Connecting a power cable directly to a live distribution panel without interrupting supply — a risky procedure reserved for emergencies only.
Technical Details
Standard hot patches are connected via CEE connectors: 16A (blue), 32A (red), 63A (red), and 125A (red) at 400V/50Hz. The cabling uses NYY-J cables with cross-sections from 2.5 mm² (16A) to 50 mm² (125A). Modern systems integrate RCD protection switches (30 mA) and circuit breakers according to the fuse rating. Mobile hot patch distribution units feature digital power meters and phase monitoring. For 125A connections, grounding resistances below 10 Ohms are mandatory.
History & Development
Hot patching became established from the 1970s onwards, parallel to the development of high-power HMI lights. Osram's first 12kW HMI lamps (1968) required stable mains supply instead of fluctuating generator power. The introduction of electronic ballasts (EVG) from 1985 onwards reinforced this development, as flicker effects increased with unstable power supply. Since the 2000s, digital load management systems have enabled simultaneous control of multiple hot patches with automatic phase distribution.
Practical Use in Film
Studio productions like "Blade Runner 2049" (2017) utilized 125A hot patches for 18kW HMI arrays at Alcon Studios Budapest. Location shoots often use 63A connections for 12kW HMI setups, for example, in interior shots in office buildings. LED panels from 1000W benefit from stable color temperature with constant mains voltage. Disadvantages: dependence on local grid infrastructure, limited mobility, and potential failure risks during grid disturbances.
Comparison & Alternatives
Generators offer independence but produce vibrations and exhaust fumes. 20kVA units provide comparable power to a 63A hot patch but require 200 liters of diesel per shooting day. Battery systems like Freefly Wave (960Wh) replace hot patching for LED setups under 500W. Hybrid systems combine hot patching with buffer batteries for uninterrupted power supply. For exterior shoots without a mains connection, generators remain the only option, while studio situations favor hot patching.