Norman Lamps, Inc.

Festoon bulbs are tubular miniature bulbs with electrical contacts on both ends, creating a compact cylindrical light source used extensively in automotive interior lighting, license plate lights, map lights, vanity mirror lights, trunk lights, and similar applications. The festoon configuration – sometimes called "torpedo" or "shuttle" bulbs – allows for simple installation by pressing the bulb between spring-loaded contacts that grip the metal caps on each end. This design is particularly common in European vehicles and has become increasingly standard in domestic vehicles as well.

The size designation indicates the length in millimeters. Common sizes include 31mm (approximately 1.2 inches), 36mm (1.4 inches), 39mm (1.5 inches), and 42mm (1.65 inches), with 36mm and 39mm being particularly prevalent in automotive applications. The exact size matters because festoon bulbs fit in specific mounting points with fixed spacing – a 31mm bulb won't make proper contact in a 39mm socket, and a 42mm bulb won't fit in a 36mm space. Checking the size of the bulb you're replacing or consulting vehicle documentation ensures getting the correct length.

Traditional incandescent festoon bulbs typically consume 5-10 watts depending on size and brightness requirements, producing warm white light at around 2700K. These bulbs have been automotive standards for decades, providing reliable illumination for interior applications. However, the heat generation and power consumption of incandescent festoon bulbs are considerations in vehicles where battery drain matters and where heat buildup in enclosed spaces (like map light housings) can be problematic. Lifespan for incandescent festoon bulbs typically runs 1,000-3,000 hours.

LED festoon bulbs have become extremely popular as replacements for incandescent versions, offering dramatic advantages in automotive applications. A typical LED festoon uses 0.5-2 watts versus 5-10 watts for incandescent, reducing electrical load on the vehicle substantially – important for vehicles with many interior lights or for applications like campers and RVs running on battery power. LED festoon bulbs run cool enough to touch even after extended operation, eliminating the heat concerns of incandescent bulbs. Lifespan of 25,000-50,000 hours means these bulbs can literally last the life of the vehicle with normal use.

The configuration of LEDs within festoon bulbs varies significantly across products. Basic LED festoon bulbs might have 3-6 LED chips producing adequate light for basic applications. High-output versions pack 12-24 LEDs or more to create very bright illumination suitable for map lights, trunk lights, or anywhere maximum brightness is desired. Some LED festoon bulbs use side-firing LEDs that direct light perpendicular to the bulb axis, improving light distribution in certain fixture types. Color temperature in LED festoon bulbs typically ranges from warm white (3000K) to cool white (6000K), with cool white being popular for its crisp, modern appearance.

One consideration with LED festoon bulbs in automotive applications is polarity – LEDs only work when connected with correct positive and negative orientation. Some vehicles have polarized festoon sockets ensuring bulbs can only be inserted one way. In vehicles with non-polarized sockets, you may need to try the LED bulb in both orientations to find which way works. Some premium LED festoon bulbs include polarity correction circuits that allow them to work regardless of orientation, though these typically cost more.

Marine applications also use festoon bulbs extensively for cabin lights, nav lights, and various interior illumination. The same size designations apply, though marine fixtures may have different mounting styles. LED festoon bulbs are particularly valuable in marine applications due to the reduced power draw (critical when running on battery), cool operation (no heat damage to fixtures or nearby materials), and long life (difficult to access locations need less frequent service). Ensure marine LED festoon bulbs are rated for the voltage of your marine electrical system – typically 12V but sometimes 24V on larger vessels.

Common Sizes: 28mm, 31mm, 36mm, 39mm, 41mm, 42mm, 44mm lengths. Width typically 10-12mm depending on bulb style.

Technologies: Traditional incandescent (5-10W, warm white), LED (0.5-2W, various color temperatures, 25,000+ hour life)

Typical Voltage: 12V (most automotive and marine), some 24V for commercial vehicles and larger marine vessels

Applications: Automotive interior lights (dome, map, vanity, license plate, trunk, courtesy), marine cabin lighting, RV interior lights, various miniature lighting applications