Suspended Illuminated Ceilings

Suspended illuminated ceilings are available in various kit forms, all of which use more or less the same components and installation procedures. Although more traditionally associated with kitchens and bathrooms, illuminated ceilings are equally suited to other rooms in the house.

Besides creating improved lighting economically by giving a maximum amount of soft, shadow-free illumination, they will eliminate the need for future ceiling decoration — usually an arduous job. Heat losses will be reduced since the air space between the new and old ceilings acts as an insulating barrier. The space above the new ceiling will also cut down on the labour involved when installing pipework for plumbing or electric wiring; since the work cannot be seen from the room below, there is no need for you to box it in or channel out walls.

Basic components

Generally, an illuminated ceiling consists of aluminium strip sections fixed in a 600mm (or 2ft) grid formation to support light-transmitting plastic panels. The aluminium strip is available in a range of colours and the panels also come in different colours and patterns; you can use different types to create a decorative effect of your own design. Panels are mostly 600 x 600mm (or 2 x 2ft), although some 1200 x 600mm (or 4 x 2ft) types are available. Fluorescent tubes are fitted to the original ceiling and remain hidden by the panels. Cleaning Because the panels simply rest in the framework, they are easy to remove. Clean them in washing-up liquid and drip dry without rinsing. Acoustic panels These do not transmit light but provide sound insulation and also greater thermal insulation; any condensation problems will therefore be reduced. They are installed in the same way as translucent panels.


If you already have a low ceiling, the new ceiling can be fitted as close as 95mm (or 31in) to the old one — this space is sufficient to fit compact units with fluorescent tubes mounted in Terry clips. For maximum lighting effect, the space should be greater than this; ideally, 150-200mm (or 6-8in) from the light fitting — and up to 1200mm (or 4ft) in really high rooms. Above 600mm (or 2ft), increase the illumination to 20-25 watts per square metre (or 2-24 watts per sq ft). If the tubes are recessed into the original ceiling, the space can be as little as 50mm (2in).

Where it is not possible or desirable to lower the ceiling, you can form a drop section in the aluminium framework to accommodate the lighting. Various drop and split-level arrangements are possible to suit problem rooms or purely to give greater visual effect. A textured acoustic ceiling can be placed as close to the existing ceiling as you want, since light fittings will be placed below the panels.

For visual effect, coloured tubes can be used instead of. Or in conjunction with, standard white tubes. You can install both white and coloured tubes, operated independently, so a conventional white ceiling is available for everyday use and coloured effects are obtainable when you want. Coloured lamps (of 40 to 60 watts) can be used to give pools of colour; these must be fitted to allow a space of at least 75mm (3in) between them and the surface of the panels.

In glass-roofed rooms, natural daylight can be utilized as the light source. In this situation it is best to use embossed polystyrene panels (in conjunction with textured acoustic types, if you wish) since these keep down the excessive heat gains caused by the sun shining through the glass roof. They should be fixed at least 50mm (2in) below the roof.

Installing the ceiling

For maximum light reflection, paint the old ceiling brilliant matt white before fitting the illuminated ceiling. You can then fix the lighting; to determine the number of tubes needed, allow approximately 16 watts per square metre (or 14 watts per square foot). Clip the tubes to the old ceiling so they will be directly over and in line with the bridging tees or the main support tees. If the tubes are to be spaced more than 1200mm (or 4ft) apart, you should fix them so they will be above and in line with the bridging tees. Where you are using coloured tubes, position them over selected panels to create the effect you want.

Mark the ceiling height at 600 or 900mm (or 2 or 3ft) intervals on the wall right round the room, using a spirit level as a guide; if the floor is level, use a length of wood marked off to the correct height. Use a hacksaw to cut the wall angles (which support the framework at the wall) to length and fix them in position with the special nails or screws provided. If the wall is loose or of poor holding quality, use a masonry drill to make 4mm (312 in) holes and plug these to take the nails.

Standard lengths of main support tees vary according to the make of the kit; usually they are available in lengths from 1200mm to 4800mm (or 4-16ft), in 600mm (or 2ft) increments. Special jointing brackets are supplied to join standard lengths as required. After cutting and/or joining as necessary, lay the main support tees on the wall angles across the shortest span of the room. The tees should be spaced at about 600mm (or 2ft) intervals; since the width of room is unlikely to be an exact multiple of this figure, the space between the tee nearest the end wall and the wall angle will be less than 600mtn (or 2ft) and this distance must be the same at each side of the room.

For additional stability of tees in rooms over 3000trun (or 10ft) wide across the shortest span, according to the system chosen you will need to provide support from the existing ceiling. For this, you can suspend a length of wire or chain from a cup hook secured to the ceiling and attach it to the main support tee at a position recommended by the manufacturer. For example, with one kit main tees are supplied in short lengths to be joined by special clips; in this case you attach the suspended wire or chain to the top of the clip.

Place the bridging tees, which complete the framework, in position — they should rest on the main support tees 600mm (or 2ft) apart. Again, make sure the spacing between the outermost bridging tees and the wall is the same on both sides of the room. Beginning at the centre of the room, ease the panels diagonally through the grid and rest them on the tees, making any necessary adjustments to the position of the tees as you proceed. Use a hacksaw to cut the perimeter bridging tees as necessary; to cut the perimeter or edge panels, use scissors for standard light transmitting panels, a trimming knife for acoustic panels and a tungsten tipped laminate scoring tool for natural light, embossed polystyrene panels. Place the edge panels in place to complete installation.

Wiring in an illuminated ceiling

The lighting for an illuminated ceiling is provided by a number of fluorescent tubes. These can be of the batten type, which are complete fittings housing the necessary choke and starter known as the ballast unit, or plain tubes, which are fixed to the ceiling by Terry clips with push-on shrouded lampholders connected by fly leads to the prewired ballast and components housed in a ceiling-mounted casing.

Quantity and type of light

The quantity of light required is about 16 watts per square metre (or 14 watts per square foot) of ceiling area depending on ceiling height. For a ceiling of 1800 x 2400 (or 6 x 8ft), two 1200mm (or 4ft) 40 watt tubes will be. Required; for a 2400 x 3000mm (or 8 x 10ft) ceiling, three 1200mm (or 4ft) 40 watt tubes or two 1500mm (or 5ft) 65 watt tubes will be needed. You can use coloured tubes instead of white ones, but it is usually better to fit these in addition to the white ones with each bank of lights being independently switched. You can also fit inset lights with coloured lamps to throw light in various colours onto specific areas — these are also separately switched and you can use a dimmer switch if you want.

Wiring installation

Where the illuminated panels are to be fixed to an existing ceiling, the existing light point can be utilized as the source for the electricity supply. Where only one set of tubes is to be installed, no additions to the fixed portion of the circuit will be necessary since the existing lighting fitting will be replaced by, or retained with, a junction box to feed the fluorescent tubes and the original switch used.

Where separately switched coloured tubes are to be fitted, you will have to run an additional cable to the switch position and install an additional junction box. Where inset lights are also to be fitted, you will need to run a further wire to the switch position and you will need a third junction box. For the wiring, buy 1.0sq mm twin core and earth flat PVC-sheathed cable.

Wiring one bank of tubes Switch off the power and remove the ceiling rose cover. Where there are two terminals connected to the flex of the light fitting as well as to the circuit wires, these are the switched live and neutral wires from which you will make the extension to the bank of tubes. If the ceiling rose has a third terminal connected to the circuit wires but with no flex connection, this is the live terminal of a loop-in system and these two live wires are not required for the scheme; however, they must be retained to keep the continuity of the circuit. If there is an earth wire at the ceiling point (usually connected to an earth terminal in the ceiling rose), this will also be needed; if there is no earth wire, you will have to install one.

Install a junction box to feed the bank of tubes. If the ceiling rose is the two terminal type, disconnect the wires from the terminals and remove the rose from the ceiling. Fit a junction box in its place and connect the circuit wires to its terminals. Before fixing the junction box, pull up some of the slack in the cable.

You can fix the junction box to the ceiling surface, preferably screwing into a joist; but it is better to fix a piece of 150mm (6in) wide timber to two joists and fix the junction box to this. In the case of a three terminal or loop-in ceiling rose, the rose is retained as a ‘junction box’ for the circuit wires and a separate junction box is fitted to feed the tubes.

With the power switched off, disconnect the flex wires from their terminals. Remove the rose from the ceiling (with the loop-in wires still connected) and chase out a channel behind the rose to take the feed cable to the junction box; make sure this does not coincide with the position of the fixing screws. Feed one end of a length of 1.0sq mm twin core and earth sheathed cable through the back of the ceiling rose, position it in the channel and replace the rose. Connect the live and neutral wires to the empty flex terminals and the earth wire to the earth terminal (if present), after sliding on a length of green/ yellow PVC sleeving. Connect the other end of the cable to three terminals in a junction box, fitted as described. Replace the ceiling rose cover.

Fix the batten fluorescent fittings; or if you are using the Terry clip type, fit the ballast/component boxes and the Terry clip in position. You will need 38mm (1i-in) diameter clips for standard tubes and these should be positioned 100mm (4in) in from the ends of the tube. Run a length of the twin and earth PVC-sheathed cable from each fitting to the junction box, fix the cable using plastic cable clips and connect the wires to the junction box terminals. Connect the red core to the switched live terminal, the black core to the neutral terminal and slide a length of green/yellow PVC sleeving over the earth wire before connecting it to the earth terminal. If there is no earth, run a length of 1.5sq mm green/ yellow PVC-insulated cable from the earth terminal in the consumer unit to the earth terminal of the junction box.

Now fit the lamps. If you are using batten fittings, insert one end of the lamp in one end and pull the second cap outwards against the spring to insert the other end of the lamp. When fitting the lamp with Terry clips, push the tube into the clips and plug on the lampholders at the end of the fly leads from the ballast/component box.

Wiring two banks of tubes

The colour tubes should be fixed alongside but 100mm (4in) away from the white tubes. Fix a second junction box alongside the first. Run a short length of black 1.0sq mm single core and earth PVC-sheathed cable from the neutral terminal of the first box and connect it to one of the terminals in the new box. Alternatively run a separate earth lead between the junction boxes. Then run the 1.0sq mm twin and earth sheathed cable from the fluorescent lights, using the same process as for wiring the white tubes, to the second junction box. Finally run a length of red single core sheathed cable from the box to the existing switch position, unless you are also wiring inset lights; in this case, run a length of 1.0sq mm twin core and earth.

Wiring for inset lights

Inset lights are fixed to the ceiling by their flange plates. Since they will be switched independently of the other lights you will need to fix a third junction box and run a 1.0sq mm twin and earth sheathed cable from it to the second junction box. Connect the black core to the neutral terminal in the second box and the red to the switch terminal. This switch wire is looped into the spare terminal in the third box.

You can run a single core sheathed cable from the third junction box to the switch position; but since all the lighting will be installed at the same time, you will find it easier to run twin core and earth sheathed cable down to the switches, with one core for the switch wire for the coloured tubes and the other core for the inset lighting switch wire. Run a third twin and earth PVC-sheathed cable from the third junction box to the first inset light, loop it in and out of this to the next inset light and so on until the cable terminates at the last inset light.

Wiring from a separate circuit

A lighting circuit is limited to supply a maximum of 12 lamps. If the installation of an illuminated ceiling means the number of lights exceeds this figure, you will have to run a new circuit from the consumer unit. You could utilize the existing point and switch for the white fluorescent lights and supply the coloured lighting and/or inset lighting from the new circuit. Use the same procedure as for wiring the white lights and use the same junction boxes for the other lights, but feed them from a twin and earth cable running from the consumer unit. If only one other set of lighting is to be installed, run a twin and earth cable to a one gang switch fixed independently of the original switch. Where both coloured fluorescent and inset lights are installed, run a three core and earth cable down to a two gang switch unit fixed independently of the original switch.

Switch installation

If the existing single switch is of the square plate rocker pattern, use the existing one gang box with the single switch replaced by a two or three gang switch as necessary.

You can control the tungsten filament lamps of inset lighting by a dimmer switch, which is fitted to a separate one gang box. Fluorescent lights cannot be controlled by the normal range of dimmers; if you require dimming, you will have to buy special fluorescent fittings and the dimmer switch must be specifically designed for fluorescent lighting. You will also have to run additional wire from the ballast unit to the dimmer switch.

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