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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 called the Wide Area Network, 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 Meter Roll-Out.

Number of SMETS 2 Meters

By 28^th February 2026 25,978,440 SMETS 2 meters had been successfully installed and set up in DCC's systems.

Additionally, by the same date, some 11,507,686 SMETS 1 meters were operating through the DCC's systems following migration from their original control systems.

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.

2A Aux means the meter has a auxiliary control circuit rated at a maximum of 2A. The rating is too low to control heating loads directly so this auxiliary control must be fed into a Contactor.

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.

Five terminal (5T) electricity meters have an additional live connector for an off-peak load switched by an internal timer. The other four terminals are live and neutral in, and 24 hour live and neutral out.

Four terminal (4T) electricity meters are the most commonly used meters. The four terminals are live and neutral in, and live and neutral out.

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

Seven terminal (7T) will be twin element or dual rate electricity meters with an additional live connector for an off-peak load switched by an internal timer.

Thermal Mass meters measure the amount of gas used by monitoring the cooling effect of gas on sensors.

Twin Element or Dual Rate meters can measure the load in different circuits independently, meaning load can be measured for two different price rates at the same time. Usually, one circuit will be for normal domestic load and the other for heating.

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 Diaphragm gas meters.

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 20 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 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 using the mobile network 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.

If the mobile network Communications Hub does not connect to the WAN successfully 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.

CSP Region - North Only

For the North Region, Communications Hubs will indicate their current operational status via two LED indicators which are bi-colour (green and red).

WAN - Power and Wide Area Network

Shows your communication hub's power and its ability to communicate with the DCC and your supplier. Green means it is operating normally.

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. Green means it is operating normally.

All CSP Regions - 2G/3G

For Communications Hubs using mobile communications 2G/3G, Hubs will indicate their current operational status via five LED indicators.

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.

All CSP Regions - 4G

For Communications Hubs using mobile communications 4G, Communications Hubs will indicate their current operational status via five LED indicators.

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.

PWR - Device power

This light shows if the communications hub is powered up.

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.

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 every 5 seconds means that the process is in its normal state.

  - Transient

A flash rate of 1 flash every 2 seconds means that the process is in a transient state such as making a communications connection.

  - Error

Fast flash rate of 2 flashes every 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.

Even more information can be found in these documents provided by DCC.

SMETS 2 Accessories

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

Manufacturer: Kaifa

Model: FL-100

Type: Flying Lead

Description: Module to fit on top of the electricity meter providing a cable to allow the Comms Hub to be fitted nearby.
Useful when there is limited space above the electricity meter or where the comms hub needs to be moved a short distance to improve the signal.
The FL-100 Flying Lead can be ordered in two lengths, 0.5m and 1.5m.
(Used by Octopus in Scotland.)