400 V three-phase section
230 V single-phase section

Vd calculated for the three-phase mains,
cannot be added to the Vd calculated for the
single-phase circuits

Convert the single phase voltage drop values
to three phase by multiplying by 1.732. (square
root of 3). Then add together the three phase
figures and work on the three-phase Vd
allowance, which for 400 V works out to 20 V.

Convert the three-phase voltage drop values
to single-phase by dividing by 1.732. (√3).
Then add together the single-phase figures
and work on the single-phase Vd allowance,
which for 230 V works out to 11.5 V.

Convert the single-phase voltage drop values
to a percentage of 230 V and the three- phase
voltage drop values to a percentage of 400 V
and add the two percentages to check if 5 % is
not exceeded.