The voltage drop of a board’s feeder and circuits, laid out like the usual calculation sheet.
Standards and regulations
BS 5467
Armoured cables with thermosetting (XLPE) insulation, 600/1000 V
The cable figures (mV/A/m) come from Ducab’s catalogue of XLPE cables made to it.
Formulas
Voltage drop of one cable
Vd = (mV/A/m) × I × L / (runs × 1000)
mV/A/m = the cable’s figure from the catalogue (size, cores, type)
I = the current (A): Revit’s load current, the load in kW, or the breaker rating
L = the length (m)
runs = cables in parallel
Drop from the origin
Vd% (total) = Σ Vd (origin → circuit) / U × 100
U = the circuit’s voltage
Checked against the limit: 3.5 % by default (14 V on 400 V), editable
Design rules it applies
The results are saved as Voltage Drop Parameters a panel schedule can show
Export to CSV
For reference. MO.tool works these out to help your design; the engineer remains responsible for it. Always check the edition of each standard your project uses and the requirements of the local authority (DEWA, ADDC, Civil Defence…).
