CCTV
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Internet CCTV GUIDE - Housings
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There are four groups of housings classified according to environmental conditions in which they should properly work, ensuring desired level of protection:
There are four groups of housings classified according to environmental conditions in which they should properly work, ensuring desired level of protection:
- Environment class I (indoor) - closed rooms, temp. 5 to 40
- Environment class II (indoor, general) - closed rooms not heated continuously, temp. -10 to 40
- Environment class III (outdoor shaded places) - outer conditions not fully depending on weather conditions, temp. -25 to 500 C, humidity to 85 - 95%,
- Environment class IV (outdoor, general) - temp. -25 to 600 C, humidity to 85 - 95%,
PN-EN-50130-5 (Alarm systems - Environmental tests.)
In order to ensure proper work conditions for protected devices, depending on specific environment, housings may be equipped with heaters, fans, cooling systems etc.
In CCTV systems, the most vulnerable to environmental conditions items are cameras. Most of them can work in temperature range from -10 to 50 0 and humidity of air reaching 90% (without water contact). If these requirements are not fulfilled, we should use special housings that will ensure, the suggested by a manufacturer, work conditions of the camera and lens. It is highly important for proper camera work to keep such conditions that won't allow to mist over the surface of lens (dew point) - to secure it heaters with thermostat are used. To ensure steady temperature in more expensive models, fans are also additionally installed inside the housing.
Housings may have information about compliance with IP norm They should furthermore secure good vandal resistance, easy access to camera, lens, etc. for maintenance purposes. They should ensure optimal work conditions taking into account temperature increase inside housing caused by heat generated by the device itself. Housings may have information about conformity with IP norm. This norm tells about resistance against penetration of solid objects (the first number) and against liquids (the second number). Camera housings usually have conformity with norms IP 65 or IP66, what means that are fully dust resistant and partially secured against water penetration. In the case of work in high humidity environment we should use cameras marked with IP67 or IP68; the second ones can work under water.
Classification of housings according to IP ratings. Additional information can be found in the 1976 IEC Publication: Classification of Degrees of Protection Provided by Enclosures.
IP Rating | The first number | The second number | |
| Protection of people against touching parts that are moving or being under voltage | Degree of protection against penetration of solid objects into the housing | Degree of protection against penetration of liquids into the housing | |
| 0 | No protection | No protection | No protection |
| 1 | Protection against accidental contact by hand, but not deliberate contact | Protection against large objects of diameter 50 mm and bigger | Protection against drops of condensed water. |
| 2 | Protection against contact by fingers | Protection against medium-size objects of diameter 12 mm and bigger | Protection against vertically falling raindrops on devices 15° tilted from vertical |
| 3 | Protection against contact by tools, wire, etc of diameter 2.5 mm and bigger | Protection against small foreign objects of diameter 2.5 mm and bigger | Protection against rain. No harmful effect from rain at angle less than 60° from vertical |
| 4 | As above, but diameter 1 mm and bigger | As above, but diameter 1 mm and bigger | Protection against splashing from any direction |
| 5 | Complete protection against contact with live or moving parts | Protection against harmful deposits of dust | Protection against water jets from any direction |
| 6 | As above | Full protection against penetration of dust | Protection against conditions on ships' decks. Water from heavy seas will not enter |
| 7 | – | – | Protection against immersion in water. Water will not enter under stated conditions of pressure and time |
| 8 | – | – | Protection against indefinite immersion in water under a specified pressure |
According to temperature maintenance, housings can be divided into several groups:
- Equipped with heater and thermostat; the heater is usually mounted in the front of housing, on the bottom by glass window. Its main job, besides maintenance of adequate temperature, is protection against freezing and condensation of water (especially on lens surface, what would cause significant distortion of image),
- Air-cooled housings with natural convection ventilation, used in places with low temperature differences, e.g. shaded rooms. In other cases, due to overheating possibility, air-cooled housings with forced ventilation and heater are employed, e.g. cameras on south side of a building,
- Air-cooled housings with forced circulation and compressor; they are required in localizations with high temperature differences, e.g. observation of technological processes,
- Water-cooled housings working in extremely very high temperatures e.g. in steelworks.
- Equipped with heater and thermostat; the heater is usually mounted in the front of housing, on the bottom by glass window. Its main job, besides maintenance of adequate temperature, is protection against freezing and condensation of water (especially on lens surface, what would cause significant distortion of image)
- Air-cooled housings with natural convection ventilation, used in places with low temperature differences, e.g. shaded rooms. In other cases, due to overheating possibility, air-cooled housings with forced ventilation and heater are employed, e.g. cameras on south side of a building===
- Air-cooled housings with forced circulation and compressor; they are required in localizations with high temperature differences, e.g. observation of technological processes
- Water-cooled housings working in extremely very high temperatures e.g. in steelworks.
It is worth to note that mounting a camera in small housing may allow to keep sufficiently stable temperature even without additional heater, due to the heat generated by the camera itself. In turn, a camera in hermetic housing (i.e. adapted for work in very dusty or humid rooms) may even without a heater reach temperature higher than allowed; in this case use of cooling measures is essential. The most important role of a heater and thermostat is ensuring right and stable temperature - elimination of step changes of work conditions of camera and lens. Protection against freezing and condensation of water is one of the basic requirements for any CCTV system.
Housing heater M5614
Special housings.
In flammable environment we should definitely use special housings adapted to work in zones at risk of explosion; they are expensive, but they ensure adequate security level. Prices of these housings may exceed a few hundred times camera prices. They simply must fulfill strict security norms.
In flammable environment we should definitely use special housings adapted to work in zones at risk of explosion; they are expensive, but they ensure adequate security level. Prices of these housings may exceed a few hundred times camera prices. They simply must fulfill strict security norms.
Explosion-proof housing of Videotec company.
Keeping housing glass from getting dirty may require to use a wiper and washer. In some cases such special housings, e.g. with wipers, are employed for cameras mounted very high (e.g. on poles), where any access would be very troublesome, or when images from a camera must definitely be available even during variable atmospheric conditions - rain or snow.
There are also housings designated to use in the risk of vandalism; they are made of transparent polycarbonates and durable alloys. Usually they have dome form adapted for attaching to a ceiling or boom.
Housing sizes.
Camera housings have various sizes. The smallest i.e. M5430, M5434 are designated to encapsulate camera modules with PCB size around 32x32mm placed inside. This housings don't have heater - the heat generated by working camera allows to keep temperature stable enough for operation in their typical applications. We should be aware of possible distortion of images in the case of high differences or quick changes of temperature, due to possibility of misting over. Important part of installation work is proper sealing of the hole made for taking out wires (improper sealing is the commonest reason of bad work or damage).
Camera housings have various sizes. The smallest i.e. M5430, M5434 are designated to encapsulate camera modules with PCB size around 32x32mm placed inside. This housings don't have heater - the heat generated by working camera allows to keep temperature stable enough for operation in their typical applications. We should be aware of possible distortion of images in the case of high differences or quick changes of temperature, due to possibility of misting over. Important part of installation work is proper sealing of the hole made for taking out wires (improper sealing is the commonest reason of bad work or damage).
Significantly bigger housings are designated for normal size CCTV cameras requiring also to choose suitable lenses. These housings are equipped with heaters powered by AC 230V e.g. M5415, M5414 or or with DC12V heaters M5405. There are also available models without heaters e.g. M5402. A heater can be bought separately e.g. M5614.
Ease of assembling.
Another issue, beside camera housing size, on which we should pay attention during its selection, is ease of assemblage and durability. Seemingly unimportant matter, however during installation of a large number of cameras such solutions as:
Another issue, beside camera housing size, on which we should pay attention during its selection, is ease of assemblage and durability. Seemingly unimportant matter, however during installation of a large number of cameras such solutions as:
Ease of assembling.Another issue, beside camera housing size, on which we should pay attention during its selection, is ease of assemblage and durability. Seemingly unimportant matter, however during installation of a large number of cameras such solutions as:
- Way of opening: "turning aside" or "upwards" - considerably making easier to set lens sharpness, assembling of additional elements, wires;
- Adequate housing security - use of screws requiring special key;
- Availability of a large number of brackets that allow installing the housing not only on walls but also on ceilings, on poles etc,
Significantly help to shorten installation time and make camera's installation optimal. There are also used housings designated for concrete applications, e.g. underwater. Most of manufacturers offer full sets: camera with lens, housing, wires (optionally with IR lamp). Installers needn't worry about tightness of bushings then.
Camera in vandal proof housing M10908
We should always remember to leave enough free space inside camera's housing for cables and additional devices as heaters, devices securing video line, power supplies or modulators. In the case of using twisted-pair cables (or other special cables) as transmission carrier, adequate transmitting devices are also installed in housings.
During installation of a camera it is important to remember about separation the zero voltage supply rail of the camera and analogical rail or chassis of the housing.
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