Case Study

Case Study

Great blowing-in success in Europe's highest valley.

Even the experienced EE Energia Engiadina installers were astonished: in the high valley of Grisons canton, Switzerland, an astounding blowing-in distance has been achieved.

A home office in the mountains thanks to fast fibre optic connections – and to top it off, in the idyllic Engadine, one of the highest inhabited valleys in Europe and more than 80 km long. An idea which, thanks to the joint venture involving Swissgrid AG, Engadiner Kraftwerke EKW and EE Energia Engiadina, should become reality in the future.

The positive properties of the high-quality, new material PE-HD RAUSPEED microducts, tested with a sustained internal pressure test, demonstrated their capabilities in the summer of 2018 while blowing in the fibre-optic cable: following a winding course, the Vetter Minijet blowing device injected an 8.1 mm fibre optic cable into the installed RAUSPEED 16x2.0 at a blowing-in pressure of 14 bar – and achieved an impressive blow-in length of 5.23 km without any intermediate blowing. This far exceeds the average distance of 1–2 km in the backbone and 600–800 m for a house connection, for which installers usually opt for safety reasons. And as if that's not enough – in addition, the route passed beneath the Inn River and, because of shafts, a permanent connector every 800m.

After Swissgrid AG and EKW had cleared the way for the expansion of the high-voltage power line early in 2013, EE Energia Engiadina seized the opportunity for synergy to provide the municipalities with an economical fibre-optic network. The 50 km long trenches produced for the power lines in 2017 were used to co-locate an ND 92/80 mm protective sleeve, which provides the foundation – the "backbone" – of the fibre-optic network in the Engadine between Bever, Zernez and Pradella. EE Energia Engiadina independently built an additional 25 km long line to provide the supply out of the valley from Pradella to Martina.

Over a total distance of 75 km in the backbone and 40 km in the feeder and in the drop (last section of the route to the house), several duct bundles (3x16x2.0, 3x14x2.0, 5x14x2.0) and individual ducts were drawn into the protective sleeve. In the subsection between the Ftan starting point and the Gurlaina endpoint in the municipality of Scuol (Lower Engadine), the RAUSPEED 3x16x2.0 duct bundle, a 32x2.3 PE pipe, and a shield wire were drawn into the previously installed protective sleeve.

The good blowing-in result is not due merely to the experience of EE Energia Engiadina, the blowing device and the cable. The technical features of the microduct also play a decisive role in blowing-in success. The REHAU trapezoidal grooving, proven and patented for decades, promises particularly good blow-in results with low cable wear. Thanks to the large minimum internal diameter of the RAUSPEED pipes, as well as the moulded parts (permanent connectors), which are adapted to the tight tolerances, the best conditions for blowing-in are guaranteed. The pipes are not stringently inspected at the factory for no reason: every metre of pipe produced is tested for its blowing-in capability using ball, pressure and mandrel tests.

Thanks not only to the synergies associated with the co-installation of the protective sleeves, but also as a result of the long blowing distance, it was possible to save additional civil engineering costs. In addition to detached houses, commercial properties, hotels and other distribution points were also connected using fibre-optics and in future will enjoy a better connection at fair prices – together with a wonderful view.