In the installation of a DC circuit, the sequence of tasks holds immense significance. Ideally, all DC wiring should be completed prior to the installation of a PV array.
This approach enables effective electrical isolation of the DC system using the DC switch-disconnector and PV module cable connectors during the array installation. Similarly, it facilitates electrical isolation of the PV array when the inverter is being installed.
Typically, the installation sequence would involve:
• Placing the DC switch-disconnector and DC junction box(es)
• Connecting the positive and negative cables of the string/array – extending from the DC disconnect/junction box to both ends of the PV string/array
• Running the main cables of the PV array from the DC switch to the inverter.
The process must ensure that installers are never required to work in an enclosure or situation where both live PV string positive and negative components are accessible simultaneously.
During subsequent module installation, the installer will handle live cables. However, since the circuit is broken at the DC switch-disconnector, the possibility of an electric shock current flowing from the partially completed PV string is eliminated. The maximum electric shock voltage that could be encountered is that of an individual PV module.
In cases where pre-installing a DC isolator is not feasible , cable ends should be temporarily placed in an isolation box and appropriately labeled.
Proper cable support is essential, particularly for cables exposed to wind. Cables must follow prescribed routes or be enclosed in mechanical protection. They should be well-supported and cable-tied (using UV-stabilized ties), and precautions should be taken to shield them from sharp edges.
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