Meters and metering cabinets

Caruna installs, maintains, and owns all metering devices and data communication connections required for electricity billing measurement. Caruna also ensures the reporting of measurement data to electricity market participants, as well as the stability of devices and compliance with replacement intervals.

The following standards and recommendations form the basis of this metering guideline:

SFS 2529 Meter mounting base

SFS 2537 Metering connections and numbering of terminals

SFS 3381 Metering equipment

SFS 3382 Control and remote metering equipment

ET 2022 Metering recommendation / ET Principles of electricity metering 2022

The customer is responsible for purchasing and installing, at their own expense, the in-direct metering transformers, meter bases, terminal blocks, fuses, and conductors required for metering.

For energy metering where the main fuse size is up to 63 A, directly connected remotely readable electricity meters are used. For sites over 63 A, indirect metering and instrument transformers are used.

The meter’s data communication connection is implemented by the network company using GSM/GPRS/UMTS or PLC communication, and hourly series are read from the meter. To maintain the communication connection, it is recommended to disconnect the mains using the I/O button on the meter. The recommended installation location for the meter in detached houses and holiday homes is between the main fuses and the main switch.

Load control

With electrical load control, an electric storage heating device, such as a water heater or storing floor heating, is switched on by a timer in the electricity meter.

Load control is automatically available to all customers who have night or seasonal tariff as their electricity transmission product and have controllable electrical devices connected to the electricity meter. When load control is activated for the first time, the switching time group is randomly assigned during commissioning from the basic control category. After commissioning, the customer can change the switching time group themselves via the Caruna+ mobile app.

If load control has not been previously activated, the customer’s electrical contractor installs the necessary connections for the controllable device to the electricity meter. The installation must be reported using the general information form, after which Caruna’s electrical contractor will activate the load control. If necessary, Caruna’s contractor will also install a new electricity meter if the old one does not have a load control relay.

Load controls are divided into four different groups, which switch on at different days on the hour between 22:00 and 24:00 or every day at 22:00 and switch off at 07:00.

* Table 1: Basic load control groups

Full night-time use

The full-night switching time is generally suitable for sites that require more time for heating electric storage devices during winter. For example, this could be a large electrically heated detached house with small fuses (25 A).

Load control is active from Monday to Sunday between 22:00 and 07:00 for nine hours, and the group identifier on the electricity meter is 4.

Optimizing night-time use

These switching times shift consumption to quieter night hours. The customer can choose the duration that best suits their needs. If the site’s water heater normally heats up in three hours, it is advisable to start heating only at around two o’clock at night. In that case, a five-hour heating period is usually sufficient.

The customer benefits most from these switching times if they have a night or seasonal transfer product and purchase electricity priced by the exchange or night rates.

Night-time switching times from Monday to Sunday are Group 5, Group 6, and Group 7.

The new load control groups introduced at the beginning of 2021 serve, for example, night electricity heating users and solar electricity producers.

Load control groups 8–15 are intended to direct surplus electricity produced by solar panels to heat, for example, a water heater.

Tariff control time

The customer’s product may be two-rate night transfer or seasonal transfer instead of single-rate transfer, meaning different tariffs apply at different times. This means that even though load control operates according to the load control group’s schedule, the tariff still switches according to the tariff schedule based on the customer’s product:

Night transfer times:

Day electricity Mon–Sun 07:00–22:00

Night electricity Mon–Sun 22:00–07:00

Seasonal transfer times:

Winter daytime between 1 Nov–31 Mar Mon–Sat 07:00–22:00

Other times between 1 Apr–31 Oct Mon–Sun and between 1 Nov–31 Mar Mon–Sat 22:00–07:00 and all Sundays

Electric heating

For electric heating, it is recommended to use the connection recommendations prepared by SLY 72/92 or equivalent options provided by switchboard manufacturers.

Heating control

The control contacts of the meters are generally 2 A or 100 mA. A separate night-control auxiliary relay must be installed in the sub-switchboard or in the metered section of the metering cabinet, which the customer purchases and owns.

In multi-meter cabinets, heating controls must be wired to each apartment’s meter individually. Heating control must come from the customer’s group switchboard. The control wiring must reach the metering cabinet via a terminal block to the meter.

Includes instructions for sizing and wiring instrument transformers for low-voltage measurements over 3x63 A as well as medium- and high-voltage measurements.

In indirect metering, screw or spring-clamp terminal blocks must be used. The terminals must be disconnectable from the screw-clamped intermediate terminal and have 4 mm test sockets on both sides. On the instrument transformer side, the terminals must also be capable of parallel connection.

For indirect metering, voltage and current conductors must have a cross-sectional area of at least 2.5 mm² unless the load/burden, short-circuit withstand, or voltage drop requires a larger size.

The type of instrument transformers is selected according to installation space requirements. If they are exposed to short-circuit currents and magnetic fields, voltage and current circuit conductors must be installed in separate metallic protective conduits or trays.

Terminal blocks are installed in a sealable space together with the billing meter. A working space of at least 50 mm must be reserved on both the input and output sides of the terminal blocks. Terminal blocks are installed horizontally and numbered according to wiring diagrams from left to right with consecutive numbers 1…n (currents 1–6, voltages and neutral 7–10).

Voltage and current circuits are separated by insulating plates placed in the terminal blocks. In switchboards with multiple indirect measurements, each measurement’s terminal blocks must be clearly identifiable for its own meter. Each indirect measurement must have its own phase-specific voltage fuses rated 2–10 A.

Customer devices are not allowed in the same measurement circuit as billing meters.

Meter bases

Meter bases must be marked by the contractor with the apartment number both in multi-meter cabinets and on the apartment’s distribution board before meter installation. Sequential numbering starts from the top left corner, row by row.

Meter bases must comply with standard SFS 2529 and use M2-type bases.

For indirect measurements: 1 x M2

For 1- and 2-rate measurements: 1 x M2

Meter bases must be installed so that the center of the meter frame is between 80–180 cm from the working level. For power meters, the corresponding height is 100–170 cm. There must be no door frames or wall structures in front of the meters, and a free working space of 80 cm must be maintained in front of the cabinet.

Multi-meter cabinets

Multi-meter cabinets are often used in apartment buildings. When a connection has multiple meters, they must be located in the same metering cabinet. Multi-meter cabinets can be located in several rooms. Free access for the network company must be arranged to the metering cabinet. If multi-meter cabinets are located in different rooms, the main cabinet must have instructions indicating where the meters are located. When ordering meters for multi-meter cabinets, the customer must provide Caruna with metering cabinet diagrams, riser diagrams, and an apartment list for creating and naming usage points.

The final apartment numbering on the meter frames of multi-meter cabinets must be clearly and permanently marked in the upper corner of the frames, either painted or with a label. The numbering must proceed row by row, starting from the top left corner to the right across the entire width of the cabinet or according to cabinet sections. Sequential numbering must be used throughout the site. For example, apartment numbering A1–D54; the same frame number must never be used in the same connection more than once. The numbering must match what the contractor or builder has reported to Caruna and what has been used to create the usage point in our customer information system. Apartment numbering must not be changed later without agreement with Caruna.

It is recommended to build the metering system so that load control features enable usage-point-specific load control. This should be especially considered when constructing or renovating multi-meter cabinets.

Casing

Standard-compliant casing is used for metering spaces. The Meter can also be located in the main switchboard.

Meter cases must be equipped with hinges if indirect metering is used. The viewing window and cover must be sealable. A 16 mm² PE conductor must be brought into the meter box and connected to the building’s grounding bar.

Almost all electricity meters in detached houses allow real-time energy pulse output to be connected to the customer’s own system. If the site has small-scale production, pulse output is not recommended because S0 pulses from NES/Echelon meters cannot distinguish between consumption and production.

Pulse output (kWh) can be wired to the following direct and indirect meters with a pulse connector: Landis+Gyr E650/E550 and NES/Echelon meters with type 83X3X-3IHA(X), e.g., 83332-3IHAH or 83522-3IHA (H = pulse connector). The direct NES 83334-3IKBAA meter also has a pulse connector.

Pulse output contacts in Landis+Gyr meters are potential-free; indirect E650 meters provide active and reactive energy pulses in both directions.

To enable pulse output, the customer’s contractor brings clearly marked pulse wires to the meter and orders the pulse wire connection to the customer’s equipment using the general information form (YTL). After this, Caruna’s contractor connects the wires to the meter and seals the meter.

Pulse connection and the installer’s visit are chargeable, and the customer is billed a one-time fee according to our service price list. If the meter does not have a pulse output, the contractor can order a meter replacement with pulse connectors using the same general information form, according to the service price list.

Switchboards, enclosures, junction boxes, main fuses, and similar devices and components that contain unmeasured electricity for the consumer must be reliably sealable. Examples of such devices and components include:

• Terminal covers and lids of energy meters
• In-direct measurement transformers and their enclosures
• Measurement terminal blocks and their enclosures
• Voltage fuse casing or a unified cover
• Decommissioned tariff control fuses
• Connection cable junction box, main fuse casing, and main switch                          

No consumer installations or PE and N busbar connections are allowed in sealable spaces. It is recommended that no unrelated conductors be routed through sealable spaces to other parts of the switchboard.

If the seal is broken, always contact Caruna’s contractor service.