Security lighting

Security lighting to prevent intrusions may be counter-productive. Turning off lights halved the number of thefts and burglary in Övertorneå Sweden. ^[2][3] 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.^[4]

In the early seventies, the public-school system in San Antonio, Texas, began leaving many of its school buildings, parking lots, and other property dark at night and found that the no-lights policy not only reduced energy costs but also dramatically cut vandalism.^[5]

Bright, unshielded floodlights often prevent people from noticing criminal activity, and help criminals see what they are doing.^[6]

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:

• 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 nadir. Lighting should be bright enough, and not "as bright as possible". In many cases a good rule of thumb is 0.5 watts per square metre (0.05 watts per square foot). This might need to be increased in complex 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.
• Prevent malicious tampering or interference. This means that besides the lamp itself, the entire circuit from the source (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 conduits 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.

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Övertorneå

Övertorneå

Övertorneå is a locality and the seat of Övertorneå Municipality in Norrbotten County, Sweden with 1,917 inhabitants in 2010.

Closed-circuit television

Closed-circuit television

Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point-to-point (P2P), point-to-multipoint (P2MP), or mesh wired or wireless links. Even though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that require additional security or ongoing monitoring.

Vandalism

Vandalism

Vandalism is the action involving deliberate destruction of or damage to public or private property.

Wire

Wire

A wire is a flexible strand of metal.

Mesh

Mesh

A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands.

Polycarbonate

Polycarbonate

Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily worked, molded, and thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique resin identification code (RIC) and are identified as "Other", 7 on the RIC list. Products made from polycarbonate can contain the precursor monomer bisphenol A (BPA).

Mirror

Mirror

A mirror or looking glass is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminium are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very hard surface.

Emergency power system

Emergency power system

An emergency power system is an independent source of electrical power that supports important electrical systems on loss of normal power supply. A standby power system may include a standby generator, batteries and other apparatus. Emergency power systems are installed to protect life and property from the consequences of loss of primary electric power supply. It is a type of continual power system.

Nadir

Nadir

The 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.

Rule of thumb

Rule of thumb

In English, the phrase rule of thumb refers to an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the 17th century and has been associated with various trades where quantities were measured by comparison to the width or length of a thumb.

Watt

Watt

The watt is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution.

Electrical conduit

Electrical conduit

An electrical conduit is a tube used to protect and route electrical wiring in a building or structure. Electrical conduit may be made of metal, plastic, fiber, or fired clay. Most conduit is rigid, but flexible conduit is used for some purposes.

A sodium vapor light. This type is often used as security lighting.

Security lighting can be used in residential, commercial, industrial, institutional, and military settings. Some examples of security lighting include floodlights and low pressure sodium vapour lights. Most lights intended to be left on all night are high-intensity discharge lamps 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.

LED-based security lighting is becoming increasingly popular, due to its low electrical consumption (compared to non-LED lighting technologies), long lifespan, and options for different color spectrum ranges.^[7]

Other lights may be activated by sensors such as passive infrared sensors (PIRs), turning on only when a person (or other mammal) approaches. 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.

To reduce light pollution, the International Dark-Sky Association recommends the use of downward-facing security lights that preserve and protect the night time environment.

During the South African energy crisis increased rates of metal theft, house breaking and robberies were reported in areas effected by the loss of security lighting due to a loss of electricity in some urban areas.

^{[8][9][10][11][12]}

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High-intensity discharge lamp

High-intensity discharge lamp

High-intensity discharge lamps are a type of electrical gas-discharge 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 noble gas and often also contains suitable metal or metal salts. The noble gas enables the arc's initial strike. Once the arc is started, it heats and evaporates the metallic admixture. Its presence in the arc plasma greatly increases the intensity of visible light produced by the arc for a given power input, as the metals have many emission spectral lines in the visible part of the spectrum. High-intensity discharge lamps are a type of arc lamp.

Passive infrared sensor

Passive infrared sensor

A passive infrared sensor is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications.

International Dark-Sky Association

International Dark-Sky Association

The International Dark-Sky Association (IDA) is a United States-based non-profit organization incorporated in 1988 by founders David Crawford, a professional astronomer, and Tim Hunter, a physician and amateur astronomer. The mission of the IDA is "to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting."

South African energy crisis

South African energy crisis

The South African energy crisis is an ongoing period of widespread national blackouts of electricity supply. It began in the later months of 2007 and continues to the present. The South African government-owned national power utility and primary power generator, Eskom, and various parliamentarians attributed these rolling-blackouts to insufficient generation capacity.

Metal theft

Metal theft

Metal theft is "the theft of items for the value of their constituent metals". It usually increases when worldwide prices for scrap metal rise, as has happened dramatically due to rapid industrialization in India and China. Apart from precious metals like gold and silver, the metals most commonly stolen are non-ferrous metals such as copper, aluminium, brass, and bronze. However, even cast iron and steel are seeing higher rates of theft due to increased scrap metal prices.

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 burglaries occur during the day,^[2][13][14] 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. Non-uniform illumination may also interfere with surveillance systems, as the wide dynamic range of security cameras may have difficulty adjusting to the changes in light intensity.