For connection designers
Are you preparing an electrical design or assessment for a client regarding the implementation of a new connection or a modification to an existing one? On this page, you will find key points to consider during the design phase.
General information on connection design
It is advisable to begin the design process by determining whether the project involves upgrading an existing connection or if an entirely new electricity connection is required. The owner of the connection must order a new connection or a change to the connection capacity from us via an online form well in advance once the need is known.
If a new connection is not required and the existing connection capacity does not need to be increased, the necessary measures are often limited to modifications to the main distribution board and/or the connection cable. The electrical contractor of the site must notify us of any changes made to the property’s electrical installation using a general information form no later than four weeks before the desired implementation date.
We frequently receive inquiries about connection solutions for electric vehicle charging stations, as well as the possibility of having multiple connections on a single plot. At the customer’s request, a second or, if necessary, multiple connections can be provided.
In the case of multiple connections, the following requirements must be considered and verified by a qualified professional:
- The connections must be galvanically separated
- Each connection must supply clearly distinct and separate entities
- The entities supplied by different connections, as well as the connection cables, must be fire-separated
Design of a new connection
We recommend that the customer orders the connection as early as possible in the project so that the connection designer can take its implementation into account. We confirm the delivery time, connection point, and price in a connection agreement, which is sent to the connection owner. The fastest way to obtain information about the delivery time and connection point is to contact the connection owner directly.
Connection point
We define the connection point when processing the order and confirm it in the connection agreement. As a rule, the boundary of the plot serves as the connection point if no ready connection point exists at the time of ordering.
If a delivery time is specified in the agreement, confirmation of the exact location and technical implementation of the connection point must be awaited from Caruna’s partner contractor.
Using the plot boundary as the connection point means that, after the agreement is signed, we will construct—depending on the case and the connection size—the cable termination, distribution cabinet, or substation at the plot boundary. Our partner contractor will design the technical implementation and precise location at the plot boundary and will contact the customer or their representative during the field planning phase of network construction.
If a connection point already exists on the plot, it is used as the primary connection point, provided no changes to the network are required. We confirm the connection point in the agreement and recommend planning the route of the connection cable on the plot only after the connection point has been confirmed.
Short-circuit current
When dimensioning protections for the internal network of the connection, the recommended design short-circuit currents defined by Energy Finland (ET) must be used, even if the calculated short-circuit current at the time of design is higher. The supplying distribution network may change, which can also affect the short-circuit current. Check the design short-circuit current based on the main fuse size in our contractor guidelines via the link below.
Connection cable
The connection cable must be sized and installed in accordance with the requirements of the network company. As a rule, four-core cables (e.g. AXMK) are used and dimensioned according to the connection size. For new connections, the conductor cross-section must be at least 25 mm² aluminium or 16 mm² copper.
Design of a connection modification
We recommend that the customer orders the change to the connection capacity as early as possible in the project so that the connection designer can take it into account during planning. We confirm the delivery time, connection point, and price in a connection agreement, which is sent to the connection owner. The fastest way to obtain this information is to contact the connection owner.
Connection point
We review the connection point as part of processing the modification order and confirm it in the agreement. If necessary, we will reinforce the network up to the connection point if the existing network is insufficient. Please note that the connection point may need to be changed if the connection capacity and/or purpose changes significantly. This will be communicated separately in a supplementary connection agreement.
Connection capacity
The connection owner can check the current connection capacity in Caruna Plus under contract details. If the information is not visible, the ownership information has likely not been updated. Ownership changes can be easily reported using a form.
Connection cable
If connection cables are renewed as part of the modification, they must be dimensioned according to the standards and recommendations in force at the time of the modification.
Short-circuit current
When dimensioning protections for the internal network, the recommended design short-circuit currents must be used, even if the calculated value is higher at the time of design. The supplying network may change over time. Check the correct values in the contractor guidelines.
Connection data for electric vehicles or heating system changes
Detached house or holiday home
If you are assessing the adequacy of an electricity connection for a detached house or holiday home, contact an electrical designer or equipment supplier. If they require information about current consumption or connection details, these can be easily checked in Caruna Plus.
Terraced house or apartment building
If you are a consultant or electrical designer and need to determine available capacity (e.g. for a terraced house or apartment building) for cost estimation, please contact us via the form linked below. Please note that if you are requesting information on behalf of the connection owner, you will need a power of attorney.