Security lighting
Encyclopedia
In the field of physical security
, security lighting is often used as a preventative and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases simply to increase the feeling of safety. Lighting is integral to crime prevention through environmental design
.
Sweden.
A test in West Sussex UK showed that adding all-night lighting in some areas made people there feel safer, although crime rates increased 55% in those areas compared to control areas and to the county as a whole.
Bright, unshielded floodlights often prevent people from noticing criminal activity, and help criminals see what they are doing.
While adequate lighting around a physical structure is deployed to reduce the risk of an intrusion, it is critical that the lighting be designed carefully as poorly arranged lighting can create glare which actually obstructs vision.
Studies have shown that many criminals are aware of this effect and actively exploit it.
The optimal design will also depend on whether the area will be watched directly by humans or by closed-circuit television
, and on the location of the observers or cameras.
Security lighting may be subject to vandalism
, possibly to reduce its effectiveness for a subsequent intrusion attempt. Thus security lights should either be mounted very high, or else protected by wire
mesh
or tough polycarbonate
shields. Other lamps may be completely recessed from view and access, with the light directed out through a light pipe or reflected from a polished aluminium or stainless steel mirror
. For similar reasons high security installations may provide a stand-by power supply
for their security lighting.
Some typical considerations include:
Security lighting can be used in residential, commercial, industrial, institutional, and military settings. Some examples of security lighting include floodlight
s and low pressure sodium vapour light
s. Most lights intended to be left on all night are high-intensity discharge lamp
s as these have good energy efficiency, thus reducing the cost of running a lamp for such long periods.
A disadvantage of low pressure sodium lamps is that the colour is pure yellow, so the illuminated scene is seen without any colour differentiation. Consequently high pressure sodium vapour lamps (which are still yellowish, but closer to golden white) are also used, at the cost of greater running expenses and increased light pollution. High pressure sodium lamps also take slightly longer to restrike after a power interruption.
Other lights may be activated by sensors such as passive infrared sensors (PIRs), turning on only when a person (or other mammal) approaches. PIR activated lamps will usually be incandescent bulbs so that they can activate instantly; energy saving is less important since they will not be on all the time. PIR sensor activation can increase both the deterrent effect (since the intruder knows that he has been detected) and the detection effect (since a person will be attracted to the sudden increase in light). Some PIR units can be set up to sound a chime as well as turn on the light. Most modern units have a photocell so that they only turn on when it is dark.
s), used to illuminate areas which have been used by drug addicts to inject drugs. The idea is that the blue lighting makes it impossible to identify veins, thus discouraging the addicts from using that location to "shoot up" and then discard needles.
occur during the day, when the occupants are away at work or shopping.
As with any lighting, security lighting can reduce night vision
, making it harder to see into areas that are unlit or are in shadow.
Physical security
Physical security describes measures that are designed to deny access to unauthorized personnel from physically accessing a building, facility, resource, or stored information; and guidance on how to design structures to resist potentially hostile acts...
, security lighting is often used as a preventative and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases simply to increase the feeling of safety. Lighting is integral to crime prevention through environmental design
Crime prevention through environmental design
Crime prevention through environmental design is a multi-disciplinary approach to deterring criminal behavior through environmental design. CPTED strategies rely upon the ability to influence offender decisions that precede criminal acts...
.
Planning considerations
Some people are surprised to learn that security lighting can be counter-productive. Turning off lights halved the number of thefts and burglary in ÖvertorneåÖvertorneå
Övertorneå is a locality and the seat of Övertorneå Municipality in Norrbotten County, Sweden with 1,965 inhabitants in 2005.It is located at the shore of the Torne River, opposite to Ylitornio...
Sweden.
A test in West Sussex UK showed that adding all-night lighting in some areas made people there feel safer, although crime rates increased 55% in those areas compared to control areas and to the county as a whole.
Bright, unshielded floodlights often prevent people from noticing criminal activity, and help criminals see what they are doing.
While adequate lighting around a physical structure is deployed to reduce the risk of an intrusion, it is critical that the lighting be designed carefully as poorly arranged lighting can create glare which actually obstructs vision.
Studies have shown that many criminals are aware of this effect and actively exploit it.
The optimal design will also depend on whether the area will be watched directly by humans or by closed-circuit television
Closed-circuit television
Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....
, and on the location of the observers or cameras.
Security lighting may be subject to vandalism
Vandalism
Vandalism is the behaviour attributed originally to the Vandals, by the Romans, in respect of culture: ruthless destruction or spoiling of anything beautiful or venerable...
, possibly to reduce its effectiveness for a subsequent intrusion attempt. Thus security lights should either be mounted very high, or else protected by wire
Wire
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
mesh
Mesh
Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands.-Types of mesh:...
or tough polycarbonate
Polycarbonate
PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
shields. Other lamps may be completely recessed from view and access, with the light directed out through a light pipe or reflected from a polished aluminium or stainless steel mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...
. For similar reasons high security installations may provide a stand-by power supply
Emergency power system
Emergency power systems are a type of system, which may include lighting, generators, fuel cells and other apparatus, to provide backup power resources in a crisis or when regular systems fail. They find uses in a wide variety of settings from residential homes to hospitals, scientific...
for their security lighting.
Some typical considerations include:
- Reduce and prevent glare and situations mentioned above
- Shielded or full cut-off (FCO) lamp housings which conceal the bulb could be used, which should direct light onto the ground or target and away from observers. These lights should send no light above 80 degrees from the nadirNadirThe nadir is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous...
. Lighting should be bright enough, and not "as bright as possible". In many cases a good rule of thumbRule of thumbA rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...
is 0.5 wattWattThe watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s per square metre (0.05 watts per square foot). This might need to be increased in very confused environments, but conversely can be reduced in very open environments. Multiple lamps of moderate power instead of a few powerful lamps will reduce glare, provide more even illumination with reduced pools of shadow, and provide some redundancy if one lamp's bulb blows out or develops a bad ballast.
- Shielded or full cut-off (FCO) lamp housings which conceal the bulb could be used, which should direct light onto the ground or target and away from observers. These lights should send no light above 80 degrees from the nadir
- Prevent malicious tampering or interference. This means that besides the lamp itself, the entire circuit from the source (Electric companyElectric companyElectric company can mean:*Electrical power industry*Electric Company *The Electric Company *The Electric Company...
or generator), through the wires, to the lamp and back should be protected.- Luminaires should be accessible so that the maintainer can replace blown bulbs as quickly as possible and clean the luminaires periodically. However they should be protected or somehow made inaccessible to tampering.
- Ensure the electric meter box is locked or inaccessible, or else power the lights from a different line.
- Control and power lines, where outside or vulnerable, should be either buried well underground (in conduitElectrical conduitAn electrical conduit is an electrical piping system used for protection and routing of electrical wiring. Electrical conduit may be made of metal, plastic, fiber, or fired clay. Flexible conduit is available for special purposes....
s preferably) or at a height of at least 8 metres (about 24 feet). - Ideally multiple circuits should be used to prevent an accidental or malicious short or cut causing all illumination to fail.
Use
High-intensity discharge lamp
High-intensity discharge lamps are a type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with both gas and metal salts. The gas facilitates the...
s and low pressure sodium vapour light
Sodium vapor lamp
A sodium vapor lamp is a gas discharge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high pressure...
s. Most lights intended to be left on all night are high-intensity discharge lamp
High-intensity discharge lamp
High-intensity discharge lamps are a type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with both gas and metal salts. The gas facilitates the...
s as these have good energy efficiency, thus reducing the cost of running a lamp for such long periods.
A disadvantage of low pressure sodium lamps is that the colour is pure yellow, so the illuminated scene is seen without any colour differentiation. Consequently high pressure sodium vapour lamps (which are still yellowish, but closer to golden white) are also used, at the cost of greater running expenses and increased light pollution. High pressure sodium lamps also take slightly longer to restrike after a power interruption.
Other lights may be activated by sensors such as passive infrared sensors (PIRs), turning on only when a person (or other mammal) approaches. PIR activated lamps will usually be incandescent bulbs so that they can activate instantly; energy saving is less important since they will not be on all the time. PIR sensor activation can increase both the deterrent effect (since the intruder knows that he has been detected) and the detection effect (since a person will be attracted to the sudden increase in light). Some PIR units can be set up to sound a chime as well as turn on the light. Most modern units have a photocell so that they only turn on when it is dark.
Blue lighting
A recent addition to the field of security lighting is the blue outdoor lamp (similar to mercury-vapor lampMercury-vapor lamp
A mercury-vapor lamp is a gas discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb...
s), used to illuminate areas which have been used by drug addicts to inject drugs. The idea is that the blue lighting makes it impossible to identify veins, thus discouraging the addicts from using that location to "shoot up" and then discard needles.
Limitations
An important limitation to the usefulness of security lighting is the simple fact that it is only useful at night. This is particularly significant for home owners because, contrary to a widespread myth, most household burglariesBurglary
Burglary is a crime, the essence of which is illicit entry into a building for the purposes of committing an offense. Usually that offense will be theft, but most jurisdictions specify others which fall within the ambit of burglary...
occur during the day, when the occupants are away at work or shopping.
As with any lighting, security lighting can reduce night vision
Night vision
Night vision is the ability to see in low light conditions. Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range...
, making it harder to see into areas that are unlit or are in shadow.
See also
- Access controlAccess controlAccess control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...
- Environmental designEnvironmental designEnvironmental design is the process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products...
- Light pollutionLight pollutionLight pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
- Physical SecurityPhysical securityPhysical security describes measures that are designed to deny access to unauthorized personnel from physically accessing a building, facility, resource, or stored information; and guidance on how to design structures to resist potentially hostile acts...
- SecuritySecuritySecurity is the degree of protection against danger, damage, loss, and crime. Security as a form of protection are structures and processes that provide or improve security as a condition. The Institute for Security and Open Methodologies in the OSSTMM 3 defines security as "a form of protection...
- Security engineeringSecurity engineeringSecurity engineering is a specialized field of engineering that focuses on the security aspects in the design of systems that need to be able to deal robustly with possible sources of disruption, ranging from natural disasters to malicious acts...