In response to the environmental characteristics of rural Africa, such as high temperature, high dust, rodent infestation, and easy wear and tear during overhead laying, the insulation layer thickness of the wires in the lighting electrical ready board must strictly comply with international standards such as IEC 60227 (PVC insulated cables with rated voltage of 450/750V and below) or IEC 60502.
Although the specific number of millimeters varies with the cross-sectional area of the wire (thickness of the copper core), in typical applications of rural lighting electrical ready boards, the nominal thickness of the insulation layer should not be less than 0.6 millimeters to 0.8 millimeters.
The TN-C-S grounding system is commonly used in rural power grids in Africa, and the voltage inside lighting electrical ready boards is mostly 230/400V. Based on the experience of rural electrification projects in countries such as Tanzania, copper core cables that comply with IEC 61089 or IEC 60227 standards are commonly used.
BV wire (polyvinyl chloride insulated hard wire): used for fixing wiring inside the box. For lighting wires of 2.5mm ² or 4mm ², the standard requirement for insulation layer thickness is usually 0.7mm-0.8mm.
Sheathed cable: If there is a risk of vibration or movement in the incoming and outgoing lines, a soft cable with a sheath should be selected, and the total sheath thickness is usually above 1.0mm.
In rural areas of Africa, the climate is dry and dusty, and lighting electrical ready boards are often hung on mud walls. The wires are prone to friction with the edges of the box due to thermal expansion and contraction. Even if the insulation layer of a single wire reaches 0.8mm, it is recommended to take the following measures:
Add protective layer: Use rubber gaskets at the inlet and outlet, or add nylon hoses or corrugated pipes to the wires to form a second layer of mechanical protection, preventing the insulation layer from being cut by the metal box.
Refusing to recycle cables: Although the insulation layer of inferior cables is thick, they contain many impurities and are prone to aging and cracking. UV resistant and aging resistant polyvinyl chloride or cross-linked polyethylene insulation materials should be selected to adapt to the strong sun exposure and temperature differences in Africa.
The standard thickness of the insulation layer is the basis for preventing leakage, but the construction process is equally critical:
Stripping specification: When stripping the insulation layer, the wire core should not be damaged, and the stripping length should match the wiring terminal to avoid exposing the copper core.
Environmental isolation: Considering the humidity during the rainy season and the potential risk of floods, the lighting electrical Ready Board Box should be installed at a dry high place with waterproof performance. If the local grounding system is incomplete and there is a risk of wire breakage, the voltage inside the box may rise abnormally. At this time, it is necessary to rely on a sturdy and voltage resistant insulation layer to ensure personal safety.