CEI EN 50341-2-20

General

EE.1 Application to new lines

In Estonia the standard EN 50341-1 (Part 1) can only be applied using this NNA (EN 50341-2-20) containing National Normative Aspects for Estonia.

This Part 2-20 applies to all new overhead electric lines with nominal system voltages exceeding AC 1 kV and also for low voltage (below 1 kV AC) overhead lines performed by aerial cables. The requirements of the structural design are applicable also for DC overhead lines, where the electrical requirements are given in the Project Specification.

EE.2 “New overhead line”

A “new overhead line” means a completely new line between two points, A and B. A new branch line of the existing power line should be considered as a new power line including the junction support. Specific requirements for junction support should be defined with the Project Specification.

Field of application

EE.1 Application to covered conductors and aerial cables

The standard includes requirements for the design and construction of overhead lines with nominal system voltages up to 45 kV AC equipped with covered conductors and aerial cables. Additionally, the requirements of the equipment standards and manufacturers’ instructions shall be followed.

EE.2 Application to mounting of telecommunication equipment

The Standard EVS-EN 50341:2013 is applicable to fixing of structural elements for telecommunication (antennas, All Dielectric Self Supporting (ADSS) equipment, junction boxes, etc.), if mounted on power line supports (towers), especially regarding wind forces and ice loads on such fixed elements. The design and installation should be done under the due control of the line owner and/or the competent authority. Mounting of telecommunication equipment on power line supports must be coordinated with the line owner and stated in the Project Specification.

This standard applies to telecommunication lines only in the case of their common installation with power lines. This standard does not apply to separately installed telecommunication overhead lines.

If telecommunication equipment (antennas, dishes, etc.) will be installed in the transmission line supports, and their size, location or mounting may have major effects on the loads or design of the structures, the requirements of EVS-EN 1993-3-1/NA:2009 shall also to be taken into account. If such structures include conductive parts, the requirements on clearances in subclause 5.8 should be applied.

EE.3 Application to installation of other equipment

Only equipment belonging to the line (electric or telecommunication line) can be installed on the overhead lines. However, with the permission of the owner of the line, equipment serving communal services or environmental protection like road signs, warning signs or warning balls, etc., may also be installed. The installation height of equipment meant to be installed and maintained by an instructed person shall be such that the work can be done without climbing the support and the distances of safe electrical work can be followed. The additional loads due to this equipment on the line supports shall be taken into account if necessary.

EE.4 Application to existing overhead lines

The Standard EVS-EN 50341:2013 shall not be applied to maintenance, branch lines, extensions or diversions of existing overhead lines in Estonia, unless specifically required in the Project Specification.

Overhead lines that meet the mechanical and electrical requirements in force at the time of their construction can be continually operated if this does not cause obvious danger. Such lines may be repaired and upgraded according to previously valid requirements. Thereat repair means replacing a damaged element with a similar new one; renovation means a more extensive improvement of the line with the aim of extending its life, while preserving the basic construction of the line.

Any modification of existing lines shall be subject to this standard, but previous norms and standards can also be used. It shall be made sure that the changes do not have a significant impact on the line's load. Modification means, for example, the relocation of some of the supports or the development of the line provided for in the initial design – for example, adding a circuit or reconductoring on existing supports.

In cases of major revisions of existing lines the degree of application of the Standard EVS-EN 50341:2013 should be in any case agreed upon by the parties concerned and specified in the Project Specification.

EE.5 Application to installations under construction or design

Installations in the design and construction stage may be completed by using the standard valid at the beginning of planning unless otherwise agreed with the line owner and/or any other competent authority.

It must also be determined in the Project Specification which previous Standard and to what extent shall be applied to the project in question.