Why Are the Plastic Lugs on My Compact Fluorescent Lamp in a Different Position?

When replacing CFL lamps you may have noticed that the lugs (pins) are in a different position to your bulb, some people think they are either faulty or incompatible but infact the difference is intentional.  The wattage of the CFL determines the position of the lugs ensuring that there is no accidental installation of the incorrect bulb.

Why the lugs differ by wattage

CFL lamps come in a variety of wattages such as 10, 13, 18, 24, 26, 36, 40 and 55 Watts and have either 2 pin or 4 pins.  Manufacturers position these lugs differently depending on the wattage of the lamps and this serves multiple purposes.

1. Preventing incorrect installation
2. Ensuring proper electrical contact
3. Compliance with safety standards

What is the life of a compact fluorescent lamp?

CFL’s have a long lifespan compared to incandescent and halogen bulbs. A standard CFL has an average lifespan of around 8000 to 10000 hours but several factors can affect the CFL’s life.

1.  Frequent switching on and off - reduces the lifespan
2.  Enclosed fixtures - poor ventilation causes heat to build up and shortens the life of the lamp
3. Voltage fluctuations - Unstable electrical supply can damage the internal electronics

What happens if you put LED bulbs in a fluorescent fixture?

CFL lighting technology is being phased out and people are now considering replacing them with LED’s which use less energy, do not produce so much heat and last even longer, however just replacing CFL’s with LED’s is not straightforward,

CFL/Fluroscent are designed for use with a ballast and most LED’s do not require one,  If you install a LED in a CFL/Fluorescent without changing the wiring several issues can occur.

1.  The LED may fail to turn on as the ballast prevents proper voltage supply
2. The LED may flicker due to incompatibility
3. Prolonged use can damage the led driver inside the bulb and shorten the lifespan

Therefore it is very important to check whether your LED replacement is compatible with a ballast or whether you need to change the wiring.

Do I  need to remove the ballast to use a LED bulb?

In the majority of cases yes you would need to either bypass or remove the ballast.  This then ensures -

1.  The LED receives the correct voltage and operates smoothly
2. Maximum energy efficiency is achieved
3. The lifespan of the LED is preserved and you will have no flickering or overheating

Some LED bulbs are specific ballast compatible which allows you to replace the bulb without removing the ballast, however it is important that you check the compatibility with your fitting before installing.

Practical advice for replacing CFL’s

If your new CFL has the lugs in a different position to the original bulb it is most likely because it is designed for a different wattage than the previous one.  Always check the wattage on the original and ensure that it matches your fittings specifications. Installing a bulb with the correct wattage ensures you have the correct light output and the bulb lasts alot longer.

When considering LED replacements

1. Check whether the LED tube is ballast compatible
2. If not you may need to bypass or remove the ballast
3. Make sure the LED matches the fixture type and dimensions

If you adhere to these requirements you can replace CFL’s with LED’s safely and efficiently.

Conclusion

The lugs on CFL’s are positioned according to the wattage of  the lamp which is done to prevent incorrect installations.  CFL’s tend to have an average life span of around 8000 to 10000 hours.  When upgrading to LED versions it is important to consider the ballast requirements as installing LED’s without checking properly can lead to flickering, lamps not working or damage to the fitting.  Once you understand these requirements you can safely upgrade your lighting whilst maximising the efficiency and lifespan of the bulb.