10

Lighting for locations and sport

Introduction

The colour of the light sources selected for any location lighting have to blend with any existing lighting but most importantly must be capable of giving good colour rendition. A prime requirement of lighting for sports is that the sources are as efficient as possible due to the reasonably high light levels required.

When we started our careers in the lighting industry, it was quite common, particularly on sports events floodlit for TV, to see several huge carbon arcs positioned on top of scaffolding towers, nowadays we would get a similar result by using 2.5 kW or 4 kW discharge PAR sources.

In a TV studio the lighting system is usually permanently in position for the operators to manipulate according to the lighting plot issued by the LD. On film stages, lights tend to be introduced almost in the same way that location lighting is used in the film industry, i.e. the type of lights used are not normally present in the studio but only placed there according to the demands of the director of photography. However, when lighting on location for film, TV, special events and concerts, the luminaires, generators, and luminaire rigging systems all have to be specially supplied. At some events, there will also be a requirement to set up a TV studio, together with designated interview areas on televised events e.g. talking to ice skaters at the side of a rink.

10.1 Location lighting

With specially installed temporary sports lighting there are guidelines for either the participants benefit or for the filming and televising of sporting events, which will have a limiting effect on the choice of luminaires and the type of rig to be used. The suspension system will be very straightforward and is there just to get the lights in the right position. The main points being that, generally, the rig should not be too obvious and that the lighting will be fairly even. The other type of lighting required which has to be more artistic and generally more uneven by design, can be for:

1. special videos and films shot on location, and
2. televised events, which may be a major outside broadcast such as the Last Night of the Proms.

The lighting can be anything from a small fluorescent source up to 20 kW tungsten sources and 18-kW discharge sources. Television and film will use tungsten and discharge lighting for location and events, with discharge predominating due to its greater efficiency; thus providing a cooler environment for the competitors or artistes. This type of lighting will be balanced by the use of dimmable ballasts, scrims and gels, and can remain on for periods of time without dynamic lighting changes.

There are several questions that need to be answered when arranging the facilities for any location and these are:

1. Location of site?
2. Has the site been used before, and if so, are there records showing rigging arrangements, electrical supply, access routes, communication facilities and points of contact?
3. How much time is there to rig and de-rig the event?
4. Access to and from site?
5. There will probably be a need for a truss system to be erected to support the luminaires, sound systems etc. additionally there could be a requirement for scaffolding platforms for follow spots, etc.
6. Where is the technical equipment to be situated, i.e. lighting, sound and cameras?
7. Is there a requirement for a control position – if so, where is it in relation to the other equipment?
8. Does the location have a sufficiently large power supply or does it require power generation equipment?
9. If generators are required, where can they be positioned, bearing in mind they are very heavy and fairly noisy devices?
10. How do we get power from the generators to a fairly central position where it can be distributed throughout the venue or location without large volt drops on the long cable runs?

Many small outside locations used for film and TV probably only require the use of a few luminaires and the majority of these will be used on stands. Where more complex arrangements are required for this type of location, it is possible to hire trucks complete with generator and a working platform capable of going up to great heights, to enable lights to be positioned very high above a scene. These can vary from a single Fresnel discharge source on a jib arm through to more powerful sources such as the tower trucks made by Musco Lighting of America capable of raising an array of fifteen 6 kW discharge sources to around 35 m. Because each 6 kW luminaire is an open-faced fitting, its light output is more than twice that of a 12 kW Fresnel discharge luminaire. The trucks, which are fitted with soundproofed generators, weigh around 33 tonnes; the boom extension is fitted behind the driver's cab and towards the front of the generator. This obviously gives a very stable base for the heights required, with an extremely low centre of gravity. The lights can be controlled from a small handheld remote control unit or by an operator with levers at the base of the boom arm; and each light can be panned through 359°, tilted through 220°, flooded and spotted. Additionally, the boom arm is capable of rotating 180° on its base.

10.2 Electrical distribution

When designing a power distribution system various requirements will have to be taken into account. These are:

1. What are the production requirements?
2. What are the site conditions?
3. The design of a safe and suitable electrical system, which will have to take account of the fact that some systems may have large out of balance neutral currents.
4. Ensure that any installation meets the requirements of the local authorities such as the Fire Brigade, etc.
5. In areas where lightning is a high risk, it is essential that precautions are taken to prevent any unnecessary hazards.

The various connectors used must be approved to either a British Standard or an International standard to suit its actual use. The main requirement with connectors would be that they should only be used in association with a correct pin connections and relevant colour codes, etc. The main power distribution cables generally use large single pole connectors due to the high currents involved and it is essential to identify each of these connectors clearly to show whether it is a phase, neutral or earth conductor. It is fairly obvious that any misplugging can cause a huge fault, or a very dangerous situation. Several modern distribution systems do have sensing circuits to prevent any misplugging. Several distribution units in use today have all the necessary intake switchgear and sub-distribution fuses or mcbs contained within one unit, which makes the whole process so much safer by reducing the amount of inter-connections on site.

Generally, multicore connectors and cables are used for circuits up to 125 A, above this point single core connections are generally used. An important factor with the cable rating is that they may be taken to areas where the temperatures are extremely high and due to the installations, will probably be bunched or grouped in close proximity which can cause problems, and this is a factor which must be taken into account by the designer concerned. All items used on the temporary installation should have been tested for electrical safety prior to being delivered to site; they should be marked that the test was satisfactory. When routing the cables, it is essential when in the areas where the public are, that the cables are routed carefully, possibly up and over gangways so that there is no danger of anyone tripping over cables. A problem with temporary cables is that they may have to go through various doorways, etc. and it is essential that they would not break any fire regulations by breaching openings in the building which should be closed during a performance or normal working conditions. The power will be either from the public supply or from a generator and the distribution system will feed dimmers and other subsidiary equipment, which may be located in many places within the temporary installation. It is essential that all feeds to all these items of equipment are adequately fused or have the correct mcbs fitted to ensure protection for the cables and equipment. One of the problems with temporary installations is the variety of weather that may be encountered. For instance, outside events in very humid or wet conditions would no doubt require special precautions to be taken to prevent any safety hazards and the use of RCDs is encouraged. Most modern distribution units are fitted with RCDs and to prevent nuisance tripping they are also fitted with a bypass system accessed by the use of a key.

It is essential that when the temporary installation is complete it is fully checked to ensure, as far as possible, that all connections and equipment are installed correctly prior to the application of power to the system.

Multi-way connector systems together with multicore cables are used to supply from dimmer racks to points on a truss where ‘fan out’ cables are used for six dimmer circuits, each comprising a live, neutral and an earth connection.

With permanent installations, purpose built switch rooms and areas which are used for electrical supplies, can be built in such a way that they are not capable of being entered by members of the public. On outside broadcasts, locations or special events where temporary lighting is used, it is essential that the public are kept away from any source of electrical danger which might come from the distribution units or cable system. Most supply systems encountered are ‘star’ connected three-phase systems, but it is possible on some locations, to encounter ‘Delta’ connected systems and the best method to overcome any difficulties with the connected equipment is to employ ‘Star’ output transformers which are fed from the ‘Delta’ supply.

If the power requirement for additional lighting in any venue or premises is not too great, it is possible that there will be sufficient capacity on the house supplies to allow the extra luminaires to be used. However, in the majority of cases there is no slack capacity and the generator will have to be employed. Whatever the system of obtaining a power supply the fact is that it needs to be adequately fused, the cables need to be of sufficient size and they need to be run in such a manner that they do not cause danger to members of the public and/or artists. In the past, usually three-core cables were fed to each luminaire, usually from some switchgear or dimmers. The pop industry found this was too time consuming when they were on the road with the large rigs employed and resorted to multi-core cable systems feeding banks of luminaires. However, there is a finite limit to the size of cables used, due to the weight and flexibility. If they are heavy, it is important that the actual runs of cable, when coiled, would be within the handling capability say, a rigger or sparks on trussing etc. An important point to bear in mind is where are dimmers, if used, being placed in relation to the luminaires themselves. Obviously long cable runs should be avoided if possible and additionally, the power loads shouldn't be too far away from the generator due to the need to have large cables coming through any premises. Distribution can be broken down into three areas:

1. The main intake, where large cables are taken from a generator into subsidiary switchgear, probably of around 400 A per phase and then distributed from these units protected by mcbs.
2. To smaller units placed strategically in the premises and probably protected at around 125 A.
3. Finally these circuits would feed the dimmer racks with individual outputs anywhere between 2kWand 10 kW.

Special arrangements have to be made to feed the ballast units associated with discharge sources. As well as the power feeds, there will also be a need for the control cables used with automated lighting systems, dimming shutters and hoist motors all placed in the temporary grid system. With tungsten lighting on dimmers, a power factor very close to unity will be achieved most of the time, however if using discharge lighting without power factor correction, it is possible to find that there are large neutral currents flowing and this can cause problems with the distribution system. Normally, with a three-phase supply if the load is balanced uniformly across the three phases, there would be no need for a neutral return, but with out of phase currents there is a need for a neutral. It's no good providing a small neutral in relation to the large phase conductors, it is essential that the neutral conductor is the same size as the phase conductors, and it may be with high harmonic content the neutral has to be twice the size of the phase conductors.

10.3 Generators

Generators come in various sizes, from the small Honda sets giving a few kilowatts to the large 1000 kVA generators. All modern generators are driven by diesel and are provided with large fuel tanks so that the generator can run for many hours without being replenished. One of the problems with diesels is that if it runs out of fuel, it would be necessary to bleed the fuel lines to allow the diesel to run again. On occasions, when it is necessary to run generators for long periods of time without switching off, it may be necessary to make special arrangements to introduce fuel from an external fuel tank system. The generators are normally three-phase and require that the phases are fairly well balanced to ensure that the diesel runs smoothly; the diesels used for the entertainment industry require to be silent running. It is essential that the frequency of supply is kept stable, and this is usually done by fitting electronic governor systems. Normally, the rear of the generator contains a distribution panel which is fitted with voltmeters, ammeters and the various switches required to run the diesel itself. The normal procedure is to wire to the generator from the local distribution units, check all the electrical system is OK and safe and then run the generator, when the generator is running the main switches are applied and electricity is supplied to the system.

Although a generator may be rated at say, 1000 kVA, if this is not feeding units which have a good power factor, it can be that the output is considerably reduced and in the past with using discharge sources with standard ballasts, a 1000 kVA generator may be only worth 700 kVA with all the luminaires connected.

10.4 Trussing and support systems

Truss used for suspension systems comes in different sizes and lengths with a variety of joining pieces to enable intricate arrangements to be built. The physical size would be determined by the weight loads such as cables and luminaires imposed on the truss. The larger the load, the larger the cross section of the truss. The length of section will be decided by the maximum deflection under a load that can be applied safely without the truss being deformed. The size and length of truss may be decided by the ability to suspend only from a few points rather than regular intervals, i.e. a fairly long truss only suspended at its ends will obviously have a limit of deflection due to the lack of a central suspension point.

The first requirement of truss is that it should be lightweight but capable of taking quite high point loads on the structure with a pretty reasonable overall SWL. The sections have to be small enough to be manhandled and transported; they also have to be capable of being assembled quickly and safely. Truss comes in various sizes and various lengths. Having established the pattern of truss required, it is now essential to lift it to the height required in the venue by using inverted chain hoist motors, with capacities anywhere between 1/8 and 3 tonnes, the most favoured of these being 1 tonne. Obviously with just one straight section of truss, it may be possible to hoist it into place with two motors, but the first requirement of hoisting is the fact that the motors must run synchronously together so that it is easy for the operator on the control unit at floor level to ascertain the correct height and enable the unit to be positioned accurately. If three motors are used on a straight section of truss, it is essential that all three take the load simultaneously and no one motor ends up taking the majority of the load. As the rigs become more complex it maybe that several motors have to be used simultaneously to lift a pre-arranged pattern of truss to a set position above the performing area.

Any chain hoist motor unit will probably be capable of up to 40m of lift, be protected for overload and have upper and lower limit switches fitted to ensure safety when working with these units. They may be used on either single or three-phase supply; the majority being three phase.

The vast majority of the lights used on truss are Parcans, and these are usually in pre-wired groups on short bars, easily attached to the truss itself, and capable of being plugged to the multicore electrical feeder system very rapidly. However, there is a need to identify all the feeder cables so that the console operators concerned will know which dimmers control which lights. In addition to the Parcan, there is generally a multiplicity of automated luminaires to provide dynamic lighting effects on the set and there also may be a requirement for laser projection. Sound reinforcement loudspeakers may also be required to be rigged on the truss.

In addition to the chain motors which takes the truss to high level, once in position, it is essential that extra bonding is provided so that the system is absolutely safe. In addition to bonding the truss by a secondary means of support it is essential that all luminaires attached to the truss are also safety bonded to avoid any accidents, either to the performers, audience or technicians involved.

10.5 Lighting for sports

Most modern large indoor arenas will have floodlights fitted which provide lighting levels quite adequate for modern TV and usually are designed to do just this. Because the lighting levels for TV coverage are quite high, some venues will have a three-stage floodlighting system which provides for normal level of play, expert level of play and for TV coverage. Most floodlights have discharge lamps fitted because of their greater efficiency and in the past did not always have high colour rendition properties, however, most systems installed today will follow the guidelines set by the Sports Council in the United Kingdom and the CIE (Commission Internationale d'Eclairage) in Europe.

Floodlighting requirements for sports

(Extract from Sports Council Guidance Notes for Floodlighting)

Horizontal values at ground level

Lux-Illuminance level. Ra-Colour rendering

Floodlights consist of groups of luminaires aimed at the playing area with over-lapping beams to achieve a smooth result. In the past most of the floodlights were set by a team working to a drawn plan issued by the lighting designer after some laborious calculations, with luminaires having aiming sights. Today, it is more than likely that all the lighting calculations will have been done on a computer which then produces data which allows the luminaire settings to be pre-configured at the manufacturing plant. Once on site all that is necessary is to erect the masts at their designated positions, fit the luminaires and align them to the pre-set marks.

Lighting at sports events is quite often the application of reasonable illumination in a studied way onto an area. The skill generally is positioning trussing and lights so that they do not interfere with the competitors’ eyeline and they also give a reasonable result on the playing area without affecting the spectators’ eyeline.

Beyond the needs of the spectators, there is a need for the lighting levels to satisfy film and TV cameras and this is particularly true today when much sport is televised. In Europe the CIE have laid down guidelines for sports stadia lighting. These days, with many cameras used on sporting events, particularly small portable cameras that go anywhere in the playing area, any individual camera must have sufficient light level for its requirements wherever it may be. The Sports Council recommend that the Colour Rendering Index (Ra) for sports at the highest level should be at least 60. However, it is generally accepted that the Colour Rendering Index for film and TV coverage at the highest level of competition should be at least 65 and this is the recommended figure given by the CIE.

The CIE also state that vertical illuminance should be used to assess the lighting for good quality film and TV pictures. Vertical illuminance is used because all objects of interest are generally vertical to the playing area. The positions at which the vertical illumination measurements should be made depends on:

1. If the cameras are positioned along one side of the playing area then the incident illumination on the plane only facing the cameras has to meet the required light level (Figure 10.1).
2. Where the cameras are positioned anywhere around the playing area, it is essential for the illumination in all four vertical planes to meet the required levels (Figure 10.2).

Figure 10.1 Single plane incident light readings

Figure 10.2 360° incident light readings

In isolation, each camera trained on a particular area may be able to correctly expose for a picture but the overall effect of the lighting has to be reasonably consistent to allow for those cameras which follow the action, for example all around a running track, and a figure of around 0.4 minimum to maximum vertical illumination is usually acceptable. As the illuminated horizontal area can form a large part of the field of view of a camera it is essential that a good balance is maintained between the vertical and horizontal lighting levels and a figure of between 0.5 and 2.0 is considered satisfactory. This figure is obtained from the ratio of the average horizontal illumination to the average vertical illumination. Acceptable illumination varies from 300 lux to around 1400 lux for events at the highest level such as the Olympic Games.

The figures given above reflect the illumination levels required for sport, they do not give any guidance as to glare and in practice most of the sports governing bodies have their own recommendations as to the way they prefer their individual sport to be lit. A good example would be fencing, where due to the nature of the sport, any small interference with the participants’ eyeline from the lighting can cause problems. It is therefore preferable that the lighting is arranged parallel to either side of the fencing mat and sufficiently high to be out of the participants’ eyeline.