 for signal strength issues.

T3 aerials are for external use where there are signal strength issues.

The table below shows details for each of type of aerial.

The tables below show the different frequency bands used by Smart Meter Comms Hubs.

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 was made available from February 2022.

CHAS = Communication Hub Antenna Structure,
CSP = Communications Service Provider,
DBCH = Dual Band Comms Hub,
SBCH = Single Band Comms Hub.

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.

SMETS 2 Accessories

As we hear of Smart Meter installation accessories we will add them to the table below.