Power distribution unit with multiple CEE outlets for safely distributing mains voltage to various lighting fixtures on set.
Definition
The distro box is a mobile power distribution unit that splits the main power input of a film production into multiple fused outputs. Standard distro boxes convert 32A or 63A CEE connectors (380V/16A or 380V/32A) into 6-12 individual Schuko or CEE outlets. The term derives from the English "Distribution Box," which has been used in electrical engineering since the 1920s.
Technical Details
Professional film distro boxes operate with 400V three-phase power and feature individual 16A circuit breakers per output. Typical configurations are 32A input with 6x16A output or 63A input with 12x16A output. The internal structure consists of a main switch, RCD (Residual Current Device) safety switches (30mA), and individual circuit breakers. Housings are made of impact-resistant ABS plastic or die-cast aluminum with IP44 protection rating. Weights range between 15-35kg depending on the configuration.
Subtypes include single-phase distros (230V), three-phase distros (400V), and hybrid versions with mixed outputs. Special variants for LED technology operate with reduced amperage, while HMI distros offer reinforced 125A outputs.
History & Development
The first film distro boxes emerged in the 1950s in Hollywood studios as permanently installed panels. Mobile versions developed from 1965 with the advent of the New Hollywood movement and exterior shoots. German manufacturer Hauser Elektrotechnik presented the first European standard film distro with 32A inputs in 1978.
The integration of RCD safety switches began in 1985 following stricter safety regulations. Digital monitoring systems with load indicators became established from 2010, while modern smart distros have enabled remote monitoring via app since 2018.
Practical Use in Film
In "Blade Runner 2049" (2017), DoP Roger Deakins used 18 parallel distro boxes for the complex LED wall lighting in the replicant scenes. Standard workflows involve a main distro box at the generator, from which sub-distros lead to individual lighting groups.
Distro boxes reduce cable runs by an average of 40% and allow for selective switching of individual lights without needing to access the generator. Disadvantages include additional transport logistics and potential failure points with blown fuses.
Comparison & Alternatives
Distinguished from simple multi-way sockets by professional safety technology and higher current carrying capacity. Spider boxes serve as smaller, mobile alternatives with 4-6 outputs for location shoots.
Modern DMX-controlled distros are increasingly replacing manual versions as they allow remote switching of individual circuits. For LED-heavy equipment, more compact 16A distros are often sufficient instead of classic 32A versions.