Table of Contents
2. CONSTRUCTION WORKS
Underground Anchor
The underground anchoring structure is built into concrete foundation and is made of stainless steel. The preparation of the foundation depends on the structure of the ground on the designated location. The underground anchoring structure can be combined with reinforcing steel.
The self-standing charging station set contains an underground anchoring element which has a double function:
It supports the weight of the charging station.
It prevents tilting of the charging station.
Figure 4: Assembled underground anchoring element
The dimensions of the underground anchoring element are:
Width: 390 mm.
Length: 477 mm.
Basic depth without reinforcing steel and concrete base: 504 mm.
Construction of Underground Anchoring Element
The underground anchoring element is made of stainless steel and is built into concrete foundation. The preparation of the foundation (its dimensions) depends on the structure of the ground on the designated location.
The underground anchoring element can be combined with reinforcing steel. It is recommended to add construction steel into the L profile side holes to strengthen the anchor. Construction steel with diameter of up to FI 12 can be used. Please note that the upper part of the underground anchoring element has a rounded corner at its front left side.
It should therefore be installed so that this round corner is matched by the front left side of the charging station in final installation set-up.
The upper plate of the foundation has an opening for the insertion of supply cables. During installation, a pipe with an enough bending radius is placed into the foundation. The pipe is later used for the insertion and connection of supply cables.
The upper part of the foundation is equipped with a frame with the height of 60 mm. The frame enables concreting of the foundation to its final height and placement of finishing tiles or paving stones on the surface surrounding the charging station.
The underground anchor is optimised for shipping and needs to be assembled before construction by following the steps below:
Screw nuts on each anchor rod. There are six rods in the anchor package. Be careful to observe the nut positions on the rod as pictured below:
Figure 5: Anchor rod with initial screw positions
Place the rods into the anchor frame holes. Screw nuts on the other side at the top of the frame, where the rod enters through the frame. Tighten upper and lower nut firmly. Repeat for all 6 rods.
Figure 6: Insertion of anchor rods into the upper frame (bottom view)
Figure 7: Insertion of anchor rods into the upper frame (top view)
Place the L profile on the bottom of the anchor. Place all tree rods in one line into the L profile holes and screw nuts also on the bottom of the L profile, where the rod enters through the L profile. Tighten upper and lower nut firmly. Repeat for the second L profile and other three rods.
Figure 8: Insertion of anchor rods into the bottom L profile
During final mounting, the charging station is attached to the six protruding bolts of the underground anchoring element. The screws on each of the six bolts need to be removed first and are later used to fix the casing of the charging station to the foundation once it has been placed in the correct final position.
Excavation
The first step of the construction work is to prepare an excavation with the minimum basic dimensions of 550 mm x 420 cm and at least 600 mm in depth. If the charging station is combined with safety arches, a larger excavation is needed. If necessary, the dimensions of the foundation can be enlarged by adding reinforcing steel to the concrete foundation to enable construction of a larger foundation.
Figure 9: Basic excavation – longitudinal section
Figure 10: Basic excavation – transversal section
The two figures above show a longitudinal and transversal section of the basic excavation, together with the dimensions of the underground anchoring element which is concreted into the foundation. The basic excavation is suitable for installation of charging station without safety arches. One of the requirements of basic installation is to carefully observe that the height of the upper edge of foundation is precisely aligned with the height of surface finish in the area around the charging station.
Important: When inserting the anchoring structure be sure that the orientation is appropriate depending on how you want your charging station turned.
Construction of the Foundation
Important: When inserting the anchoring structure be sure that the orientation is appropriate depending on how you want your charging station turned.
Important: Make sure that the anchoring structure is inserted into the whole in horizontal position with the the part with holes oriented towards the sky.
The procedure for the construction of foundation and placement of the underground anchoring element into concrete is as follows:
According to the alignment of the power cable, the location of the installation pipe is determined. The pipe is placed into the foundation and used to connect the charging station to the network. It is recommended that the installation pipe ends over the foundation and not beneath the foundation. The bending radius of the power cables must be considered when placing the installation pipe. The dimension of the pipe depends on the number and diameter of power cables which will be inserted. In the case of clustering of charging stations in the same area, it must be considered that two power cables will be inserted into the installation pipe. The size of the opening at the top of foundation enables the installation of two installation pipes that are used when the clustering of charging stations is executed.
The concrete base is placed into the construction pit to the level that enables the top of the underground anchoring element to reach the desired final height. The final height in this case is the level of surface finish after completed works (for example the top level of paving stones, tiles, or curb). The concrete base is levelled so that the anchoring element can be vertically aligned. It is of utmost importance that the anchoring element is aligned very precisely. Lean concrete mix should be used for the concrete base (with less cement than water).
The installation pipe is inserted through the opening of the underground foundation anchor and attached with a wire to prevent it from slipping into the foundation during concrete works. The installation pipe, which has been cut to its final length, must be clogged on both ends with paper or similar material, so that the concrete cannot enter the pipe.
The concrete works can be started at this point. First the area around the installation pipe is concreted, where the pipe must remain accessible after the concrete works are finished.
Once the concrete reaches the level of the frame, the concrete works continue through the upper opening of the underground anchoring element, where the installation pipe is placed. The entire space inside the frame must be filled with concrete. In the case of low temperatures, the concrete must contain anti-icing additives.
The next step is precise levelling of the foundation and the concrete around the frame, where the finishing tiles will be placed. Precise levelling of the underground anchoring element is important for later installation of the charging station. After the construction of the foundation is finished, the charging station can be aligned only with the use of washers, placed on the bolts of the underground anchoring element.
The concrete must be left to dry for at least 48 hours (two days) before the cables are inserted into the foundation and the charging station is installed on the foundation.
Installation of Safety Arches
The charging station manufacturer supplies optional safety arches:
Safety arches prevent mechanical damage to the charging station which may result from collisions with vehicles.
The manufacturer normally supplies a set of safety arches (1 or 2 pieces), which are installed either at both sides of the charging station (2 arches) or in front of the charging station (1 arch).
If safety arches are added to the charging station, the foundation needs to be prepared in advance, to add the safety arches to the same foundation as for the underground anchor.
Excavation and Foundation Construction for Safety Arches
If safety arches are added to the charging station, the foundation needs to be enlarged accordingly (as presented on the following figures). Safety arches are placed in the same foundation together with the charging station.
There are several guidelines that need to be observed when installing safety arches:
The safety arches protect the front side of the charging station; therefore, the arch must be aligned with the rear side of the station (underground anchoring structure).
The safety arches on the left and right side of the charging station must be placed at a distance at least 15 cm from the station.
The height of the installed arches is 70 cm above the final level of the foundation.
If the charging station is located on the pavement, the two front ends of the safety arches must be installed at the edge of the roadside curb and the charging station must be placed away from the roadside curb so that its rear end is aligned with the two rear ends of the safety arches.
The station can be protected by one or two safety arches that can be placed at both sides of the station (2 arches) or only at the front (1 arch).
Figure 11: Longitudinal section of the excavation with two safety arches
Figure 12: Longitudinal section of the excavation with one safety arch
The figures above show a longitudinal section of the excavation in all cases where the charging station is combined with safety arches. The arches must be removed at least 15 cm from the sides of the charging station to enable normal opening of station's maintenance doors.
The height of the concrete base must reach such a level that the height of the safety arches will be exactly 70 cm above the surface finish. Safety arches need to be precisely levelled during the concrete works to prevent any later tilting.
Figure 13: Transversal section of the excavation and safety arches on the curb with two safety arches
The figures show a transversal section of the excavation when the charging station is placed on the pavement and combined with safety arches. The safety arches need to be placed as close to the roadside curb as possible. The underground anchoring element is moved back accordingly, so that the rear side of the charging station (anchoring element) is aligned with the front side of the rear arches of the safety arches.
Figure 14: Transversal section of the excavation and safety arches on the curb with one safety arch