Prepping 1 Lighting Overview

Many people forget the significance of lighting and always assume it is there and always will be there and just take it for granted until it is gone and there are many types of lighting and each have pros and cons and the objective is to get the light you want or need which works for you in your desired, or required circumstances and getting this balance is crucial in many situations.

What is a light and how does it work? Basically it consists of a light source and this light source is left as is, or bounced off a reflector to give it a direction and shape and the reflector dictates both of these and finally there is the lens which works with the reflector by being matched to the reflector to give a light pattern which is a combination of light shape and spread.

All lights need power and traditionally this is from a recognised source such as mains voltage which can range from 100-240 volts AC or from a transformer or transformed source such as the industry standard 25 50 or 110 volts AC or DC sources of power such as batteries and while batteries can power lighting they tend to be fairly standard voltages or derivatives of voltages such as 1.5 volts. This is because most dry batteries are 1.5 volts and for a 3 volt bulb you use two dry batteries in series to give you 3 volts or 4 batteries in series to give you 6 volts. Voltage versus current is critical as every electrical item can be measured in watts which is volts X amps to give your wattage and many things can influence this as current or amps dictate how long something runs as simply amps (current) does the work and while the voltage may fall so does the amps and your battery goes flat.
Wet cells are usually filled with plates and a wet electrolyte such as lead or calcium plates with acid or acid paste and a lead acid cell is 2 volts and early car batteries were 6 volts or 3 X 2 volt wet cells in series in a single housing, 12 volts are fairly standard for cars and are 6 X 2 volt cells in series in a common housing and lorries and commercial vehicles are 24 volts or 2 X 12 volt batteries in series.
Newer button cells as used in car alarm fobs or remote control fobs are for low current draw for short bursts and generally come as 1.5 or 3 volts and lithium batteries are generally 3.7 volts rising to around 4.2 volts when fully charged and other rechargeable batteries are NiCad or nickel cadmium or Li-On or lithium ion and are generally 1.2 volts per cell.

Power sources are critical and to understand this we have to understand the relationship between voltage and current (amps) as this can significantly alter things, if you have a fixed wattage such as 12 volts X 1 amp you get 12 X 1 = 12 watts so how much life does this give your light? If you double the voltage you can halve your current (amps) to get the same 12 watts. 24 volts X 0.5 amps = 12 watts or halve your voltage and double your amps such as 6 volts X 2 amps = 12 watts.
This is needed when dealing with any lighting and particularly battery lighting as the amps dictate the light life and within reason you need as much amperage as you can get so you can increase the working life of your light, or increase the voltage of mains power to reduce your electricity bill which is measured in Kw or kilowatts as the input voltage is stable at 240 volts in the UK, and can be other voltages in other countries.

Light sources can vary and they all generally have specific uses and if we go back to World War II we can see some very powerful lights in action:

Arc lights work by generating an electrical arc between two electrodes and this is exactly the same as arc welding where you create an electrical arc to melt metal fillers into two metals; and by making the lights larger you could make the reflectors larger and fire this focused light thousands of yards (metres) in a beam into the sky and illuminate aircraft. Arc lights always had a generator with them as they required high voltages and massive currents to strike the arc initially, then lower voltages at high currents to maintain that light. This has a very narrow beam and a very focused light which gives us the focal length which is dictated by the light, width of light, and the distance combined to give the focal length. Therefore it may give a light intensity of 100,000 lumens of light in a 2 yard wide beam at 2000 yards and this is its focal length.
Arc lighting is better used for non cost efficient lighting such as the military who can fund the huge generators running costs, the huge costs of purchasing the lights and the constant maintenance costs of replacing and adjusting the carbon arc rods which generate the arc and this is on top of the immense heat they generate and their need for in service, efficient cooling.

Incandescent lighting is probable the best known as the traditional light bulbs for decades which worked by putting a tungsten wire across the two terminals of power and it heated up the wire until it glowed and in its day it was the traditional go to bulb for most applications as it could be used with AC or DC applications and as long as I was enclosed in a confined space it worked. Housings made of glass could be made in a range of sizes and styles and the traditional round bulb also had the flatter and slimmer pear bulb and the even smaller candle bulbs and even specialised bulbs such as the bulb in your fridge you took for granted.
This moved on from glass enclosures filled with air to glass housings filled with different gases which made the bulb filament burn hotter and a hotter burning filament changed colour from a yellow glow to a much bluer glow which to the naked human eye made the light appear whiter and brighter than it was. Despite making the filament burn brighter and whiter, the halogen gas actually served to cool the filament and stabilise its working temperature to stop it over heating and burning itself out.
Many of these bulbs came with fairly standard bulbs of the same shape but in different sizes and the introduction if gas filled bulbs with brighter lights deemed it necessary for traditional bulbs to catch up and they did this by matching a bulb to a reflector and the two were matched to a glass lens and the bulb itself had a shaped base so it would only fit one way into the light so everything matched.

Automotive lighting was potentially the first mass production lighting people will remember and these matched bulbs, lenses, and reflectors were also the ones people remember as the plain bulbs changed to gas filled bulbs so who remembers the H3 or H4 halogen bulbs of older vehicles. One advancement was the use of a directional bulb which changed its light output by having two filaments and one was the normal beam for normal driving and a second filament on a different plane to the first filament for full or high beam where it lifted and concentrated the light further in front of the vehicle for improved lighting range.

Lighting focused in one direction is called directional lighting while light designed to shine in all directions is called omnidirectional and this is the information we all need to know as a directional light from a torch shines where you point the torch and direct the light and omnidirectional light simply shines all around and lights something such as a room and the brightness of the light is measured in lumens. The more lumens you have in a specific space, the more light you have, but if the space is large and you have too few lumens you will not sufficiently light the room/space.

Discharge lighting is a fairly recent development in the lighting arena and this generally works by applying an electrical current to a starter which applies a high starting voltage to a gas filled tube and as it ignites and warms the gas, it glows and emits a light and once “struck” the voltage and current reduce in response to the light intensity which made them more energy efficient then incandescent or halogen bulbs. These types of lighting are not designed to be continually switched on and off as you would in the home so were more often confined to stores or factories and workshops where they were fitted in the ceilings at height meaning they were called “High Bay” lights where they were switched on in the morning and run all day before being switched off, or simply left on for weeks or even months. These are an omnidirectional bulb with a reflector fitted behind the bulb to reflect the light emitted at the rear of the bulb to the ground and not waste it.
Variations of discharge lights include the older orange and newer yellowy street lights as well as fluorescent tubes and while they vary slightly they are all struck or ignited gas lights except for fluorescent tubes which are usually a powder coating on the inside of the glass tube which when struck, turns from a powder into a gas. HID or high intensity discharge lighting used on motor vehicles is basically a discharge light with a shaped bulb to make a halogen type light a discharge light. Discharge lighting has the advantage if running a lot cooler then incandescent and arc lighting and the gas in a shaped bulb means a typical 55 watt headlight bulb in a standard or halogen type can be replaced by a typical 35 watt HID bulb, thus saving around 1.5 amps per bulb.
Power consumption is much lower as an arc light has to heat the electrodes to create the arc and incandescent lighting has to heat the filament hot enough to glow at white or orange/yellow heat and maintain it which draws power. Metal halide, mercury vapour and high pressure sodium are all forms of discharge lamps all primarily called “high bay” lights mounted above 18’ high.

LED lighting works differently as an LED is an electronic semiconductor and unlike the other mentioned lighting is something called polarity sensitive and this simply means it MUST be the correct polarity so you must identify the anode (positive) pin and the cathode (negative) pin and not connect them the wrong way round and they must be fed with exactly the correct voltage or have a resistor of the correct rating, or an LED driver placed into the circuit. Single LED’s or light emitting diodes are actually a diode which is essentially an electrical one way valve which serves to let electricity flow in one direction but not the other, an LED merely produces light as it does so. Most commonly the 5mm dome top LED is easily the most commonly used and a single LED is described by its size and style or body shape and then its colour so a 5mm dome top LED would be a round bodied LED with a domed top and this would be followed by its colour. Some colours such as white and blue cannot be produced as a light colour by a single LED so they achieve these colours by mixing colours as you would paint and to achieve white you actually mix red and yellow light and unlike paint mixed lights give different colours.

LED’s work by using a semi conductor and when you pass a current through it photons are produced at a specific light frequency and light at different frequencies are defined by the human eyes as different colours and the human eye cannot actually see some frequencies and these are generally called infra red frequencies and used as illuminators or night lights on CCTV cameras for example. These semiconductors are sat on a reflector and the amount of photons dictate the light brightness and the reflector dictates the light angle as it is emitted. Generally, single LED’s come from 3mm diameter to 10mm diameter with something called the viewing angle which is the angle the light is emitted and while a wide angle light may emit light of 10,000 lumens they may emit it at different angles such as a wide angle of 140° giving it a wide angle of light, or 10° meaning it will be a very narrow angle, but will illuminate much further.

LED’s have got smaller and more powerful meaning a smaller modern LED will produce more light from a smaller LED than it would 10 years ago and if you have a specific application or requirement you can mix and match the same LED with different viewing angles to give both wide angles for a wide spread of light with narrow angles of light which illuminate at distance. If you combine these smaller and single LED’s together you form a “package” which are a large number of tiny LED’s on a common base and these are called a “chip” as they are a single unit with either a fixed input voltage or a variable voltage between two specific voltages and an example would be a chip with input voltages of 10-14 volts.
When you package multiple LED’s onto a single base and form a chip and mix a number of LED’s with different viewing angles you have created something called an SMD or surface mounted device more technically known as a discrete or surface mount discrete and you can sell these as a single unit as a single LED light source for people to make their own lights or you can take a number and form then together on a tape known as a strip. These LED’s are merely formed in blocks where an input voltage is applied and a tiny LED driver is mounted in the tape and drives a small number of LED chips and each group is supplied power from common power rails embedded in the tape so all the blocks of LED’s are connected in parallel and each block is wired in series and each block has a cutting point so you can cut that block off and wire it straight to its power supply and it will work.
On things such as LED strip the LED’s are often defined by a number and a light output and the main LED numbers used for lighting are 5050 and 2835 and each pair of numbers states the LED size in millimetres and divisions of millimetres, therefore the 5050 can be broken into 50 x 50 meaning each LED chip is 5.0 or 5mm wide so the 5050 is 5mm X 5mm and the 2835 is 2.8mm X 3.5mm so let’s look at the numbers.

As an example I will use strip I regularly use and this is from a company called Lepro who can be found online and I usually buy my strip in lengths of 5 metres and here is our first number, the length of 5M and next is the input voltage of 12 volts and next is the number of 300 LED’s which is the total number of LED’s on the 5M length which is 300 LED’s or 60 LED’s per metre and a cutting point of every 3 LED’s which is where it can be cut and used. Next is the brightness of 2300 lm or 2300 lumens or 460 lumens per metre and a power consumption of 16 watts or 3.2 or 320 milliamps per metre with the 2835 LED chip measuring 2.8 x 3.5mm on an 8mm wide tape, so what does tape size play? In simple terms every LED has a working temperature range and if you exceed 60° C the LED burns out very quickly and fails, stay under that temperature and the LED lasts almost forever.
This is why the tape size is important as this is used to dissipate the heat and LED chips producing higher temperatures need larger tape to disperse the heat as some users may stick it to an excellent conductor such as aluminium which will cool he strip while other may stick it to under counter or under kitchen cupboards to give light and the wood or wood product won’t conduct the heat away so it has to rely upon the tape.

Standard numbers for individual chips are at the time of writing; 5050, 3528, 3014, 3020, 2538. 5630.

Why are the lumens important? Because they dictate the light output from a single chip and differentiate many things and to explain this we need to go back in history.
When LED strip was developed the standard chip of the day was 5050 meaning the chips were 5 x 5mm and of comparatively low light output and these were superseded by the smaller 2835 chip which produced more light from a smaller chip and this smaller chip produced less heat and the tape size went down from 12mm wide to 8mm wide. The former 5050 chip was virtually discontinued and has been resurrected and instead of containing a single 5 x 5mm chip they now contain three chips in each 5 X 5mm chip and are around 3 times brighter than the standard 2835 chip and is useful in many applications and the smaller chips play to aesthetics where they will be seen.
In many applications the actual tape and individual chips will not be seen and the actual light output is considerably more important than aesthetics as the tape is inside a housing such as a lighting batten where there may be a need to replace an old fluorescent light and instead of replacing a bulky 8’ fluorescent fitting with a much slimmer and aesthetically pleasing 8’ LED light you can replace it with a 4’ LED fitting and get more light output.

Finally we have light colour and this tends to be defined as white or cool white and warm white so what is the difference? Basically light temperature and to explain this we need to know that bright daylight is the best for the human eye and this is a light temperature of 6500K or kelvin and warm white has a light temperature of around 3000K and here is the difference, traditionally low light levels are associated with romance and to an extent they play on this as the warm white is a slightly yellow light. Daylight on a bright day is around 6500K and the human eye responds better to this and sees more and essentially the human eye reacts better to this bluer light so you get better vision from a lower powered light and for a battery powered light this is often more beneficial as you can see more for less light output so with a lower power consumption your batteries will last longer for the same visibility.

Light output is traditionally measured scientifically as lumens output per watt of electricity or how many watts are needed for a specific output such as a standard light output of 500 lumens.