15

Maintaining and hiring lighting equipment

15.1 Standardisation for maintenance and spares

Maintenance can be in house or in the case of hired equipment, the hirer does the maintenance. What follows applies to anyone concerned with maintenance. One of the problems with a variety of equipment used, is the fact that to maintain it requires different procedures for each type of equipment. This generally poses a problem for the maintenance engineer and, secondly it can lead to items being overlooked by the staff being unfamiliar with all the equipment concerned. It therefore follows that is advantageous to keep the various types and makes of equipment to an acceptable minimum.

15.2 Maintenance rooms and test equipment

If we are given an opportunity to plan our own maintenance area, what should we look for?

The first requirement is an area large enough to store the spare lights and equipment plus enough room to stack the equipment requiring repair, leaving room to test luminaires and have enough racking for spares and consumables such as lamps and filters. Obviously we would require a good electrical supply terminated into a purpose built distribution board which will provide all the types of socket outlets required together with a three-phase outlet; a large bench, with an equally large vice, covered in a thick linoleum that is also a good insulator. A large lock up cupboard stocked with taps and dyes and nuts and bolts of all sizes, complete with all of the normal tools including an electric drill, soldering irons large and small and an adequate supply of various plugs, sockets and cables. Test equipment should also include a good quality multi-meter, an incident light meter and a tri-stimulus colour meter to perform light tests. To comply with the Electricity at Work Regulations, each piece of electrical equipment must be entered into a register and periodically tested. Purpose built electrical test instruments are available offering all the test facilities required and are a good investment for everyday use and to use for the periodic tests. To be given these conditions and a good lock on the door, is no more than the electrical staff deserve to enable them to keep a well ordered house in good working condition.

15.3 Luminaire maintenance

A common misunderstanding of maintenance is that the electrician walks round with a duster and flicks dust from lights and repairs the ones that do not work. Nothing could be further from the truth. Electrical maintenance is a legal requirement, laid down in the ‘Electricity at Work Regulations’.

Over and above the electrical safety tests, there are three main problem areas to be considered when carrying out luminaire maintenance: heat, mechanical damage and the ingress of dirt. It is inevitable that luminaires are going to attract the dust and dirt that is in the air by virtue of the fact that the instrument is designed to have a cold air intake to cool the lamp and electrical equipment, which also sucks in the associated grime. As it does so, it deposits the dirt on the lens, reflector and any other surface which is subject to change of temperature. Therefore, periodic cleaning is required to maintain the efficiency of the luminaire. Most reflectors are made from brightly polished anodised aluminium. These are surface reflectors and should only be cleaned by wiping them with a damp cloth and liquid soap, a conventional wipe down with a wet rag afterwards to remove the soap will suffice and dry with a lint free rag. The same method can be used to clean the lenses, however, in the case of the tungsten halogen lamps which have a large deposit of grime on them, these should be wiped clean with alcohol and then polished with a clean lint free rag. Finger marks must be avoided on tungsten halogen lamps to prevent the fingerprints becoming etched into the envelope when they are hot, causing hot spots which can collect extra heat and form a blister on the envelope.

Regular examination of the internal cables, which are flexed when the unit is focused, are needed to determine if the insulation has been damaged. Switches and lampholders are a target for excessive heat. One indication of a lampholder overheating is to remove the lamp and inspect the pins. If they show signs of ‘arcing’ then the lampholder must be replaced, because if a new lamp is inserted into a lampholder that already has arcing on the contacts, it will transmit the same problem to the new lamp. The safety bond must be visually inspected for damaged or frayed strands. Any bond or chain must be replaced if it has arrested one fall of the luminaire. Barndoors and colour frames are retained by safety catches which must be in good working order. If cables are to be replaced they must be of the recommended temperature range, do not be tempted to use just any old cable. Lenses must be examined for chips or cracks, the most obvious place is around the edge of the lens which when continuously heated and cooled progresses the chip into a crack and the lens will ultimately fracture. Change any damaged lenses. Look for dents in the housing that could cause problems to the electrical internal switches and wiring. The yoke must be examined to determine that it is mechanically sound.

15.4 Suspension system maintenance

Trusses, counterweight bars, motorised barrels, telescopes and pantographs are basically the same device, a means of supporting luminaires from above with variable height. They may employ electrical drives, with various sensing switches together with cable support systems or alternatively, spring balanced. We can therefore generalise about support systems and state that a secondary means of support should be provided. This usually takes the form of a wire cable (safety bond), as a means of arresting the device if the primary means of support is broken. Therefore the first step in mechanical maintenance must be to inspect these areas which provide the ultimate safety.

Well designed winches allow inspection of the cable termination on the winding drum and at the bottom end of the cables. Look for loose or frayed ends, examine the whole length of the cable as it is wound in and out for any loose threads. If any such signs are seen, the cables must be changed. Each lifting apparatus has a SWL stated on it, a periodic inspection must include the application of a test load to determine that the unit is safe. Many insurance companies require such tests annually. Most designs employ a top and bottom limit, the unit should be run through the whole range to determine that both limits are working and also the overload and underload limits. These are normally provided to switch the device off in the event of it picking up an additional load such as a piece of scenery or a safeguard against the operator placing too many luminaires on the barrel. The underload switch is required if the luminaire is lowered onto the top of a set where cable would be spewed out until the luminaire toppled off the set and presents a real hazard. This test can easily be simulated by lowering the luminaire onto a rostrum where it should cut out immediately it touches the floor.

In the case of traversing monopoles and pantographs, they are normally fitted with end stop switches for traverse, which must be operated and the electrical cables should be examined for damage, particularly in the case of pantographs where cable are laced up the side of the links and can easily be caught between them. In general gearboxes should not require maintenance, unless they have been stripped down for repair. Care should be taken on the type of grease or oil used, some types of gearbox rely on a heavy lubricant to help them to become self sustaining to avoid the luminaire running away under a no volt condition. Any lubricants used must be at the recommendation of the manufacturer. A good guide to all lifting devices is that two turns should be left on the hoisting drum when the device is at the bottom limit. This will determine that the cables retain the load and not the end fixing. The cables used in lifting devices are special and normally of a flexible nature. Only use the manufacturers’ replacements. Pantographs should be inspected for mechanical damage of the links and the hinge pin retaining clips, these have been known to pop off and not affect the operation until the pin slides out. The springs used on pantographs normally have a 10000 cycle working life, this doesn't meant they will fall to pieces in 10000 cycles but an early warning of fatigue can be found by inspecting the edge of the springs, which show small cracks developing along the edges towards the end of life. Any sign of fractures, the springs should be replaced. Extreme caution must be taken in removing the springs from pantographs, with a pantograph on a bench, the spring should be pulled down by the ring provided and allowed up slowly until it touches its winding drum. In this state, the spring will be stationary and can be released. The assembly can be removed from the pantograph. Under no circumstances attempt to remove the spring from the drum, it is under considerable tension and can only be removed from the drum by the manufacturer. Barrel roller trolleys have stops screwed to them which engage under the barrel to prevent the trolley jumping off. On inspection ensure that the stops are present and undamaged. Where monopoles are concerned, sticking tubes are often caused by external damage. If this is the case, it is recommended that a complete set of tubes is replaced, in view of the fact that these are mated during manufacture for not only size tolerance, but the bow that occurs in their length. Any attempt to replace one particular tube could result in many hours of work and problems of fit and alignment that you were not aware of.

15.5 Holding spares and expendables

The seemingly simple task of holding spare parts and replacement items is anything but simple. The problems are mainly trying to identify the parts required and the quantities to hold in stock and monitoring the usage of expendable items.

Major items of equipment, such as winch systems, dimmers and luminaires will be changed with replacement of worn out plant programmes and these may vary in length of time from a 7 to 20year cycle. However, on a day to day basis, we have operating costs that are concerned with the maintenance of plant and the use of lamps, filters and certain types of accessories.

With a new installation it is a good policy to ask the manufacturer for a ‘spares list’ identifying all of the likely parts that will be required to keep the product in good repair. This request in itself, causes some manufacturers to research their own products to determine the likely spares requirement for the future; whereas other manufacturers produce pictorial spares sheets, with photographs of the parts for easy identification. This practice also helps the user to determine his particular model in the years to come after the product has undergone several modifications and upgrades, and also overcomes the language problem when trying to describe the parts that are required. If your make of equipment does not provide this luxury it is expedient to ask for a written parts list which will identify your model and the parts required at that point in time.

If you are fortunate enough to be at the planning meeting when the products that are to be ordered are chosen, then it will be expedient to include the spares at the same time and as a condition of the original purchase. That part is easy. The question is: how many spares should be held?

Manufacturers have often taken part in discussions with the user to determine a sensible spares holding. In the first place this can only be an educated estimate from past experience and a percentage applied to the purchase order. A typical spares list for a luminaire could be as follows, with a percentage applied for orders from 100 to 300 units.

This could be a good starting point but don't forget that paradoxically, the older the equipment gets, and therefore the more likely to require spares, the less likely they are to be available; because the manufacturer has moved on to other designs. However, most reputable manufacturers keep spares for seven years from the first model –so beware if you have purchased in the last year of manufacture.

Holding spares in an existing installation reduces the problem of how many to stock, because a good record of purchases over the years will give a good guide to the likely requirement. The main problem is availability, because many luminaires are kept working long after their useful life. If this is the case and the original equipment manufacturer cannot supply the spare parts, there are specialist companies that carry out repairs and make special parts for old products.

Expendable items are much easier to predict. With a good record of purchases a working quantity can be arrived at. Some of the most expensive items are the lamps. In many organisations the advent of computer databases has enabled the recording of faults and replacement items a relatively easy chore, which enables an analysis to be made of problems encountered. Fortunately, there are several main stockists that hold the large range of lamps used in TV, film and theatre, so the spares holding can be reduced to a nominal amount to cover day to day needs and calling on the stock of the main stockists for unscheduled requirements. From records, a guide of lamp usage in theatre and TV studios is approximately 1.3 lamps per year per luminaire. This is assuming that the lamps are supplied from dimmers. In the theatre the lamps will be providing different light levels, but the average dimmer output level could be similar to that adopted in TV, where it is common practice to line up the cameras with the dimmers set to level ‘7’. In both cases this has the effect of greatly extending the life of the lamp. However, in film lighting the lamps are normally run at full voltage, resulting in a much shorter life. Typically for a tungsten halogen lamp, rated at 3200 K, this is likely to be from 200 to 400 hours. One way of easing the pain of the lamp costs in the first 2 years of a new installation is to order two lamps for each luminaire at the same time that the equipment is purchased. In this way it is paid for out of the capital investment and does not come out of the expendable budget. By the second year, sufficient experience will be gained to determine a fairly accurate expendable requirement.

Whereas lamp manufacturers supply figures of typical life in use, filter manufacturers don't. This is obviously extremely difficult to do, because the life of filters is dependent upon the light source being used. However, from the customers’ point of view, it's very useful to do some tests to ascertain which filter material has a good life. This can be done very simply by putting up similar colours on the same light source and seeing which one deteriorates the most.

Stocking colour filters can be a big problem; the variables being 100 different colours sold in sheets and rolls. Although there are several good stockists who can normally respond quickly to your needs, it is expedient to keep a working stock of filter to call on. To remove one of the variables, it is normally a good practice to stock colour filters in rolls, this makes racking simple, with a colour swatch and number attached to the end of the roll. Rolls are also more economical because different sizes can be cut with the minimum of waste. However, the second variable of 100 colours needs a lot more thought. If one applies the 20/80 principle which seems to work in most cases, then 80% of the filters used will be in 20% of the colours offered. This would appear to be a simple solution; just stock the 20 most popular colours. After much discussion and heated exchanges with the LDs, you might arrive at a compromise short list but be prepared for a long and arduous debate.

Filters used for colour correction are, of course, out of this category and are stocked separately as the need dictates.

Some accessories disappear as if they were expendable items and require special attention, otherwise a constant state of annoyance will persist. Barndoors usually suffer from damage preventing them from rotating and the flaps suffer from that infuriating malady known in the trade as ‘a droopy flap’. This is when the hinges have become so weak that they cannot support the weight of the flap. Replacements will save a lot of aggravation between the LDs and the electrical staff. Safety bonds have a habit of disappearing, whether an alternative use has been found for them that we have not yet discovered or a private hoard is hidden somewhere in the building, we will most likely never find out, but one thing that is certain is that every luminaire must have one to meet the safety requirements, so good replacement stocks must be maintained. Colour frames suffer from the same problems but have the additional requirement in theatre to be ‘gelled up’ between shows, so a complete set of spares is required as well as replacements.

Control and dimming should not require a large spares stock; the modern systems are very reliable and offer electronic card replacements and dimmer modules which should suffice. However, do not forget that when a tungsten halogen lamp ends its life with an arc-over across the filament, that it draws a large current and normally blows the fuse, so it is necessary to keep a good stock of spare fuses. Finally be sure that you have made your case for expendable items by submitting your budget for next year in plenty of time. No one else in management is going to remind you to spend their money.

15.6 Monitoring equipment usage for replacement programmes

It is quite common for a lighting manufacturer to be asked for spares to repair a luminaire that is 30 years old, not for a sentimental enthusiast to restore the instrument as an antique, but by necessity to keep the luminaire working long past its useful life. It is normally not too difficult to get management to replace a control system after some years of service, because there is always a good case for having the latest development in ‘thingummy bobs and wotsits’ that the designers of lighting control systems are constantly adding to their products. The simple lumi-naire or lifting device stands very little chance of becoming more desirable because it is a new model so the attitude of some management is ‘light still comes out of it’ or ‘it still lifts up and down, doesn't it?’, mainly brought on by the sudden realisation of a big capital investment. Whilst we can blame the management for not wanting to invest more money, what have we done over the preceding years to develop a replacement programme. In most establishments, the accountant will depreciate the capital equipment by 25% per year, in this way the book value will reduce to 23.72% of the original value in 5 years.

This method of amortisation will never remove the item from the books, but will show the management that the equipment that will be scrapped when it is replaced has very little capital value so that it can be written off. It is therefore a good practice to keep records of your own in the maintenance department of purchases and the date and cost, and make this information part of your inventory. To support your argument for replacements, you should keep a record of breakdowns, cause and effect and so build up a case for replacements because of the nuisance to the production. Other factors are its size, weight and performance compared with a modern equivalent. In this way additional items can be introduced into your capital replacement budget each year in the hope that some money will be made available. If this is not forthcoming, keep the running total and add to it each year, then if you eventually get a percentage of your requested capital investment allowance, it will at least be a percentage of a much higher figure. The last question that management cannot ignore is ‘does it conform to current safety standards?’

15.7 Hired equipment

At some time or the other, most lighting people will require the services of a rental company to supply the extra equipment for a particular occasion or to provide a total installation on a temporary basis. There are many good rental companies available, providing an excellent service to the industry. Rental companies tend to specialise in film, TV or theatre; normally dictated by the specialised equipment required in each of the lighting disciplines. A film company normally registers a film as a business name and trades as a Limited company for the duration of the film. This sometimes makes it advantageous for equipment and cameras to be hired from a rental company and are therefore costed directly to that film. If the equipment had been purchased, it would present a problem at the end of the film of what to do with the equipment. In theatre, most professional houses have a small complement of lighting and control but do not provide the quantity or choice of equipment for a large production. This dictates that the production company rents the additional lighting control and dimming required. The advantages are that the desired type and make of equipment can be chosen with the cost paid weekly from the takings or at the worst the equipment can be returned in the event of a disaster.

In TV the main requirement is for outside broadcast lighting, and on occasion to supplement the normal studio lighting with special units used for effects lighting.

While the rental system is most helpful and seems to fill a very real need it should not be entered into lightly, without reading the small print, usually found on the back of acceptance delivery notes and contracts issued at the time of ordering. Each rental company has its own conditions. The following are some of the more important ones found by the authors.

The customer hiring the equipment must check and test it before it is used and satisfy himself as to its fitness for the purpose. Further the customer must have adequate insurance cover to protect the rental company from claims against it for its products or personnel employed by the rental company for legal actions, proceedings, costs, charges, expenses and indemnity of third parties. The equipment must only be operated by people with the appropriate qualifications. If the customer uses labour provided by the rental company, the customer is responsible for them whilst on site, including any damages done, expenses or consequential indirect loss.

Finally, many an expensive argument can be avoided by determining if the cost of the hired lighting equipment also includes the lamps.