Network safety

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Electricity network gives you safe access to electricity

The safety of the electricity network and safe work in the vicinity of the network are an inherent part of our operations. We build and maintain our electricity network so that it does not cause hazards to our customers or the environment. Read more about the common safety considerations related to electricity networks. If you have any questions about safety, please contact our experts directly via our customer service.

Electricity produced by power plants is transferred to the main electricity network where the voltage is 110, 220 or 400 kV. The substation converts the voltage to a voltage suitable for the distribution network. In a medium-voltage network, the voltage is usually 20 kV. The voltage is converted further to 400 V at a distribution substation for distribution to homes connected to the low-voltage network. Homes are connected to the low-voltage network by a connection cable, which transfers power to the main distribution board. The main distribution board then distributes the electricity in accordance with the life and comfort requirements of the home.

Get to know the electricity network

This page contains information about the common structures of an electricity network so that you can recognise them and know how to act in a safe way in their vicinity. Please remember that in no circumstances should you touch electric wires.

Elenia Säävarma electricity network

The electricity network comprises both overhead lines and underground cables. Underground, the electricity network is safe from storms, thunder and heavy snowfall. What’s more, the weatherproof electricity network is environmentally friendly and safer than overhead lines. Removing overhead lines and pylons frees land for forestry and agricultural use. Before starting excavation, please find out the locations of underground cables to avoid causing damage to underground cables or creating safety hazards.

High-voltage open wire 110–400 kV

110, 220 and 400 kV wires are high-voltage wires. The national main grid uses 110–400 kV wires. In addition, 110 kV wires are also used for regional power transmission. High-voltage wires transfer electricity over long distances from power plants to closer to consumption centres.

110–400 kV open wires use different pylon structures. The pylons used outside urban areas are of the guyed, bipedal, gate-shaped type. The pylons used in urban areas are free-standing lattice masts. You can tell high-voltage wires by the length of the insulator chain and the number of insulator plates.

Wire voltage	Length of insulator chain	Number of insulator plates	Vertical distance to ground/road
110 kV	approx. 1 m	6–8	6 m/7 m
220 kV	approx. 2 m	10–12	6.5 m/7.5 m
400 kV	approx. 4 m	18–21	8 m/9 m

Medium-voltage overhead line 20 kV

Open wires are used in distribution networks for local power transmission between substations and distribution transformers. The construction of an open wire comprises a metal phase conductor attached to insulators on a beam. Another type of wire that is used is PAS, which is an open wire covered by a thin layer of plastic. The conductors are located closer to each other than in an uncovered open wire. The distance of the wire is at least 5 m from the ground and 6 m from the road. Outside urban areas, you can see 20 kV overhead lines near roads, usually on wooden pylons. The image shows a 20 kV open wire.

Low-voltage AMKA wire 0.4 kV

Low-voltage wires are used in the vicinity of settlements and in the lighting networks near roads and running paths. AMKA refers to a bundle assembled aerial cable, where the phase conductors insulated with black plastic are wrapped around a metal wire acting as a support cable. You can tell an AMKA cable by its twisted structure, which separates it from a straight telephone line. The height of the wire is at least 4 m from the ground and 5.5 m from the road.

Pole-mounted transformer

A distribution substation converts the 20 kV voltage to a 0.4 kV voltage suitable for customers. You can commonly see pole-mounted transformers in the overhead line networks used in sparsely populated areas. Pole-mounted transformers can rest on one or two pylons. In conjunction with laying the underground cables of the Elenia Säävarma electricity network, we will dismantle the pole-mounted transformers with the overhead line network and replace them with kiosk-style transformers.

Kiosk-style transformers

We will replace the dismantled pole-mounted transformers with kiosk-style transformers, which protect the transformers from extreme weather, small animals and birds. Kiosk-style transformers are also environmentally friendly because they include reservoirs for potential oil leaks. Kiosk-style transformers are used in urban areas and increasingly also in sparsely populated areas.

Substation

An essential part of the electricity network, substations convert the voltage level used for power transmission into a lower voltage. Usually, the voltage is converted from 110 kV to 20 kV. Substations include network protection and automation systems, which ensure the safety of the electricity network and uninterrupted electricity distribution. With the construction of a smart electricity network, the level of automation will also increase in other parts of the distribution network. Substations are located inside enclosures, where access is prevented for safety reasons.

Link box

Part of the low-voltage electricity network, link boxes are most commonly used in underground cable networks. They are a common sight in urban and residential areas, where they distribute electricity to end users. Link boxes are installed in easily accessible places to enable unobstructed access for repairs or maintenance.

Are you planning to dig in the vicinity of an electricity network?

Make sure there are no underground cables on the excavation route!