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Cable Derating / Correction Factors
BS 7671 Appendix 4 combined correction factors and required tabulated cable capacity
The Ensign ToolboxCable Derating / Correction FactorsBS 7671 Appendix 4 combined correction factors and required tabulated cable capacity
Currents
A
The load the circuit must carry
A
Next standard device size ≥ Ib
A
From BS 7671 Appendix 4, before correction
Correction factors
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Table 4B1 — 1.0 at 30 °C; >1 below 30 °C
—
Table 4C1 — 1.0 single circuit; e.g. 0.80 for 2 bunched
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Reg 523.9 — 0.5 fully enclosed, 0.89 one side, 1.0 none
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0.725 for a BS 3036 fuse, 1.0 otherwise
Enter Ib, In and the tabulated It to calculate