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Voltage Drop

Inputs

Circuit category
A
m
mV/A/m

User-supplied — read this from your own copy of BS 7671 Appendix 4. This app never reproduces the licensed table.

Result

✓ PASS
5.840 V2.539 %

Limit (lighting) 3% · Table 4Ab

Utilisation 85%

T3 calculator — verify this result against your own calculation before relying on it professionally.

V_d = (mV/A/m × I_b × L) / 1000

V_d = (7.30 × 32.00 × 25.00) / 1000 = 5.840 V

  • Design current I_b: 32.00 A
  • Circuit length L: 25.00 m
  • Tabulated mV/A/m: 7.30 mV/A/m
  • Voltage drop V_d: 5.840 V
  • Voltage drop, % of nominal: 5.840 / 230 × 100 = 2.539 %

Clause: Appendix 4 §6.4 (Table 4Ab) · BS7671:2018+A4:2026

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