LED Light Bulbs

The most important specification for LEDs is the light output in lumens (lm). In the past, brightness was often estimated based on wattage. This does not work reliably with LEDs because their efficiency varies greatly.

Rule of thumb for comparison (for guidance only):

• approx. 400–500 lm ≈ old 40-watt incandescent bulbs
• approx. 800–1,000 lm ≈ old 60-watt incandescent light bulbs
• approx. 1,500 lm ≈ old 100-watt incandescent light bulbs

The higher the light output, the brighter the lamp appears, regardless of the power in watts.

For an LED light bulb to be a suitable replacement, the socket must be correct. Common base types include E27, E14, GU10, GU5.3 and G9. Tubes often use G13 or other variants.

The shape is also important: some lamps are compact, meaning that a large light bulb will not fit. With reflectors and spotlights, the shape also determines how the light is distributed.

The colour temperature is given in Kelvin:

• Warm white (approx. 2,700–3,000 K): warm, cosy light, ideal for bedrooms and living rooms
• Neutral white light (approx. 3,500–4,000 K): functional, clear, good for kitchens, bathrooms and hallways
• Daylight white (from approx. 5,000 K): very bright, rather cool white effect, ideal for workshops, commercial premises or concentrated work

The beam angle determines whether an LED spreads widely or works more like a spotlight:

• Narrow angle: targeted beams of light for spot and accent lighting
• Wide angle: even illumination of surfaces and rooms

Not every LED light bulb is dimmable. If a dimmer is available, the lamp must be explicitly marked as dimmable. In addition, many older dimmers are designed for halogen bulbs and can cause problems with LEDs (e.g. flickering).

LED light bulbs are usually easy to recognise:

• The packaging states the lumen (lm) rating, colour temperature in Kelvin, and often also whether the light bulb is Dimmable or the beam angle.
• The wattage is significantly lower than that of incandescent or halogen light bulbs in relation to brightness.
• ‘LED’ is clearly indicated, as are the base type and socket.

There are more reasons why LED light bulbs may flicker. It is often due to the interaction between the LED technology and the existing electrical system. Typical cases:

• The dimmer is not suitable for LEDs or is operating outside the optimal range.
• The LED is not dimmable, but is being operated in dimmed mode.
• Fluctuating voltage or inferior electronic components.
• For tubes: incorrect driver or unsuitable conversion.

The following usually help: a suitable LED dimmer, a high-quality light bulb or a compatible model for the existing driver.

In many modern LED lamps, the LED is permanently installed (‘integrated’). There are technical reasons for this: The LEDs are directly matched to the heat sink, driver and optics to improve efficiency, service life and design. This allows lamps to be built flat, more compact and more energy-efficient.

The disadvantage: if the LED or driver is defective, a simple replacement, as is often the case with classic base light bulbs, is often not possible or not worthwhile. As a rule, the entire lamp must be replaced.