As Rainbow CCTV introduces its new line of infrared illuminators, we are making every effort to educate CCTV users of the safe installation and operation of infrared illuminators.

In Great Britain, there are now over 200,000 infrared illuminators of various types in use, allowing safe and effective night time CCTV. As a leading provider of infrared illumination systems for CCTV, Rainbow has an obligation to ensure its customers are given the knowledge to safely install and use their products. Rainbow takes this obligation very seriously and based on up to date information, customers that follow the guidelines laid out by the manufacturer can have confidence that their security system is installed and used in a safe manner.

Rainbow CCTV is not aware of any reported case of eye damage from the radiation from quartz/halogen or LED IR lamps used in CCTV.

Rainbow’s UF500 lamps are designed to allow operation at safety levels that exceeds the guideline safety standards of the American Conference of Government Industrial Hygienists (ACGIH).

Background:

Throughout history people have been exposed to high levels of infrared radiation, in the making of steel or glass, simply being out in strong sunlight, in fact anywhere close to a hot object. Infrared gives a heating effect, which we sometimes use to keep us warm, but too much on the skin can cause blistering. Industry is aware of the dangers of high intensity IR radiation and the risks and effects of over-exposure to it are well known.

Bright natural light which contains infrared causes the eye to blink, the iris to contract and the viewer to look away. These normal defense mechanisms do not happen when the visible part of the light has been removed. The eyes are more sensitive than the skin, and over-exposure for long periods may give rise to retinal damage and cataracts. These are the hazards of over-exposure to IR.

Other sources of IR are lasers, which give high intensity beams. These intense beams have necessitated safety regulations. These regulations encompass conventional light sources. Rainbow has reviewed these regulations ^1,2,3 and have produced the following guidelines for the use of our products.

There are two scenarios which have to be considered with these security systems, safety in use which is long term and safety during installation, testing and maintenance which is shorter term. Details of the technical aspects which were used to arrive at these recommended safe working limits are given later.

Safety in Use

The infrared lamp should always be installed where it cannot be touched by passers-by, and positioned so that passers-by cannot stare at the lamp from closer than the Safe Working Distance (SWD) in Table 1. The SWD refers to the central part of the beam which is the most intense, and under conditions of continuous viewing for up to 8 hours.

In the worst case scenario, even an exceptionally tall person whose eyes are 6ft. 6ins. (2m.) above ground would have to come within 4ft. 3in. (1.3m.) of the mounting post of a lamp mounted 9ft. 10ins. (3m.) above ground before entering the hazard zone of a UF500 spot lamp. Even in the unlikely event that at the closest distance of 3ft.3ins. (1m.) 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 at the lamp.

Table 1 - Rainbow Products - Safe Working Limits

Safe Working Distances for up to 8 hours Viewing

Although the ACGIH guidelines can be interpreted to suggest the Rainbow lamps can be safely viewed at very close distances, Rainbow discourages direct viewing at any distance below the SWD. If the lamp is on, the heat from it can be felt by passing a hand in front of the lens. A second observer at a distance greater than SWD should be used to check that the lamp is functioning and that the filter is acceptable for either overt or covert operation. During final adjustments a monitor linked to the camera is recommended, as described in the installation instructions supplied with the lamp. For regular maintenance at the camera head, the lamp should be turned off. Multiple lamp systems have designed configurations so that overlapping intensities do not exceed the center beam intensity of a single lamp at the SWDs.

The ACGIH publish the TLV (Threshold Limit Values) for various physical agents; they recommend a TLV of 10 mWcm.^-2 for the irradiance of near infrared radiation under conditions of viewing for longer than 16mins. For shorter durations (less than 1000 sec.) the following formula can be used⁴.

Sumation(I_l D_l) from F1 to 1400 <1.8t^0.75 Wcm^-2

D_l is the spectral range of the lamp output, t is viewing time in seconds, F1 is the filter cut-off wavelength. If the center beam irradiance of the lamp is measured at a known distance, then the above criteria and the inverse square law

I₁r1₂=I₂r2₂

(where I₁ and I₂ are the irradiances at distances r₁ and r₂ respectively), are used to find the Safe Working Distance from the lamp.

Rainbow lamps have a center beam irradiance of 10 mWcm^-2 at the SWDs which is the minimum recommended viewing distance under normal conditions.

Disclaimer: Rainbow CCTV makes every effort to test its products and provide safety information regarding installation and usage. However, responsibility for safety ultimately rests with those installing and using this equipment. Rainbow CCTV/ISO does not assume responsibility for accidents or injuries occurring during the use of our products.

1. American National Standards Institute (ANSI) Z136-1-1993.
2. American Conference of Government Industrial Hygienists (ACGIH) 'Threshold Limits Values' 1994.
3. European Standard EN 60825-1 1994-1996.
4. Institute of Electrical and Electronic Engineers (IEEE) 0-7803-2627-X/95 1995 by H. Devereux and M. Smalley