How do I size a breaker for several LED high bays?

1. Why sizing by running current trips

Inrush is a current spike of milliseconds at switch-on, caused by charging the input capacitors of the driver, and it can reach several times the running current.

Ten luminaires on one circuit do not give ten times the steady-state current but a single combined spike, and that spike hits the instantaneous trip region of the breaker rather than its overload region.

That is why a fitting passes on the bench and trips on site, and the usual cause is the sizing basis rather than the luminaire.

2. Matching the trip curve

Under IEC 60898, a type B breaker trips instantaneously at roughly three to five times rated current, type C at five to ten times, and type D at ten to twenty times.

Multiply the per-driver inrush amplitude by the number of luminaires to get the combined peak, then check whether that peak falls inside the instantaneous band of the curve you selected.

If it does, there are three ways out: move to a flatter curve, split the circuit, or specify a driver with lower inrush.

3. What to get from the supplier

Ask for the inrush amplitude and duration of a single driver, both numbers, because amplitude alone will not let you add them up.

Xingguang supplies both figures at quotation stage and suggests a curve type for your circuit count, so it can be handed to your electrical designer for review.

Final selection still rests with local electrical codes and the site design.