Weston Park Museum
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Specification for Showcase Lighting

This is a specification that was produced for a specific project using various case sizes with internal fibre-optic lighting. However much of the specification can be used for other internal lighting system. For instance other types of light boxes still need safe access and through ventilation. Please feel free to copy, adapt and use the specification on your own jobs. Note that it is for you to determine if the specification meets your own project’s needs and we cannot be held responsible for any subsequent actions or results from using this specification. Contact us if you need specific advice on its use, adaptation or applicability.

Please let us know if there are points you would like to make about it or feedback from suppliers that may be useful to us or to others that use the specification in the future.

General specification for cases with fibre-optic lighting

Case lighting

A dimmable fibre-optic system shall be provided for each case. This may consist of a single projector and harness or more than one projector and harness – see case schedule for requirements.

For all cases the projector lamp size and tail sizes shall be chosen and supplied such that the lighting level shown on the case schedule can be achieved on the front surfaces of all objects and label panels in the case (default value 200 Lux). See designer’s drawings or description for intended object type/layout.

The lengths of the fibre-optic tails shall be sized such that the projector can be placed in a readily accessible location for re-lamping and adjustment. (see ‘Projectors’ below)

Fibre-optic harness

The fibres in all harnesses shall be fully randomised at the common-end to ensure even light distribution over all tails.

Unless noted otherwise in the case schedule or on drawings, the fibre-optic tails are to pass through seals to maintain a dust-proof and airtight seal between the case interior and the outside or light box environment.

Optics

The lenses on the adjustable optics shall be of the screw-on type such that they can be readily interchanged between optics and be screwed in or out to give some fine control of beam angle.

For each run of optics along a row, wide angle and narrow angle lenses shall alternate along the run.

In all cases adjustable optics shall be accessible within the case for aiming and adjustment. The optics shall be adjustable to at least 35° from the central position in any direction.

The optics shall be free enough to be readily adjustable by hand from within the finished case, but held firmly enough to stay in position once aimed.

Unless noted otherwise on the case schedules or drawings the optics shall be contained in a recessed trough so that the optics are not immediately visible from outside the case. The optics shall be mounted in one sloping face of the trough facing into the body of the case. For troughs at the top of the case the optics must be able to be adjusted to face straight down the glass case front to ensure labels and objects close to the glass can be well lit. Similarly for side-mounted optics these should be able to light straight across the face of the case to light the fronts of objects close to the glass.

The trough shall be mounted directly behind the support for the front glass of the case to give good lighting angles onto the objects within the case. See typical example detail below.

Projectors

Except where noted in the case schedule or on drawings the projectors are to be housed in the top compartment of the case unless agreed otherwise. Ventilation panels or louvers shall be provided in the top of this compartment that allows free movement of air whist preventing light leakage. Removable or hinged access panels on this compartment shall give clear access to the projectors for re-lamping or maintenance. To ensure safety any upward opening hinged lids are to have integral props to hold the lid safely in the open position.

If the projector is housed in a compartment below the object section of the case through ventilation is to be provided i.e. low-level cool air in and high-level hot air out. This is to avoid excessive heat build up that may affect the objects in the case and also lead to a shorter life of the projector’s lamp.

Metal-halide projectors shall have local hand operated mechanical dimming. I.e. a directly operated rotary perforated plate, not remote motor driven perforated plate unless the control for it is agreed in advance of installation.

Tungsten-halogen projectors shall have locally controlled high-frequency dimming provided. The control for it is to be provided in a readily accessible location adjacent to each projector or separately adjacent to the case if this if this is agreed in advance or is shown on the drawings or detailed in the case schedule.

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