Confused about light bulbs?
We're here to enlighten you!
I had a great response to my plea for feedback and ideas for future Circuit Shorts topics. Thanks for all the great ideas I will definitely be using some of them and please keep them coming. This month's Circuit Shorts was the brilliant idea of Ali from Suffolk. Thanks for your great idea, Ali, your "I'm Steve's Star of the Month" badge is in the post. As you probably know, shopping for light bulbs can be a nightmare. You can leave the shop empty-handed and feeling as if you need a degree in electrical engineering. Believe me, the myriad of choice confuses me sometimes! Hopefully this month's Circuit Shorts will clear up some of the confusion and shed some light (see what I did there?) on the many possibilities.
- Bulb cap types -
The most important (and occasionally forgotten) item to check when choosing a light bulb is the fitting or cap required. With so many different light bulb fittings available it’s an easy mistake to make. Above are some of the most common cap types available in the UK.
The most popular fitting in the UK is the screw cap, available in several sizes but the most commonly used are:
E27, also known as Edison Screw (ES); and
E14, also know as Small Edison Screw (SES).
Another popular fitting is the bayonet cap, available in two sizes:
B22, also known as Bayonet Cap (BC); and
B15, also known as Small Bayonet Cap (SBC)
There are also specific caps like the GU10 for downlights or other special light fittings. These were traditionally available only as a halogen bulb but LED variants are now available, and finally low-voltage G4 and mains-powered G9 halogens. Please click here for a far more detailed information sheet listing all the available cap fittings.
- Different bulb types -
Halogen light bulbs
Halogen light bulbs are the perfect choice if you're looking for a more energy efficient bulb but still want to enjoy the same quality of clear, warm and sparkling light that you are used to. Designed to mimic bright sunlight, halogen light bulbs are filled with a mixture of argon and halogen gas and have a tungsten filament. They are also made from a higher-grade glass that can tolerate the extra-high temperatures they generate. They do cost more than standard light bulbs of the same wattage, but they're 20% more efficient and last up to 3 times longer. They come in 2 versions: a mains voltage (240 volt) and a low voltage (12 volt), with the latter requiring a transformer. However, the EU plan to ban all halogen bulbs as early as next year and replace them with more energy efficient models.
Pros
Cheapest to buy of the 'New Era' technologies
Familiar warm light
Dimmable
Same look and size as traditional incandescent bulbs
Full brightness instantly
Uses 2-25% less energy than incandescent bulbs
Contains no harmful chemicals
Cons
More expensive to run than other 'New Era' technologies
Still inefficient (only 20% energy saving vs incandescent)
Short lifetime (approx. 2,000 hours)
Energy Saving CFL (compact fluorescent light bulb)
CFLs need a little more energy when they are first turned on, but once the electricity starts moving, CFLs use about 70% less energy than incandescent bulbs because they convert more of the energy they use into light, instead of heat. They give off a bright white light ideal for kitchens, but are also available in cool or warm light versions for use in other rooms. If you use fluorescent bulbs, it’s important to remember that they contain mercury (in miniscule quantities), so they must be recycled rather than thrown in the bin. Also known as Compact Fluorescent Lamps (CFL), these are often referred to as 'energy saving' bulbs.
Pros
70% energy saving over incandescent equivalent
Low running costs
Dimmable
10 x longer lifetime than incandescent bulbs (approx. 10,000 hours)
Cons
Slightly harsher light than incandescent
Can take up to 2 minutes to reach 100% brightness
Most contain traces of mercury so require careful disposal
Bulbs tend to be larger than the incandescent bulbs so may not be suitable for all light fittings.
Incandescent/ traditional bulbs
Although, incandescent bulbs are still around today, their technology has been surpassed by new CFL, LED, and other lights but they still offer a very practical lighting solution for some commercial applications. The EU planned a progressive phase-out of incandescent bulbs due to the fact that they are not energy efficient. However, some manufacturers and retailers have found a loophole in the new rules and some incandescent light bulbs are still available, marketed as "rough service" or "shock resistant" bulbs for industrial use only. So, while incandescent lights might not be the most recent technology, they still have some key advantages that make them useful for commercial lighting in certain situations.
Pros
Work well for lighting small areas
Cheap to produce means they’re cheap for the consumer.
No toxic materials like mercury, making them safe to handle and to dispose of.
Cons
Not very energy efficient, only 10% of the energy used goes to creating light. The rest is lost to heat
Don’t work well in large areas
Lifespan has been surpassed by other lighting solutions
LED light bulbs
Without compromising quality, LED light bulbs offer unlimited lighting possibilities. They combine state-of-the-art technology with familiar design as they are available in the all the same shapes as classic bulbs
The most efficient bulbs available, using around 90% less energy than incandescent bulbs, LEDs (Light-Emitting Diodes) produce light through the use of semi-conductors. Unlike previous forms of energy saving bulbs, like CFL, they instantly reach full brightness and are available in dimmable versions.
Maintenance is also minimal - LED’s usually have an average life of anywhere from 35,000 to 200,000 hours. With average usage, LED's will last 15 to 20 years. Imagine not changing a lamp for over 15 years! Compare this to the measly 1,000 hours that an incandescent will burn. The upfront cost of purchasing LEDs is high compared with other less efficient lighting technology but they’ve usually paid for themselves within a few years thanks to energy savings. For more information on the benefits of LEDs, see our previous Circuit Shorts here
Pros
Ultra low running costs (90% energy saving)
From 35,000 to 200,00 hours lifespan
Full brightness instantly
No harmful materials
Familiar warm light
Dimmable options available
Cons
Not all equivalent wattages and shapes are available yet
Most expensive of the new technologies
Did you know? Although the LED itself runs at a low temperature, the electronic circuit inside the bulb will heat up. A heat sink is put in place to keep the LED as cool as possible; the bulb will still become hot to the touch but not nearly as hot as fluorescent, halogen or incandescent bulbs.
- Other information -
Dimmable bulbs
It is important to remember that dimmers require dimmable bulbs, so keep this in mind when you are choosing your bulb. In the past, older types of energy-saving bulb tended not to be dimmable; however these have now been replaced with a new generation of non-flicker models that are also dimmable. Halogen bulbs are generally easy to control with a dimmer switch, however, not all LED lighting is designed to be dimmable, and using a non-dimmable bulb with a dimmer switch can cause the bulb to not work properly or fail completely. So if you want to buy a dimmable bulb, make sure you check the product details to see if it will work with a dimmer. There are many benefits to using dimmable LED’s over dimmable halogen bulbs. As well as using up to 90% less energy, dimmable LED’s maintain their colour temperature and luminous efficacy unlike halogens which perform differently when dimmed.
When using dimmable LED bulbs an LED compatible dimmer switch will also be required. It may therefore be necessary to replace existing dimmer switches if it is currently used with halogen or incandescent bulbs.
There are two main types of dimmer switch:
Trailing Edge Dimmer Switches – Used with LED bulbs.
Leading Edge Dimmer Switches – Used with halogen and incandescent bulbs.
Note: Dimmable LED bulbs can also be used with a standard on/off light switch if you do not need to use them in a dimmable application.
Watts and lumens (brightness)
In the past, when nearly everyone filled their homes with incandescent bulbs, brightness was measured in watts - which is actually a measure of power. Since the introduction of energy-saving bulbs this is a less useful measure of brightness as new bulbs use a lot less power to produce the same amount of light. So, instead, light output is measured in lumens. The higher the number of lumens, the brighter the light.
Use this chart to see equivalent watt and lumen output for old-style incandescent and the three-types of energy-saving bulbs (LEDs, halogens and CFLs).
As a rough guide, around 400 lumens would be suitable for a bed-sized table lamp, whereas you might want between 1,500 and 3,000 lumens in total (from more than one bulb) for a good-sized living room.
This month's light bulb moment is actually about light bulbs! (You couldn't make this stuff up). As you all know, there are squillions of different bulbs out there and I might be stating the obvious, but why not take the old light bulb, or even the box it came in, with you? Even if you want to try something different, at least you will make sure you get the right cap fitting. Whenever I install new lamps for a client I always leave one of the light bulb boxes for reference. And if you have the old light bulb or box with you, the shop assistant may be able to guide you in the right direction without you having to draw them a diagram.
If you would like some advice on purchasing light bulbs or if you would like to make an appointment for a free quotation on any of the services we provide (click herefor more details about the electrical services we can provide for you) then please contact me.
Next month: Our guide to downlights
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Steve Bishop is a qualified electrician and a member of NAPIT. To see his qualifications click here.
