Inrush Current

The surge of current a fixture swallows at switch-on, before it settles into steady state — the time it takes the capacitors in its switching power supply to charge from zero. That peak typically reaches 5 to 10× steady-state, over 1 to 20 ms. Against it, a Type B MCB trips at 3 to 5× rated current (over >100 ms), a Type C at 5 to 10×. Hence the value of staggering the power-on sequence to avoid simultaneous inrush.