Pluggable electrical installation in prefab concrete construction, concrete poured on-site and tunnel formwork

Tekst: Lieke van zuilenkom I Beeld: Isolectra

Van der Valk Hotel Gorinchem proves that it is possible! 

Pluggable electrical installation is becoming increasingly popular. In the meantime, the plug-and-play fitting concept and method has become indispensable in utility construction, where suspended ceilings, cavity walls, raised floors and cable ducts are often used. In short: it can be applied wherever there is sufficient space to install pluggable junction boxes, switchgear and cables. “Following in the footsteps of utility construction, pluggable electrical installation is also becoming increasingly common in residential development”, notes Casper Bontenbal, Marketing Manager at Isolectra. “This includes timber frame houses and houses with suspended ceilings, where electrical installations can be fitted smartly, quickly and flexibly. Thanks to Isolectra, these benefits are now also available for construction methods without ‘empty spaces’, such as precast concrete construction, concrete poured on site and tunnel formwork."

In terms of the development of pluggable electrical installation in wet concrete, it all started with a question received from Techval. “Skilled workers are becoming increasingly scarce and valuable”, says Robbert van de Laar, Project Manager at Techval. “We can make major gains with a method that allows for quicker and easier installation. Also in tunnel formwork. Normally, we first install a pipe and then draw the wires. With pluggable installation in concrete, we are done in a single step. Moreover, we no longer need fire barriers.” Colleague and Head Fitter Marcel Eijkemans: “In the circulation spaces, a higher fire class is required, which is based on different and more expensive cables. However, if you encase everything in concrete, this is efficiently covered. The fire class issue is then immediately resolved.”

Extensive testing and certification process 

In tunnel formwork, extreme conditions are the order of the day, as Bontenbal knows. “For example, electrical equipment is installed on the rebar, which people walk on, on which the concrete is poured and where the air bubbles are removed from the concrete using a vibrating device. Would the Wieland RST20® system also be suitable for this?" Wieland RST20® is IP69 certified, he says. This means that you can spray this system with water pressure up to 100 Bar. You can actually temporarily submerge the system. “Together with Wieland, we explored the possibilities of this system. We then started an extensive testing and certification process for the plugs. We poured them into concrete and carried out an extensive durability test under very tough conditions. Together with our sister company TKF, we have also developed a cable for concrete casting. This, too, was quite a journey, but it has resulted in a certified system for pluggable electrical installation in concrete.”

Van der Valk Hotel Gorinchem 

“In the summer of 2020, we invited Techval project leaders Bert Damen, Remco Nederkoorn and Robbert van de Laar to our head office to present all developments”, says Bontenbal. “As the conversation progressed, they became more and more enthusiastic. They even came up with a project where the system could be used: the new Van der Valk Hotel Gorinchem.” Eijkemans: “In this tunnel project, we are dealing with one type of room and many repetitive electrical installations. Pluggable installation in concrete is ideally suited for this project type.” Van de Laar: “The Van der Valk family is also very open to innovations and has given us permission to test various methods of building and connecting the electrical systems, in close consultation with the concrete builder, rebar worker and other parties on site.” 

Four methodes 

The construction of the Van der Valk hotel was due to start in September 2020. Due to the short lead time, it was decided that only floors 9 to 12 would be wired, says Cor-Hein Slobbe, Senior Product Manager at Isolectra, who was regularly on site to explain the various methods and answer questions from electrical contracters. “On all floors, cable boxes have been installed in the walls, including a connection option (switch, socket or lighting point) and a coiled wire or plug. From these junction boxes, one cable always runs upwards. In addition, a cable bundle has been put in the side walls, which can be linked in various ways. On one floor, for example, we already installed the junction boxes, while on another floor we tested a different type of junction box with more connection options and cables. On a third floor, the cables have already been fitted with plugs. Both at the junction box and at the wall boxes, allowing for easy installation with interconnecting cables. On the last floor, standardpluggable RST20® splitter blocks were also used, which made it possible to reduce the number of junction boxes in the ceiling.”  

Seamless integration 

To ensure seamless integration of the various methods, Slobbe visited the construction site at an early stage. To see, for instance, how the Techval team handled construction and installation. What would be the best methodology to support this electrically? Where could the cable bundles best be placed? And what were the storage facilities on each floor? “Together with the electrical installers on site and the Isolectra team, I discussed all possible solutions. Then, together with the assembly company and in consultation with the fitters, all the cables were made and coded.” Bontenbal: “In addition to the plug system and corresponding cables, in this project we have to deal with junction boxes to which the socket outlets or lighting points are to be connected. In order to ensure proper (watertight) connection of all cables, we have developed adapters especially for this project.” 

Combination with ‘dry’ systems  

In the Van der Valk Hotel, a central distribution board has been installed on each floor. “A power cable runs from here to all the rooms”, says Bontenbal. “The connections are pluggable. In the rooms, some of the installations run from the suspended ceiling to the bed wall panel and from the ceiling to the bathroom. The cables lead to a plug in a junction box, from which the rest of the hotel room is connected using a Wieland GST18® system.” Meanwhile, Techval is busy installing these ‘dry’ systems.

Evaluation 

All methods and findings were recently discussed in a follow-up meeting. “The evaluation showed, for example, that the use of the right type of junction box is very important”, says Slobbe. “But also that the cabling in the walls ideally protrudes just above the tunnels and is already fitted with a plug. This avoids conflicts and risks when the decking is placed on the walls. Moreover, people on the construction site are not hindered by large cable clutter piles. Once the ceiling network is complete, the cables are easily connected to the junction boxes in the ceiling using standard coupling cables.” A final learning point that those involved would like to share is that the preparation phase is essential – even more so than with dry construction methods. After all, no further changes can be made to the concrete.

In week 30, Van der Valk Hotel Gorinchem must be completed. Techval is currently rolling out pluggable electrical installation in concrete in two other major projects: the InLeisure hotel in Bloemendaal and the Van der Valk hotel in The Hague-Wassenaar.