Ballast units

Ballasts – Essential Components for Professional Event Lighting

Ballasts are indispensable components in professional event technology, ensuring the safe and efficient operation of discharge lamps, fluorescent tubes and certain LED systems. Whether you are lighting a concert stage, a trade fair stand or a theatre production, the right ballast guarantees stable current limiting, reliable ignition voltage and optimal lamp performance. LTT offers a comprehensive range of ballasts tailored to the demanding requirements of event professionals, lighting technicians and stage designers. From conventional magnetic ballasts (KVG) to high-efficiency electronic ballasts (EVG) and modern LED drivers, you will find the optimal solution for every application in our portfolio.

What Are Ballasts and Why Do You Need Them?

A ballast is a device connected in series with a discharge lamp to limit the current flowing through the lamp. Without a ballast, the ionisation process inside a gas-discharge lamp would cause the current to rise uncontrollably until the lamp is destroyed or the circuit breaker trips. The ballast performs two critical functions: it provides the high ignition voltage required to start the lamp (often several hundred volts up to several kilovolts, depending on lamp type), and it regulates the operating current to the lamp's rated value once the discharge has been established.

In professional event technology, ballasts are used with HMI lamps in moving heads, discharge lamps in followspots, fluorescent tubes in cyclorama lighting and certain LED modules that require constant-current drive. The ballast can be a separate component installed in the luminaire housing, or it can be integrated into the lamp base (as with compact fluorescent lamps). Modern electronic ballasts also incorporate pre-heating circuits for fluorescent lamp electrodes, eliminating the characteristic flicker associated with older starter-based systems and extending lamp life significantly.

Choosing the correct ballast type is essential for achieving the desired light output, energy efficiency and lamp longevity. Magnetic ballasts operate at mains frequency (50 or 60 Hz), while electronic ballasts convert mains voltage into high-frequency AC (typically 25–50 kHz), resulting in flicker-free operation and lower power losses. For LED-based stage lighting, dedicated LED drivers regulate either constant voltage or constant current, ensuring stable brightness and preventing thermal runaway.

Types of Ballasts: KVG, VVG and EVG Explained

Ballasts for professional lighting are available in three main categories, each with distinct characteristics and applications.

Conventional Ballasts (KVG)

Conventional magnetic ballasts consist of an iron-core inductor (choke) wound with copper or aluminium wire. They operate at mains frequency and are extremely robust, often functioning reliably for decades without maintenance. However, KVG suffer from relatively high power losses (10–20 per cent of lamp power) due to resistive losses in the winding and hysteresis and eddy-current losses in the core. A 58 W fluorescent tube with a KVG typically consumes around 71 W total system power. KVG also require a separate starter for fluorescent lamps, which causes the familiar flickering during lamp ignition. Due to their poor energy efficiency, KVG with energy class D have been banned from sale in the EU since May 2002, and class C devices since November 2005.

Low-Loss Ballasts (VVG)

Low-loss magnetic ballasts use improved core materials, larger copper cross-sections and optimised magnetic circuit design to reduce losses to approximately 14 per cent. A 58 W fluorescent tube with a VVG consumes around 66 W total. While more efficient than KVG, VVG still operate at mains frequency and require a starter. Since April 2017, only electronic ballasts with energy class A1 or A2 may be placed on the EU market, effectively phasing out VVG.

Electronic Ballasts (EVG)

Electronic ballasts represent the current state of the art. They rectify the mains voltage, then use a high-frequency inverter (typically 25–50 kHz) to drive the lamp. This approach offers numerous advantages: a 58 W fluorescent tube with an EVG consumes only around 55 W total (approximately 23 per cent energy saving compared to KVG), the lamp operates flicker-free, lamp life is extended by up to 50 per cent, and the ballast can be designed for dimming and remote control. EVG incorporate the starter function, so lamps ignite instantly without visible flicker. High-quality EVG achieve power factors of 0.97–0.99, minimising reactive power and harmonics. For professional event applications, dimmable EVG of energy class A1 BAT (Best Available Technology) are the preferred choice.

Ballasts for Stage and Event Lighting – Professional Requirements

In professional event technology, ballasts must meet stringent requirements that go beyond those of general commercial or residential lighting. Stage lighting often involves high-wattage discharge lamps (HMI 575 W, 1200 W, 2500 W and beyond), which demand ballasts capable of delivering precise ignition pulses and stable current regulation under varying mains conditions. Moving heads and automated fixtures require ballasts that can withstand frequent on-off cycling, mechanical vibration during transport and rapid temperature changes during outdoor events.

Compliance with DGUV Vorschrift 17 (formerly BGV C1) is mandatory for electrical equipment used in temporary event installations in Germany. Ballasts must be TÜV-certified and designed to prevent electrical hazards even under demanding conditions. For outdoor festivals and touring productions, ballasts with robust enclosures (IP-rated housings) protect against dust and moisture ingress. Redundancy is critical: professional lighting designers often specify backup ballasts for key fixtures to ensure the show can continue even if a component fails.

Brand compatibility is another important consideration. Professional manufacturers such as Showtec, Cameo, Eurolite and Futurelight design their luminaires around specific ballast characteristics. When replacing or upgrading ballasts, you must verify that the output wattage, voltage and current match the lamp specification. For example, an HMI 1200 W lamp requires a ballast capable of delivering the correct ignition voltage (typically several kilovolts) and maintaining the rated arc current (around 10 A at 120 V DC). Mismatched ballasts can lead to unstable arc discharge, reduced light output, colour temperature shifts and premature lamp failure.

LTT stocks ballasts from leading manufacturers including Osram, Philips and specialist event-technology brands, ensuring compatibility with the full range of professional stage lighting equipment. Our technical support team can advise on ballast selection for specific luminaire models and installation scenarios.

Electronic Ballasts (EVG) – Advantages for Professional Use

Electronic ballasts offer compelling advantages that make them the preferred choice for professional event lighting installations. The energy savings alone can be substantial: a typical 58 W fluorescent tube system consumes 71 W with a KVG but only 55 W with an EVG, reducing power consumption by 23 per cent. For large-scale installations with hundreds of luminaires, this translates into significant reductions in operating costs and carbon emissions. The lower heat dissipation also reduces cooling requirements in enclosed spaces such as television studios and conference centres.

Flicker-free operation is critical for video and film production. Conventional ballasts operating at 50 Hz mains frequency produce a 100 Hz light modulation that can cause visible banding or rolling bars when captured by cameras. EVG operating at 25–50 kHz produce light modulation at frequencies far above the critical flicker fusion threshold, ensuring smooth, flicker-free illumination even when recorded at high frame rates. This makes EVG indispensable for broadcast studios, concert live-streams and professional video production.

Dimmable EVG enable precise control of light levels, essential for creating dynamic lighting scenes and adapting to different performance requirements. Modern EVG accept control signals via DALI (Digital Addressable Lighting Interface), 0–10 V analogue or DMX512, integrating seamlessly with professional lighting control systems. Dimming curves can be programmed to match the creative intent, from smooth linear fades to logarithmic curves that better match human perception.

Lamp life extension is another key benefit. EVG with warm-start or programmed-start modes pre-heat the lamp electrodes before striking the arc, reducing thermal shock and electrode erosion. This can extend lamp life by 50 per cent or more compared to conventional starter-based systems. For touring productions and rental companies, the reduced lamp replacement frequency lowers maintenance costs and minimises the risk of lamp failure during critical performances.

High-quality EVG from manufacturers such as Osram, Philips and Tridonic incorporate active power-factor correction, ensuring a power factor close to unity and minimising harmonic distortion. This is particularly important in large installations where poor power quality can cause voltage drops, overheating of neutral conductors and interference with audio equipment.

LED Drivers vs Traditional Ballasts – Understanding the Difference

LED drivers are the modern equivalent of ballasts for LED-based lighting systems, but they operate on fundamentally different principles. While traditional ballasts limit current in gas-discharge lamps by providing inductive or electronic impedance, LED drivers regulate either constant current or constant voltage to power LED arrays. Understanding the distinction is essential when upgrading from conventional discharge lamps to LED technology.

Constant-Current LED Drivers

Most high-power LEDs used in professional stage lighting (such as those in LED moving heads, wash lights and PAR cans) require constant-current drive. The driver maintains a fixed current (typically 350 mA, 700 mA or 1050 mA) regardless of the forward voltage drop across the LED string. This ensures stable brightness and prevents thermal runaway, a condition where increasing LED temperature reduces forward voltage, which in turn increases current, further raising temperature in a destructive feedback loop. Constant-current drivers are specified by their output current and maximum output voltage (e.g. 700 mA, 40 V max).

Constant-Voltage LED Drivers

LED strips and certain modular LED systems operate from constant-voltage supplies, typically 12 V DC or 24 V DC. The driver regulates the output voltage while allowing the current to vary according to the load. Current-limiting resistors or integrated driver ICs on the LED module itself regulate the current through individual LEDs. Constant-voltage drivers are specified by their output voltage and maximum current (e.g. 24 V, 5 A).

Retrofitting LED Tubes

When replacing fluorescent tubes with LED tubes, compatibility with the existing ballast is critical. Some LED tubes (often labelled "retrofit" or "plug-and-play") are designed to work with existing EVG, while others require the ballast to be bypassed and the tube connected directly to mains voltage (these tubes have an integrated driver). A third category, "hybrid" tubes, can operate either with an EVG or with direct mains connection. Always verify the tube specification and follow the manufacturer's installation instructions to avoid damage or safety hazards.

LED drivers for professional applications must meet the same stringent requirements as traditional ballasts: high efficiency (modern drivers achieve 90–95 per cent), low electromagnetic interference (EMI), flicker-free output (especially for video applications) and compatibility with dimming protocols (DALI, DMX, 0–10 V). LTT offers a comprehensive range of LED drivers from leading manufacturers, ensuring you can specify the optimal solution for your LED lighting project.

LTT – Your Specialist for Event Technology

LTT has been your reliable partner for professional event technology for over 25 years. As both a specialist retailer and a manufacturer with our own production facilities in Germany, we offer not only a comprehensive product range but also in-depth technical expertise and first-class service. Our portfolio includes ballasts for all common lamp types, from compact fluorescent lamps to high-wattage HMI discharge lamps, as well as modern LED drivers for the latest generation of stage lighting.

When you order from LTT, you benefit from fast delivery from our warehouse in Bocholt, Germany, with free shipping on orders over €69 and express delivery options for urgent projects. Every product is backed by our 3-year warranty, giving you peace of mind for your investment. Our international shipping network ensures that customers worldwide can access high-quality event technology at competitive prices, and we offer wholesale terms for resellers and rental companies.

Whether you are equipping a permanent installation, planning a touring production or building up your rental inventory, LTT provides the professional-grade ballasts and drivers you need to set the stage for impressive results. Our experienced team is available to advise on product selection, compatibility and installation, ensuring you specify the optimal solution for your application.

Upgrading from KVG to EVG – A Practical Guide

Upgrading from conventional magnetic ballasts (KVG) to electronic ballasts (EVG) is a cost-effective way to improve energy efficiency, lighting quality and lamp life in existing installations. However, the conversion requires careful attention to compatibility and wiring to ensure safe and reliable operation.

Verify Lamp Compatibility

EVG are designed for specific lamp types and wattages. A ballast intended for T8 fluorescent tubes (26 mm diameter) will not work correctly with T5 tubes (16 mm diameter), and vice versa. Check the lamp type (T5, T8, T12), wattage (18 W, 36 W, 58 W, etc.) and length, and select an EVG explicitly rated for that lamp specification. Using an incorrectly rated EVG can result in reduced light output, flickering, shortened lamp life or complete failure to ignite.

Match Output Channels

EVG are available in single-lamp, dual-lamp and multi-lamp configurations. If your luminaire contains two 58 W lamps, you can either install two single-lamp EVG or one dual-lamp EVG. Dual-lamp ballasts are often more compact and cost-effective, but single-lamp ballasts offer redundancy (if one ballast fails, the other lamp continues to operate).

Bypass the Starter

EVG incorporate the starter function electronically, so the mechanical starter must be removed and replaced with a starter bridge (also called a starter dummy or bypass starter). This is a simple plug-in component that short-circuits the starter socket, allowing the EVG to control the lamp directly. Failure to install a starter bridge will prevent the lamp from igniting. Starter bridges are inexpensive and widely available; LTT stocks them for all common lamp types.

Rewire the Luminaire

The wiring configuration for EVG differs from that for KVG. Consult the EVG manufacturer's wiring diagram and follow it precisely. In most cases, the mains supply connects to the EVG input, and the EVG output connects directly to the lamp holders. Remove any capacitors previously used for power-factor correction, as EVG have integrated power-factor correction and external capacitors can cause malfunction. If you are not confident in electrical work, engage a qualified electrician to perform the conversion.

Test and Commission

After installation, switch on the luminaire and verify that the lamp ignites instantly without flicker. Check that the light output is stable and that no unusual noise or vibration is present. Modern EVG operate silently, so any audible hum or buzz indicates a problem (loose connections, incorrect wiring or a defective ballast). If dimming is required, ensure the EVG is a dimmable model and that the control signal (DALI, 0–10 V or phase-cut) is correctly connected.

Upgrading to EVG not only reduces energy consumption and operating costs but also improves lighting quality and reduces maintenance. For large-scale installations, the return on investment can be achieved within one to two years through energy savings alone.

FAQ – Questions & Answers