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Armoured Cable Current Capacity:
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The current carrying capacity of armoured cables refers to the maximum electric current that can be safely carried by the cable under specified conditions without exceeding its temperature rating. This is determined by factors such as cable size, insulation type, and installation method according to standards like BS 7671.
The calculator uses standardized table values from BS 7671:
Where:
Explanation: The values are derived from BS 7671 tables that account for thermal characteristics and installation conditions.
Details: Accurate current capacity calculation is crucial for electrical safety, preventing cable overheating, ensuring proper circuit protection, and complying with electrical regulations.
Tips: Select the appropriate cable size, insulation type (XLPE or PVC), and installation method (in air or buried). The calculator will provide the current carrying capacity based on BS 7671 standards.
Q1: What is the difference between XLPE and PVC insulation?
A: XLPE (Cross-linked polyethylene) has higher temperature resistance (90°C) compared to PVC (70°C), allowing higher current capacities for the same cable size.
Q2: Why does installation method affect current capacity?
A: Cables buried in ground have better heat dissipation than those in air, often resulting in slightly higher current capacities for the same cable size.
Q3: Are these values applicable for all voltages?
A: The current capacities are typically for low voltage applications (up to 1000V). Higher voltage applications may require derating factors.
Q4: What factors can reduce current carrying capacity?
A: Grouping of cables, high ambient temperatures, and installation in thermal insulation can significantly reduce current carrying capacity.
Q5: Should derating factors be applied?
A: Yes, the tabulated values are for reference conditions. Actual installation conditions may require application of appropriate derating factors.