Maximum number of luminaires per electrical conductor

The maximum permissible number of luminaires to be connected to one conductor is generally limited by the permissible current load of the conductor. The luminaires’ power factor must be considered as well. Where it is unknown, λ ≥ 0, 9 can be assumed based on EN 60598 if "purpose-designed luminaires" or luminaires with a power consumption ≥ 25W are used (see also chapter 2.1.8.4 "Power factor"). With inductive luminaires intended for fluorescent lamps, on-site compensation measures must be considered as applicable (see chapter 2.1.10.6 "Reactive power compensation").

With

 

 

n

being the permissible number of luminaires

Imax

being the maximum permissible current

λ

being the luminaire's power factor

Psys,luminaire 

being the luminaire’s power consumption

The maximum permissible operating current is determined by the cable cross-section and the installation type (see above), but can be further limited by the voltage drop in case of extended cable lengths.