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CAT A Code

A serious incident that will be reported to Distribution by phone and our engineer remains on site until DNO attend.

CAT B Code

A condition report which relates to a system fault or other dangerous occurrence on Distribution owned equipment. It is instructed via an industry D0135 data flow and the job will likely be aborted.

CAT C Code

A report to Distribution of a concern with the equipment which does not require urgent attention and is unlikely to stop the job from going ahead.


Metering systems are categorised by 7 measurements classes. There are different processes invoiced when moving between these measurement classes;

CT Meter (LV power down not required)

A Current Transformer is used to reduce the level of current from hundreds or thousands of amps to a lower level for the meter to record. The meter is configured to scale this proportion back to the original levels in order to accurately record the actual consumption on site. As the meter is not directly connected to the load, it allows larger sites using more energy to be safely metered as the meter is recording only a proportion of the total energy, before applying the multiplier to return the value to its original level. Most CT’s are rated to 5 amps – for example a CT rated as 100/5 will mean that for every 100 amps of current 5 amps will be passed through the meter, recorded and then multiplied by a factor of 20 (i.e. 100/5) to return to the original value.



Fault Investigation has been carried out and a report on an action taken is being made or a request for a decision on next course of action.


Cumulative readings and maximum demand readings.


Acknowledgement of appointment and terms or renewal of contractual terms.


The System Fault Information Centre is informing the Supplier and MOp of the outcome of an investigation into a report of a Category A report by telephone, or a Category B report by a D0135 flow.



A report to the DNO of a concern with the equipment which does not require urgent attention.



Request is being made and information provided to allow removal, replacement or installation of a meter.


Notification to a MOp or DC of any change to relevant Agent appointments and/or terminations for the metering point for the three functional processes: new connection, change of supplier and change of agent(s).



This flow notifies mapping of physical registers to time pattern regimes.


Meter technical details for Non Half-hourly.


This is a notification of a new or changed appointment to a metering system and of the contractual terms to be applied.


On appointment or change of agent appointment, metering system related details are requested to be transferred.



Notification that a meter could not be installed or a system energised due to faults or access problems.


Rejection of appointment and terms of renewal of contractual terms.



Meter Technical Details for Half Hourly.


The Supplier will inform the participants of customer contact address and mailing address details.



Communications and security information to accompany NHH Meter Technical Details for AMR Meter Types.


Notifies how a smart meter is configured.

Dual Band Communication Hubs (DBCH)

These devices communicate with each other via a Home Area Network (HAN) which is generated by the Comms Hub. These are called Dual Band Comms Hubs. They use a HAN frequency of 868MHz along with the existing 2.4GHz frequency. Dual Band Comms Hubs (DBCH) are expected to increase coverage to 96.5% of premises.


Gas and Electricity meters communicate to a communication hub through a Home Area Network (HAN). HAN communicates with the In Home Display (IHD), update every 10 seconds for electric and 30 minutes for gas, to display energy use for the consumer to review.

HV (Power down not required)

A Voltage Transformer is also used to precisely reduce the level of voltage from thousands of volts to a lower level for the meter to record and allow safe working by the meter operator without isolating supply. The meter is configured to scale this proportion back to the original levels in order to accurately record the actual consumption on site. VT’s are rated to the supply voltage of the distribution network (3.3kV, 6.6kV, 11kV, 33kV, 66kV, etc) and they step the voltage down at a ratio to 110v, so on a ratio 11000v:110v if the network voltage is 11kV the VT will output exactly 110v to the meter and recorded and multiplied by a factor of 100 to return to the original value. HV CT meters are 3phase meters specially for HV supplies and are normally for larger supply capacity sites and often in a HV area so require technicians with a higher skillset to complete the work.

Profile Class

A Profile Class is a classification of profiles which represents an exclusive category of customers whose consumption can be reasonably approximated to a common profile for settlement purposes.


A public switched telephone network is a secure method of remote data communications, using a PSTN modem connected to your existing PSTN line. Resulting in high data completeness and high success rate, this solution is compatible with most EDMI and Elster Meters.


Standard Settlement Class/Configuration: A definition of how a NHH meter is configured for settlement. Defines how many registers and the times that the registers record consumption.



A wide area network (WAN) is a telecommunications network. Comms Hub communicates to the DCC through a Wide Area Network (WAN), managed by Communication Service Providers (CSPs) and a Data Service Provider (DSPs).

WC Meter (LV power down required)

Whole Current meters are where all of the load passes through the meter. They are also sometimes described as “Directly Connected” and are used on Low Voltage (LV) sites. In order to replace the meter safely the site will always need to be powered down. WC Meters can be used on either Single or 3phase supplies.

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