How Light Works: The Ultimate Guide

When you’re starting to choose lighting for your home, it can be tough to know where to begin, even if you’re certain of the style you’re looking to create in your home. With so many different lighting options available, and lots of variables between the different types of bulbs, it can be pretty mind blowing. Through this post, we’ll take you through the different categories of lighting that you need in a room, and the types of fixtures that you can use for each category. From there, we’ll cover the important issue of light bulbs, since they’re pretty complex, and understanding how they work makes buying them much simpler.

We’ve written this post with absolute beginners to lighting in mind – those who are setting out living on their own for the first time, new home owners, and those who have previously ‘made do’ but are now ready to create a stylish home that they can be proud of.

 

How light works a beginners guide light bulb sketch

 

What different types of lighting are there?

Where once we would have relied solely on the ceiling light to provide all the light in a room, today designers and lighting experts recommend having a range of different lighting available in a room – with at least one from each lighting category, to allow for optimal amounts of light for all the types of activities that may take place in the room. The main categories are ambient lighting, task lighting, and accent lighting.

As an example, in a bedroom:

  • Ambient lighting allows for getting dressed and moving around
  • Task lighting would allow for reading or for applying makeup
  • Accent lighting may be used to illuminate wall accessories, behind a TV or an aspect of the room’s design

 

Ambient lighting

Ambient light completely fills the room with light, and allows you to use the room as if it is daytime. It is often provided by the ceiling light in the centre of the room, but there are other types of lighting that can contribute to ambient indoor lighting.

It may be the case that producing the optimal amount of lighting requires a number of lights to be used at the same time.

 

Task lighting

Task lighting does exactly what it sounds like – it produces light for specific purposes. This could be for reading, cooking or for studying. Task lighting can be provided by a range of lights, including:

The type of task lighting that may be required is likely to differ from room to room and between the type of activity that it is needed for. For example, a desk lamp that is only used with a PC, or under-counter lights in the kitchen may be able to be a fixed type, whereas for craft activities, a lamp with a moveable head may be desirable.

 

Accent lighting

Accent lighting can take many forms, but is primarily there to highlight an accessory such as artwork or an architectural feature. This can be provided by lots of different types of lights:

Since accent lighting is there to highlight, then simpler light fixtures can help to keep the focus on the feature.

 

scene accent highlight lighting example in an art gallery

 

What type of lighting fixtures should I use?

The decision about which lighting fixtures you prefer is a personal one, and should be based on the type of look you are aiming to achieve in the room – but having at least one (if not more) of each type of lighting means that you’ll have the flexibility, and will be able to create the brightness that you need at any given time.

 

Ceiling lighting

Ceiling lighting is often the first lights that get chosen when moving into a new home. They tend to provide the general illumination in a room, but also add to the styling of the room.

While your personal preference, and the style and visual weight will ultimately guide your choice of ceiling lighting fixture, there are approximate calculations that you can use to narrow down the type of fixture that will work best in the space.

Working with the dimensions of your room in feet (rather than centimetres), add the number of feet in the width to the number in the length. The answer will give you the number of inches that your light fitting diameter should be. For example, if your room is 6 foot by 10 foot, the optimal size of light fitting would be 16 inches – which is about 40cm.

If you’re choosing statement lighting such as pendants that hang from the ceiling, the first thing to do is to get your tape measure out. It should go without saying, but you will need sufficient clearance underneath the fixture to avoid breakage and potential injuries. When hanging feature lighting from the ceiling, it is essential to have a minimum of two metres clearance between the floor and the bottom of the fixture (and if some members of the household are particularly tall, maybe a little more). If you’re hanging pendant lighting above dining tables, there should be at least 65cm between the table and the lighting fixture.

 

Wall lights

Wall lights can be used for all kinds of purposes – either to add to ambient lighting, as task lighting or as accent lighting – as well as providing a decorative accessory in a room with simpler styling. The function of the wall lights will influence the type of fixtures that you choose, while the style of the room will influence the type of wall lights that are chosen.

Where wall lights are used for effect, there may be a number of wall lights used – either paired, or in a series – or they may be positioned in an unusual spot. Using wall lights with colourful shades, and matching them with ceiling lighting can help to tie the overall look and feel of the room together, particularly where other accessories in the room coordinate.

 

Lamps

Whether you are choosing floor lamps, table lamps or desk lamps, as with wall lights, you’ll make your decision based on the size of the room, what category of lighting it is providing, and what activity the lamp will be illuminating.

Depending on their size, table lamps may contribute to the ambient light in a room, or may be purely used as task lighting – for example, for reading, or as a portable lamp that can be used for sewing or other types of crafts. Since more of us are using electronic devices for reading today (and are attached to our phones too), many styles of lamp now include USB charging points as part of their design. Where lamps are used for reading, dimmer switches are desirable – since this allows for better lighting throughout the day and night, when different levels of lighting are appropriate.

When choosing a table lamp:

  • Be sure that the bottom of lamp shade is approximately at eye level when seated, so that the bulb doesn’t shine directly in your eyes
  • Situate the lamp close enough to illuminate the task sufficiently
  • If the room has people walking through it often, then ensure your lamp is stable, so to prevent it tipping over
  • Ensure that the relative proportion of the lamp is appropriate – it should be no more than one and a half times the height of the item furniture that it sits on

When choosing a floor lamp:

  • As with table lamps, ensure that the lower edge of the shade is at eye level when seated
  • Avoid obstructing the view of décor such as artwork, as well as between seating locations
  • The smaller the room, the smaller the lamp should be
  • Keep safety first – if the floor lamp is likely to become a trip hazard (especially for children or elderly residents) it isn’t the right one

 

table desk floor lamp lighting

 

What type of light bulb do I need?

Once you’ve established the type of light fittings that you’re going to use in a room, and you’ve decided on the exact ones that you’re going to buy, you’ll need to choose your light bulb. Not all light fittings will have bulbs sent with them, and where they are, the bulb may not be to your preference. Choosing a light bulb isn’t always easy or straightforward either – since there are a number of variables that you’ll need to consider.

 

Choosing the right light bulb

If you’re replacing a bulb in an existing light fixture, the rule is to replace like with like – especially when it comes to the type of fitting. But the fitting isn’t the only thing you’ll need to consider. You’ll need to think about what the light is for (is it for ambient, accent or task lighting?), and what shape suits the fixture, as well as the cost both of the purchase, and in the longer term. Let’s take a look in more detail.

 

Fitting

While there are plenty of different types of light bulb fitting, when we’re looking at domestic light fittings, there are three main types that prevail: bayonet, screw cap, and pin and push-fit base bulbs. Generally, with these types of light fixtures, it should be easy to find a bulb that will suit.

When changing a bulb, you’ll need to find the same type of fitting for the replacement. Although adaptors are available, they should rarely be required, since different types of bulbs are so easily found today, especially from lighting specialists.

But establishing the fitting of the bulb is the easy part, since you don’t have to opt for the same colour or brightness – which is what we’ll come to next.

 

Function

As we’ve already determined, there are many different types of lighting fixtures, that can be used for different purposes. The function that the light fitting fulfils will determine the brightness, and the hue of the bulb that you choose.

 

Brightness

Newer types of bulbs use different amounts of watts to produce the same amount of brightness – and there are differences between types. Historically, light bulb manufacturers used the number of watts that were required to produce the amount of light to illustrate the brightness of a bulb.

Today, bulbs are much more efficient, and to produce the same amount of light as an old style incandescent 60 watt bulb, an LED bulb needs just 10 watts, while a halogen bulb requires around 42 watts. The differences in watts required for the same amount of light is the reason that light bulb manufacturers no longer use the measurement of watts to describe the brightness of a light bulb. So rather than measure the amount of power required, manufacturers now use Lumens to describe the levels of brightness that the bulb will provide. The higher the number, the brighter the light provided by the bulb.

 

Warmth

When choosing your light bulbs, you’ll also need to consider whether you want a cool toned, or a warm toned bulb. The decision will depend on several factors:

  • What type of fixture you’re using the bulb in
  • The space the light is being used in
  • What activities the light will illuminate
  • The time of day the room, and the light will be used

For rooms that require lighting levels that are near daylight, and that aren’t being used close to bedtime, then a cooler toned bulb can be used – bright white, or slightly blue-toned, will help to mimic natural daylight. Where being alert is not as desirable, such as for bedside table lamps, then warmer, yellow toned bulbs are preferable.

The measurement of bulb warmth is measured in Kelvins. The warmth of candle light is measured at approximately 1,500 Kelvin, while normal daylight (depending on whether it is a sunny or cloudy day) is measured at between 5,000 and 7,000 Kelvin. The higher the number on the Kelvin scale, the colder the light provided will appear, and cooler toned bulbs often appear to be brighter than warmer toned bulbs of the same Lumen measurement.

 

kelvin colour temperature scale infographic

 

Choosing the bulb

Although watts are no longer used as a measurement of light bulb brightness, most bulb manufacturers will display both the Lumen measurement, and the equivalent in watts in an older style incandescent bulb, as well as the Kelvin measurement on the packaging. Not only that, but there will also usually be a description in words to describe the type of light – such as ‘warm white’. That means that when you’re in a store picking a light bulb, if you’re used to choosing bulbs based on watts, you’ll be able to see the numbers that you need, and the description will help if you’re not sure.

 

Format

Once you’ve decided on the colour, brightness and you know the fitting that you need, you can narrow down the shape that you want. There are an incredible array of different shaped bulbs, from traditional ‘bulb’ shapes, to candle, golf ball, pear shape, spiral and stick bulbs – and once you’ve established that you have the correct cap fitting (either screw or bayonet, for example) and the correct brightness, it is up to you. In many cases, if the bulb is hidden, the choice of bulb will be simply down to personal preference and it won’t matter. However, if your lighting fixture intentionally exposes the light bulb, then it may be better choose a style with a decorative filament, or that complements the design of the fixture.

 

Cost

While the general rule of buying the best quality you can afford definitely comes into play here – since a better quality bulb is likely to last longer too. The longer-term cost of running a bulb will also be relevant, especially if you are in your ‘forever home’. The initial cost of LED bulbs are higher than other types, but they are much more energy efficient, and can last for up to 25 years. Not only does this provide much more convenience – you won’t need to replace it as often – but the energy savings can add up dramatically. Savings can add up to more than £180 over the product’s lifetime, which makes it well worth the investment.  ­

 

Final thoughts

We’ve covered the basics of lighting in this post, and yet we’ve barely touched on design. Understanding the basics of lighting is important though, and can help to guide your decisions when you’re designing, and shopping for the room of your dreams. Our key takeaways:

  • Ensure you have a range of lighting in each room, with at least one light from each category of ambient, task and accent lighting
  • Be careful to measure before making a purchase – having lighting that is in proportion to the room, and that allows sufficient clearance is essential
  • Choosing the best bulb for the purpose should be done carefully, with the correct brightness and colour taken into consideration

Our range of lighting covers all the types of fixtures mentioned in this post, and we stock an extensive range of bulbs. If you are looking for a particular item, or need technical advice, please get in touch – our team of experts are happy to help.

 

charles author bio

Charles Barnett Managing Director

Charles started Lyco in 1995 with just 4 enthusiastic employees and has grown it considerably over the past 25 years. Charles is also the Managing Director of Lighting Direct and newly acquired Online Lighting. He now has a team of 50 lighting experts working on growing Lyco Group to be the UK leader in lighting for both businesses and homes. Away from the office he is a keen cyclist and is proud to have cycled 1017 miles from Lands End to John O’Groats to raise money for a new residential centre for adults with multiple learning difficulties.

Light Fittings Types – Traditional Light Bulbs

When we think of a light bulb, we used to refer to an incandescent or tungsten filament lamp with a round sphere at one end or a candle lamp that is long and thin. Nowadays we talk more about LEDs, since LED bulbs are more energy efficient, cheaper to run and better for the environment. Most light bulbs have round metal caps with either a screw or bayonet type fitting

At Lyco, we sell a wide range of traditional light bulbs as well as more specialist types, and we understand that knowing which type you need is not as simple as it once was. With this in mind, we have put together a quick guide to fitting types, and traditional light bulbs.

 

traditional light bulb gls

 

Standard Fittings & Effects

The types of lamp available with screw and bayonet caps have broadened greatly in recent years, and now include LED bulbs. With traditional cap fixtures, you get great flexibility and a wide choice of lighting effects.

 

Domestic Bulbs

In the UK, bayonet and screw caps are the most commonly used type of light bulb. When it comes to which type is better, there isn’t a huge amount of benefit in opting for one or the other – the only exception is that bayonets are less likely to work loose from their fixture unintentionally, and there are no threads to be accidentally stripped or removed.

 

Bayonet Bulbs

There are two different types of bayonet cap – standard and small. Standard bayonet is by far the most popular and is perhaps the most common light bulb of all in the UK.

The bayonet cap type fitting (BC) is perhaps the most well-known lamp fitting in the UK today. Invented towards the end of the nineteenth century and utilising a mechanism originally developed for bayonet rifles, the BC consists of a spring and two contacts with bayonet mounts on either side.

To fit a bayonet light bulb, simply depress the lamp into its holder, twist under the lugs and the bayonet mounts are retained by the springs, thus ensuring optimum contact. It is a simple push and twist motion that most of us are familiar with.

 

Size Variations

The most common sizes of bayonet cap fittings are BC or B22d, (where 22 refers to the diameter, in mm of the lamp base) and small bayonet cap – SBC (or B15d). For insulation and safety purposes, these types of fitting typically feature a plastic or metal skirt.

 

Common Uses

It is most common to find bayonet fittings in pendant lights, batten holders, wall and ceiling lights designed for domestic use. BC fittings can be enclosed in some very decorative luminaires and traditionally incandescent tungsten filament lamps are used. Nowadays, there are also low energy lamps with bayonet caps, which mean you can keep your existing fittings and reduce damage to the environment at the same time.

 

GU10 bulbs

This type of bulb has a twist and lock mechanism, and so tend to be classified as a type of bayonet bulb. G means that the bulb has a bi-pin, or double pin base, and the pins are 10mm apart, and protrude 7mm from the base of the bulb. GU10 bulbs tend to be found in spotlights, kitchens and bathrooms, directional downlights and recessed lighting.

 

Screw Cap Bulbs

Screw caps are available in four common sizes – Micro (MES), Small (SES), Standard (ES) and Goliath or Giant (GES).

Another very popular fitting type for domestic lighting purposes is the screw cap – invented by Thomas Edison in 1909 and trademarked under Mazda.

Using the metal screw as one contact and a single base as the other, the lamp simply screws into the fitting. Contact is made when the lamp screw is almost home, thus making the screw part both the physical and electrical contact that makes the circuit.

 

Screw Cap Reliability

The screw fitting is considered by some as easier to maintain, particularly as there are no springs involved which can fail over time. However, there is a small drawback in that it is possible to cross-thread, which can be a problem when the bulb needs to be replaced, or there may not be a secure flow of electricity.

 

Size Variations

The most common type of screw cap in the UK is the ES or Edison Screw E27, (where the number relates to the diameter of the screw). This size of screw cap bulb tends to be the one that is found in standard light fixtures in homes.

There are other, smaller sized screw light bulbs, such as SES or Small Edison Screw (E14), Giant or Goliath Edison Screw GES (E40) and MES or Miniature or Micro Edison Screw (E10). These tend to be used in decorative lighting where the bulb is exposed, and so needs to be smaller for aesthetic reasons.

To find your ideal bulb by shape or cap try our Light Bulb Finder

Although the Edison Screw is the most popular choice for domestic fittings, there are now many more Small Edison Screw lamps available. This is because retailers are sourcing light fittings from Europe and the US, where this type of fitting is far more common.

Giant Edison Screw fittings are generally not suitable for domestic use and more suited to specialist street lamps and industrial fittings. MES fittings are less common and ideal for use in very small or battery powered light fittings.

 

Pin & Push-Fit Base Bulbs

This type of bulb is fitted in the exact way that it sounds like it does – it gets pushed into the fixture, without needing to be screwed or twisted. The base on this type of bulb will have a number of pins, usually two, of a variety of lengths and types of pin. Incandescent, halogen or fluorescent lamps tend to have bi-pin fittings.

Pin and push-fit bulbs don’t have integrated control gear, which means that they need a ballast, transformer, or driver in order to regulate the bulb.

 

Halogen Bulbs

Halogen spotlights tend to have push-fit pin bases, and are often shaped in order to stop the wrong type of bulb being used in a fitting.

 

Fluorescent tubes

Fluorescent tubes tend to have two pins at either end of the tube, as do LED strip lights. Standard size T8 (25mm), and T12 (38mm) fluorescent tubes use the G13 fitting, while smaller fluorescent tubes like the T5 (16mm) use the G5 fitting.

 

Strip Lights

Strip lights are a form of incandescent lighting with unique double-ended sprung fittings. They are commonly used for picture lights, and this type usually has a 15mm diameter S15 fitting, while others have two S14 connectors at either end of the lamp. Other applications have tended to be superseded by linear fluorescent tubes as they are more reliable.

 

Wedge Base Bulbs

Wedge base bulbs can be thought of as similar to bi-pin bases, but rather than pins, they have wires that go from the inside of the bulb into the fixture. Care needs to be taken with this type of bulb, as it requires force to be inserted and removed. Their most common use is in Christmas tree lights and fairy lights, and today due to the fact they are so inexpensive to manufacture, customers tend to replace the whole set of lights rather than single bulbs.

 

light bulb types and fittings gls gla LED

 

Other Light Bulbs

In addition to the common bulb fitting types there are many other less common types available, typically for more specialist use. Whatever type of bulb you are replacing, it is important to remember that you should always replace like with like.

 

Heater & Catering Bulbs

Catering light bulbs come in variety of types, from doubled ended (strip light / linear halogen fittings) to Edison screw and bayonet fittings.

 

PAR Lamps

PAR (parabolic aluminized reflector) lamps are frequently used where directional beams are required and are common in many different types of setting. They tend to be of the sealed beam variety, with a curved mirror (the parabolic reflector) behind one or more filaments. With LED PAR bulbs, there is often a different type of optical system, or there may be individual LED reflectors.

Some PAR lamps have a screw terminal for better electrical contact, while others have a GX160 2 pin cap with ceramic base. The fittings are usually porcelain to take the high heat output. Retrofit equipment is sometimes available where LED bulbs are required to be used in place of PAR bulbs.

 

Professional Light Fittings

For high intensity luminaries (for film, stage, and TV use for example), professional fittings such as the T and A types are most commonly used. Caps are two pin, being either GY9.5 or P28S.

 

How To Choose The Best Light Bulb For Your Needs

Now we’ve gone through some need to know information about light bulbs, let’s talk about how to choose the best type for your needs. You might still be confused – and that’s OK, there are a lot of things to think about! Fitting, function, and format are the three things to consider, as well as finance – so let’s take a look.

 

Make Sure You Know The Type Of Fitting You Need

Most of us will have been there at some point – you get to the shops, with ‘light bulb for [room]’ on your list, and you realise that you have forgotten to check which type of fixture you need. The best way to ensure you get the right one is to take the old one with you – but sometimes that isn’t possible.

If it isn’t practical to take the old bulb to the shop with you, then take a couple of photos of the fittings, and any numbers printed on the bulb on your phone before you set out. Trust us – you’ll thank us when you’re stood in front of what seems like hundreds of different types of bulbs!

If you end up in that situation though, don’t get stressed – you can head home and order the exact bulb you need from us, with delivery direct to your door.

 

Know What The Function Of The Bulb Is

Light bulbs are just to produce light – right? Of course that is the primary thing, but there is a whole lot more to consider when choosing the best bulb. Aside from knowing whether the light is for functional, ambient or accent lighting, the brightness and the colour of the light being produced is really important when choosing a bulb for your home, since you’ll need the right type for different spaces.

 

Brightness

In the past, we used to simply buy bulbs according to how much power they used. That meant that the higher the wattage, the brighter the bulb would be. With newer light bulbs, manufacturers no longer use watts to measure the brightness. That’s because it isn’t as accurate to measure the power according to the brightness – watts measure power, and modern bulbs use far less power than they used to, while providing the same amount of brightness. (That’s also the case for car bulbs!)

Today, bulb brightness is measured in Lumens, and the higher the number of Lumens, the brighter the light. Typically, a reading lamp on a bedside table will be around 400 Lumens, but lighting from a ceiling fixture might be from 1500 Lumens – which you’d get from more than one bulb.

 

Colour

The colour of the bulb that you want will depend on the fixture you’re installing it in, and the function of that light. Bright, or cool white light mimics natural daylight, which will help to increase alertness, while warmer yellow tones can aid with feelings of relaxation and cosiness. That means you’ll want bright white bulbs in spaces where you need to be alert – ideal in home offices – and definitely not in the bedroom, because bright white bulbs will keep you awake.

Bulb manufacturers use the Kelvin scale to measure the colour temperature on light bulbs. The warmth of candle light is around 1,500 Kelvin, with normal daylight somewhere between 5,000 and 7,000 Kelvin. The higher the Kelvin measure, the cooler the light temperature – and a cooler tone can seem brighter than a warmer tone.

If you’re looking for a bulb that gives off about the same colour as an old incandescent bulb, then you’ll want a bulb at approximately 2,700 Kelvin.

 

kelvin colour rendering for light bulbs

 

How Does Colour Rendering Affect Light?

Colour rendering is a way of measuring how well a light accurately shows different colours. For the most part, that won’t be too much of an issue, but if you’re displaying a piece of art with accent lighting or photographing items that you don’t want to have to correct the colour on, then you’ll want a bulb that has a measurement on the Colour Rendering Index of as near to 100 as possible.

 

Decide What Shape Is Best

While as long as you buy a bulb with the correct fixture, it will work, getting the correct shape of the bulb is important aesthetically. The type of shade you’re putting your bulb into will strongly influence the shape of the bulb that you need, especially if the shade or lighting fixture intentionally exposes the bulb for effect, or if you want to avoid it being seen, then you’ll need a smaller bulb.

 

Know The Long-Term Costs

While quality LED bulbs seem like they’re an investment when you buy them, but they really are the most energy efficient type of bulb available at the moment. When you consider that LED bulbs can last up to 25 years, that investment is well worth making, even just for the convenience of not having to change the bulb alone! When you compare the performance of an LED bulb with the cost of a traditional bulb, you’ll save more than £180 in energy through the product’s life span, so it is well worth the investment.

 

Final Thoughts

We hope that this post has helped you to understand light bulbs a bit more clearly, but if you’re still feeling confused about different types of light bulbs, don’t worry – you are not alone! With so many different types, and decisions to be made, it is not surprising that so many people still find it tricky to get the right bulb. Remembering to think about fitting, function, and format is a good place to start – but if you’re replacing an existing bulb, try to replace like with like. Should you have a bulb that you’re absolutely stuck with how to replace, then you can call us on 0345 646 1133, or email the technical team on technical@lyco.co.uk.

If you are looking for traditional bulbs, why not take a look at our extensive range of incandescent light bulbs? Alternatively, our full range of light bulbs includes energy saving and LED options to suit all your needs.

 

Looking for more news, inspiration, or advice? Try our Lighting Advice section.

 

charles author bio

Charles Barnett Managing Director

Charles started Lyco in 1995 with just 4 enthusiastic employees and has grown it considerably over the past 25 years. Charles is also the Managing Director of Lighting Direct and newly acquired Online Lighting. He now has a team of 50 lighting experts working on growing Lyco Group to be the UK leader in lighting for both businesses and homes. Away from the office he is a keen cyclist and is proud to have cycled 1017 miles from Lands End to John O’Groats to raise money for a new residential centre for adults with multiple learning difficulties.