Outdoor cable preparation using underground chambers

1. Introduction

Preparing the cabling allows charging infrastructure to be built in stages. Prepare the routes and connection points in advance, then add stations according to the number of vehicles and charging demand.

Underground chambers provide accessible points for cable entry and looping. They help extend the car park without repeating the entire cable route.

Below you will find the arrangement and procedure for the illustrated project example. The same principle can be designed for residential and company car parks.

 

2. Technical description

Our cabling preparation solution includes several key components that make charging station installation straightforward and quick:

• Cabling used — we create loops starting at the charging station distribution board. The loops are protected by a conventional 100 A circuit breaker, and one loop can serve several parking spaces or charging stations (typically 18 parking spaces). The exact cable types, protection and routing must be discussed with the designer. Here we describe a typical example of a larger car park, which may not be suitable in every situation. We run three cables underground in each loop: power, data and lightning protection. All three cables cover the needs of the entire charging station loop. For loops with more parking spaces, an ideal total is divisible by both 3 and 2, because many EVs are single-phase and can then be distributed evenly across a three-phase supply, and it is preferable to create an underground chamber shared by two parking spaces.   
  • Power cabling — to prepare for AC charging stations or DC stations up to 60 kW, we use AYKY or NAYY aluminium cables with cross-sections up to 50 mm². 
  • Data cabling — alongside the power supply cable, we install one data cable in the loop, ideally an outdoor cat5e cable.
  • Earthing — installation of a 30 × 3.5 mm FeZn earthing strip
• Chamber in the illustrated example: PVC pipe with an outside diameter of 400 mm and an inside diameter of 380 mm. Prepare the height and cable openings according to the installation drawing.

• Cover used — a plastic or cast-iron cover selected for the required load capacity. It can be integrated into interlocking paving and rated to support passing vehicles.

• Steel structure — a frame installed in the pipe to which the charging station is ultimately attached. A concrete foundation or other complicated mounting work is therefore unnecessary. The steel frame is secured level inside the pipe even if the pipe itself is not level. Holes are drilled in the cover for cables and bolts, allowing the charging station to be attached directly to the frame secured inside the pipe.

The installation procedure and complete video tutorial are available at THIS LINK.