If possible the lamp and camera should always be installed where they cannot be touched by passes-by, otherwise it is not a secure system, or that passers by cannot stare at the lamp closer than the Minimum Safe Working Distance (MSWD) in Table 1. The MSWD refers to the central part of the beam which is the most intense, and under conditions of continuous viewing for up to 8 hours.

Taking the most prudent and cautious approach fig.2 shows that even an exceptionally tall person whose eyes are 2m (6ft.6ins.) above ground would have to come within 3m (4ft.3ins) of the mounting post of a lamp mounted 3m (9ft.10ins) above ground before entering the hazard zone of a 500 spot. Even in the unlikely event that at the closest distance of 1m (3ft.3ins) and with the lamp shining directly downwards the observer staring upwards into the lamp for up to 3 minutes is within the safety limits.

As a rule of thumb if you can feel the heat, don't stare or touch the lamp.

The Derwent range of LED illuminators have a narrow band output and can be viewed continuously at even shorter distances with a MSWD of 0.3m (12ins.)

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