Installing Fluorescent lighting

Fluorescent lighting is glare-free and casts no hard, irritating shadows. It is therefore ideal for certain areas of the home, particularly the kitchen, bathroom, workroom and garage.

M any people have mixed feelings about fluorescent lights because of the nature or ‘colour’ of the light they emit. Admittedly they are not tho best form of main lighting for living or dining areas as the light is harsh compared to ordinary tungsten filament light and doesn’t give a relaxed atmosphere to the room. Nevertheless, they are ideal where good all-round lighting is required.

Fluorescent lighting can be fitted at any lighting point. However, an ordinary ceiling rose on a loop-in circuit will require some minor modification to the fixed wiring. This is not a difficult operation.

Types and uses

There are two basic lypes of fluorescent fitting – linear and circular – and both are made in a range of sizes. Circular tubes, in particular, are becoming more popular as they greatly improve the light output from a ceiling point and can be fitted flush to the ceiling and disguised with an attractive glass diffuser. The straight tubes likewise spread light evenly in a room, again often aided by a diffuser. In this case it’s usually a corrugated or dimpled cover which is clipped over the fitting.

Fluorescent lights come in a variety of sizes; as a result they can be used for all sorts of purposes in kitchens, bathrooms, and in more specialised areas.Forexample, small tubes are ideal for concealed lighting in alcoves and can be hidden behind pelmets or baffles to highlight curtains drawn across a window. Sometimes they are used to feature cornices against the ceiling. There is also a type available which resembles a tungsten filament light bulb and can be used in an ordinary lampholder. And as the tubes last for 5,000 to 7,500 hours -about five year’s average use – this more than compensates for the extra cost.

Installation and running costs

Fluorescent lights are more costly to install than a normal light, but because they are more efficient at turning electricity into light than a filament lamp they are cheaper to run. And they also have a longer life. In fact a100W filament lamp will give light for ten hours for one unit of electricity (1 kilowatt/ hour) while a 1500mm (5ft) tube will give four times as much light for the same cost over the same period.

The fluorescent fitting

There are two parts to a fluorescent fitting. The lamp itself is a long, thin glass tube, which is coated on the inside with a powder that fluoresces – gives off light – when the fitting is switched on. The tube contains argon gas, which is similar to neon, and a small amount of mercury, and at each end there is a tiny heater (electrode) which is coated in a special chemical. In some fittings there is more than one tube.

The other part of the fitting is the control gear. This is made up of several different components including a starter and ‘choke’ or ‘ballast’, and is responsible for starting up the light when it’s switched on and controlling it when it’s operating.

Most manufacturers sell an integral unit which incorporates both a tube and linear metal box designed to take the control gear. But they don’t always have to be together. In fact, in some situations it’s probably a good idea that they aren’t. If you want to highlight some curtains, for example, you could conceal the tube behind a pelmet board or a baffle, holding it in place with spring clips about 150mm (6in) from the material. It should be connected to the control gear, which can be mounted on a solid surface nearby, using 0.5mm2 (3 amp) or 0.75mm2 (6 amp) flex. As the choke can <&&& gel rather warm, the control gear should have some ventilation.

Given the positions where most fluorescents are used, it’s unlikely you’ll want to be able to control their brilliance. If you do you’ll need to use a special dimmer and modify the fitting.

How the light works

In an ordinary tungsten bulb electricity flowing through the filament causes it to heat up to a white heat and so emit visible light. In a fluorescent tube there’s no filament, but the electricity flowing between the two heater elements at each end causes the mercury vapour in the tube to emit ultraviolet (invisible) light. This is converted to visible light by the fluorescent powder on the inside of the tube.

In order to get an electric current to flow in the tube a high voltage is needed initially when the light is switched on. And it’s the function of the choke and starter to provide this. At the same time the starter also has to heat up the elements. Once the light is operating, the starter switches itself off while the choke and power factor correction capacitor (PFCC) regulate the current flowing through the tube.

There are two types of starter. The thermal type has a tiny heating element which acts like a thermostat and turns off the current in the starter circuit when the elements are hot enough and current is flowing in the tube. The more common starter is the two-pin ‘glow’ type which doesn’t have its own internal heating element.

Quick-start fittings

Some fittings have ‘quick start’ ballasts that don’t need a starter, but a special tube is required with a metal strip running along its length, which is earthed at the lampholders at either end. When the light is switched on the current passes down the tube immediately – so there is no flick-flick effect or delay in the tube lighting. This type of fitting needs to be earthed. The manufacturers’ catalogues usually contain details and circuit diagrams.


Linear tubes range in length from 150mm (6in) to 2400mm (8ft). Tube diameters are

– 15mm (5/ain) – miniature.

– 25mm (1 in) – slimline.

– 38mm (1 Vfein) – standard

Light output varies from 4 to 125 watts.

Circular tubes are made in diameters of:.

– 300mm (1 ft) rated at 32 watts.

– 400mm (1 ft 4in) rated at 40 and watts.

The most popular tube sizes for the home are 1200mm (4ft) with a light output of 40 watts and 1500mm (5ft) with light outputs of 65 and 80 watts. These are sold complete with their controls and usually a baffle or diffuser to disguise the tube. Apart from the tubes which give off ‘white’ light, others are available which give off pink, red, green, gold and blue light.


Most fluorescent lights use the common bi-pin type of tube. There are two pins at each end which push into the sockets of the fitting to make the connection. The other type of tube is the bayonet type with a connection similar to that of an ordinary light bulb. It’s now only found on 1500mm (5ft) 80W tubes.

A 40W tube 1200mm long will give adequate general lighting.

Colour range

Fluorescent tubes are manufactured to give off different types of light. In all there are 13 different colours to choose from. These range from the very cold white ‘northlight to the warmer yellow colours. Most of the fittings sold in retail lighting shops are supplied with a tube marked white’ – a colour that isn’t really warm when compared with the yellow light given out by an ordinary filament lamp. The tubes giving a yellow light are listed as ‘de luxe warm white’.

Some fittings such as the very useful circular fluorescents with their diffusers and some of the 25/26mm slimline tubes are available in ‘warm white’ or the colder ‘natural’. The very neat 15/16mm miniature tubes are available in three or four colours, but not in ‘de luxe warm white’. ‘Warm white’ tubes are ideal for the kitchen, but they’re not really acceptable for living rooms except for lighting small areas displaying ornaments or paintings, for example. Here the colder colour of the fluorescent can be compensated by tungsten lighting elsewhere in the room. Colours such as ‘daylight’ and ‘natural’ are not really suitable for the home except for display cabinets.

Installing the fitting

You can install a fluorescent fitting almost anywhere instead of an existing tungsten filament lamp. If you want to connect the fitting to an existing lighting point, you’ll first need to inspect the fitting or rose that’s already there to see how the circuit is wired. If there is only one cable going into the rose or fitting on the fixed wiring side – ie, there’s one black and one red insulated core and possibly an earth wire – then the circuit is wired on the junction box system. All you have to do when putting up the fluorescent light is to connect the cores to the relevant terminals in the fitting – black to the ‘N’ terminal, red to the ‘L’ terminal and the earth (which should be sleeved in green/yellow PVC) to the ‘E’ terminal.

However, if you’ve got loop-in wiring where there are two or more cables going into the fitting or rose, then some small modifications are necessary as there are no loop-in terminal facilities on a fluorescent fitting. All you have to do is to draw the cables back into the ceiling void or loll space and fit the cores to the relevant terminals of a four-terminal junction box. You then have to run a short piece of 1.0mm2 two-core and earth flat PVC-sheathed cable from the junction box to the fluorescent light and connect it to the terminals.

If, as in many circuits, there is no earthing at the lighting point, it’s necessary to run l.5mm? green/yellow PVC-insulated cable from the fluorescent fitting back to the earthing terminal block in the consumer unit.


Turn off the power at mains when carrying out repairs other than changing the tube itself. FAULT Tube flickers and is reluctant to light, or tube glows at each end but fails to start.

Solution Faults could be due to malfunctioning starter; if so fit hew one. Or it could be an ageing tube. Look for telltale signs of blackening at ends of tube; if present fit new tube of same size and type. FAULT Tube glows at one end and flashes.

Solution Check tube connections. If pin holders damaged or bent, fit new holder. FAULT Strong oily smell. Solution Check the choke for signs of burning and replace it making sure you use the correct type to match the wattage of tube.


A simple operation – locate the starter, push in and twist anti-clockwise to remove. Replace with a new one of the same type.


With a bayonet-type fitting (1), push in and twist the tube against the spring-loaded lampholders. With a bi-pin tube (2), simply pull back one of the spring-loaded end brackets.

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