 International safety symbol "Caution, risk of electric shock" ( ISO 3864), colloquially known as high voltage symbol. The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements. High voltage is used in electrical power distribution, in cathode-ray tubes, to generate X-rays and particle beams, to demonstrate arcing, for ignition, and in photomultiplier tubes. Image File history File links High_voltage_warning. ...
Image File history File links High_voltage_warning. ...
Logo of the International Organization for Standardization The International Organization for Standardization, also known as ISO, is an international standard-setting body composed of representatives from national standards bodies. ...
Electricity distribution is the penultimate process in the delivery of electric power, the part between transmission and user purchase from an electricity retailer. ...
The cathode ray tube or CRT, invented by Karl Ferdinand Braun, is the display device used in most computer displays, video monitors, televisions and oscilloscopes. ...
In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...
In order to create a particle beam one must have a section called an ion source in which the beam is created by exciting electrons. ...
An electric arc can melt calcium oxide. ...
Ignition occurs when the heat produced by a reaction becomes sufficient to sustain the reaction, whether it be a fire, an explosion, or nuclear fusion. ...
Photomultipliers, or photomultiplier tubes (PMT) are extremely sensitive detectors of light in the ultraviolet, visible and near infrared. ...
The International Electrotechnical Commission and its national counterparts (IEE, IEEE, VDE, etc.) define high voltage circuits as those with at least 1000 V for alternating current and at least 1500 V for direct current, and distinguish it from low voltage (50–1000 V AC or 120–1500 V DC) and extra low voltage (<50 V AC or <120 V DC) circuits. The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ...
Not to be confused with the Institute of Electrical and Electronics Engineers. ...
The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...
VDE stands for Virtual Directory Engine, and is synonymous to Virtual Directory. ...
Josephson junction array chip developed by NIST as a standard volt. ...
City lights viewed in a motion blurred exposure. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
The use of extra low voltage (ELV) in an electrical circuit is one of several means to provide protection against electrical shock. ...
Other definitions exist as well. For example, in the United States 2005 National Electrical Code (NEC), high voltage is any voltage over 600 V (article 490.2). Laypersons may consider household mains circuits (100–250 V AC), which carry the highest and most dangerous voltages they normally encounter, to be high voltage. In digital electronics, a high voltage is the one that represents a logic 1 (1.1–5 V). The National Electrical Code is Part 70 of a set of codes and standards set forth by the National Fire Protection Association (NFPA). ...
Type F Mains power plug & socket The term mains usually refers to the general purpose AC electrical power supply (as in Ive connected the appliance to the mains). The term is not usually used in the United States and Canada. ...
Digital Electronics is based on a number of discrete voltage levels, usually two, as distinct from analog electronics which uses voltages to represent variables directly. ...
Safety and insurance industry
Whilst mains voltages are capable of delivering fatal shocks and may constitute high-voltage hazards, they cannot jump significant distances, so they are dangerous only if touched. Therefore standards bodies do not generally refer to them as high voltages.
Various safety and insurance organizations consider anything outside of the ELV range (i.e. greater than 50 V) to be dangerous and in need of regulation. Voltages above this range are capable of producing heart fibrillation if they produce electric currents in body tissues which happen to pass through the chest area. The electrocution danger is mostly determined by the low conductivity of dry human skin. If skin is wet (especially with electrolytes, including sea water) or if there are wounds, or if the voltage is applied to electrodes which penetrate through the skin, then even voltages far below 40 V can be lethally high. On the other hand, voltages above approximately 500 V have a natural defibrillating effect, so sometimes a higher voltage can be safer than a lower voltage, though by no means safe. A DC circuit may be especially dangerous because it will cause muscles to lock around the wire. It has also been noted that accidental contact with high voltage power lines has not always been fatal because sometimes the victim is thrown clear of the power line by the intensity of the arc that is created and has survived, although with extremely severe injuries. Warning signs, such as this one, can improve safety awareness. ...
Insurance, in law and economics, is a form of risk management primarily used to hedge against the risk of potential financial loss. ...
Fibrillation is the rapid, irregular, and unsynchronized contraction of the muscle fibers of the heart. ...
Electric current is the flow of electric charge. ...
Chest of a human male The chest is a part of the anatomy of humans and various other animals. ...
The term electrocution can mean either: death by electric shock, usually by accident or deliberate execution by electric shock, in an electric chair See also: Capital punishment (death penalty) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
Electrical conductivity is a measure of how well a material accommodates the transport of electric charge. ...
An electrolyte is a substance that dissociates into free ions when dissolved (or molten), to produce an electrically conductive medium. ...
An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e. ...
A semi-automatic external defibrillator (AED) A defibrillator is a medical device used in the defibrillation of the heart. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
Sparks in air The dielectric breakdown strength of dry air at typical room temperature and sea-level pressure is about 24 kV/in (9.6 kV/cm). [1] This value should be taken as a rough guide because the actual breakdown voltage is highly dependent upon the electrode shape and size. High voltages, i.e. strong electric fields produce violet-colored corona discharge in air, as well as visible sparks. Voltages below about 500-700 volts cannot produce easily visible sparks or glows in air at atmospheric pressure, so by this rule these voltages are 'low.' However, under conditions of low atmospheric pressure (such as in high-altitude aircraft), or in an environment of noble gas such as argon, neon, etc., sparks appear at much lower voltages. Five hundred to 700 volts is not a fixed minimum for producing spark breakdown, but it is a rule of thumb. For air at STP, the minimum sparkover voltage is around 380 volts. The term electrical breakdown has several similar but distinctly different meanings. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in situations where sparking (also known as arcing) is not favoured. ...
Look up Spark in Wiktionary, the free dictionary The word spark has several meanings: Sparks produced by grinding In electricity, spark usually refers to a momentary electrostatic discharge across a spark gap. ...
Airbus A380 An aircraft is any machine capable of atmospheric flight. ...
The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. ...
General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ...
General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ...
Extra low voltage circuits can produce large sparks or arcs when a previous flowing current is suddenly interrupted, especially when there is significant inductance present in the circuit. Small sparks, caused by exploding metal surfaces, can occur with significantly smaller voltages; try tapping the terminals of a 9V battery with a paper clip in a dark room. Electric arc welding is an example of an electric arc sustained by voltages of less than 100 volts, but these low voltage arcs are initiated by contact between the welding rod and work piece. The incandescent metal surfaces at the arc's roots and metal vapor in the arc allow it to persist with a low applied voltage. // Definition Inductance is a measure of the amount of magnetic flux produced for a given electric current. ...
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...
Science classroom devices A high voltage is not necessarily dangerous. Physics demonstration devices such as Van de Graaff generators and Wimshurst machines can produce voltages approaching one million volts, yet at worst they deliver a brief sting. These devices have a limited amount of stored energy, so the current produced is low and usually for a short time.[1] During the discharge, these machines apply high voltage to the body for only a millionth of a second or less. The discharge may involve extremely high power over very short periods, but in order to produce heart fibrillation, an electric power supply must produce a significant current in the heart muscle continuing for many milliseconds, and must deposit a total energy in the range of at least millijoules or higher. Alternatively, it must deliver enough energy to damage tissue through heating. Since the duration of the discharge is brief, it generates far less heat (spread over time) than a mobile phone. Van de Graaff generator A Van de Graaff generator is a electrostatic machine which uses a moving belt to accumulate very high voltages on a hollow metal globe. ...
Wimshurst machine with two Leyden jars. ...
A power supply unit (sometimes abbreviated power supply or PSU) is a device or system that supplies electrical or other types of energy to an output load or group of loads. ...
Mil-li-sec-ond One hundreth of a second ...
Note that Tesla coils are a special case, and touching them is not recommended. Among other issues, they have a tendency to arc to their own bottom-end circuitry, which can introduce powerline frequency (50 Hz or 60 Hz, and capable in any case of depolarizing cells and stopping the heart) currents at lethally high voltages to the body. // A Tesla coil is a category of disruptive discharge coils, named after their inventor, Nikola Tesla. ...
Electrostatic attraction/repulsion The terminals of DC high voltage machines can attract dust, lint, and bits of paper. On an everyday scale, voltages higher than a few thousand volts are required in order to create an electric field with a gradient large enough to produce obvious forces. On the other hand, the forces depend on the distance from the electrodes and the electrode shapes, and at the microscopic scale of MEMS, even a few tens of volts acts like a high voltage. In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
In the above two images, the scalar field is in black and white, black representing higher values, and its corresponding gradient is represented by blue arrows. ...
A mite next to a gear set produced using MEMS. Courtesy Sandia National Laboratories, SUMMiTTM Technologies, www. ...
Power lines  High tension power lines. Transmission lines for electric power always use voltages in excess of 50 volts, so contact with or close approach to the line conductors presents a danger of electrocution. Contact with overhead wires is a frequent cause of injury or death. Metal ladders, farm equipment, boat masts, construction machinery, television antennas, and similar objects are frequently involved in fatal contact with overhead wires. Digging into a buried cable can also be dangerous to workers at the excavation site. Digging equipment (either hand tools or machine driven) that contacts a buried cable may energize piping or the ground in the area, resulting in electrocution of nearby workers. Unauthorized persons climbing on power pylons or electrical apparatus are also frequently the victims of electrocution. At very high transmission voltages even a close approach can be hazardous. Electric power is the amount of work done by an electric current in a unit time. ...
The term electrocution can mean either: death by electric shock, usually by accident or deliberate execution by electric shock, in an electric chair See also: Capital punishment (death penalty) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
For high voltage and extra-high voltage transmission lines, specially trained personnel use so-called "live line" techniques to allow hands-on contact with energized equipment. Since training for such operations is lengthy, and still presents a danger to personnel, only very important transmission lines are the objects of live-line maintenance practices. Outside these specialized situations, one should not assume that being ungrounded allows one to safely touch energized objects; grounding, or arcing to ground, can occur in unexpected ways, and high-frequency currents can cause burns even to an ungrounded person (touching a transmitting antenna is dangerous for this reason, and likewise a high-frequency tesla coil can sustain a spark with only one endpoint). A Yagi-Uda antenna An antenna or aerial is an electronic component designed to transmit or receive radio signals (and other electromagnetic waves). ...
Normally protective equipment on high-voltage transmission lines prevents formation of an arc, or insures it is de-energized within a few score milliseconds. Electrical apparatus designed to interrupt high-voltage circuits is designed to safely direct the arc so that it dissipates without damage.
Arc flash hazard Depending on the short circuit current available at a switchgear line-up, a hazard is presented to maintenance and operating personnel due to the possibility of a high-intensity electric arc. Maximum temperature of an arc can exceed 10,000 kelvins, and the radiant heat, expanding hot air, and vaporized metal and insulation material can cause severe injury to unprotected workers. Such switchgear line-ups and high-energy arc sources are commonly present in electric power utility substations and generating stations, industrial plants and large commercial buildings. In the United States the National Fire Protection Association, has published a guideline standard NFPA 70E for evaluating and calculating arc flash hazard, and provides standards for the protective clothing required for electrical workers exposed to such hazards in the workplace. The maximum prospective short circuit current is the maximum electrical current which can flow in a particular electrical system under short circuit conditions. ...
The term switchgear, commonly used in association with the electric power system, or grid, refers to the combination of electrical disconnects and/or circuit breakers meant to isolate equipment in or near an electrical substation. ...
An electric arc can melt calcium oxide. ...
The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ...
The National Fire Protection Association (NFPA) is a U.S. organization (albeit with some international members) charged with creating and maintaining minimum standards and requirements for fire prevention and suppression activities, training, and equipment, as well as other life-safety codes and standards. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Explosion hazard Even voltages insufficient to break down air can be associated with enough energy to ignite atmospheres containing flammable gases or vapours, or suspended dust. For example, air containing hydrogen gas or natural gas or gasoline vapor can be ignited by sparks produced by electrical apparatus. Examples of industrial facilities with hazardous areas are petrochemical refineries, chemical plants, grain elevators, and some kinds of coal mines. ‹ The template below has been proposed for deletion. ...
Natural gas, commonly referred to as gas, is a gaseous fossil fuel consisting primarily of methane. ...
Gasoline (or petrol) is a petroleum-derived liquid mixture consisting primarily of hydrocarbons, used as fuel in internal combustion engines. ...
Measures taken to prevent such explosions include:
- Intrinsic safety, which is apparatus designed to not accumulate enough stored energy to touch off an explosion
- Increased safety, which applies to devices using measures such as oil-filled enclosures to prevent contact between sparking apparatus and an explosive atmosphere
- Explosion-proof enclosures, which are designed so that an explosion within the enclosure cannot escape and touch off the surrounding atmosphere (this designation does not imply that the apparatus will survive an internal or external explosion).
In recent years standards for explosion hazard protection have become more uniform between European and North American practice. The "zone" system of classification is now used in modified form in U.S. National Electrical Code and in the Canadian electrical code. Intrinsic safety apparatus is now approved for use in North American applications, though the explosion-proof enclosures used in North America are still uncommon in Europe. Motto: E pluribus unum (1789 to 1956) (Latin: Out of Many, One) In God We Trust (1956 to present) Anthem: The Star-Spangled Banner Capital Washington, D.C. Largest city New York City Official language(s) None at federal level; English de facto Government • President • Vice President Federal republic George...
The National Electric Code manual, 2005 edition The National Electrical Code, NFPA 70 is part of the National Fire Codes published by the National Fire Protection Association (NFPA). ...
Toxic gases Electrical discharges, including partial discharge and corona, can produce small quantities of toxic gases, which in a confined space can prove a serious health hazard. These gases include ozone and various oxides of nitrogen. In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient exceeds a certain value, in situations where sparking (also known as arcing) is not favoured. ...
For other uses, see Ozone (disambiguation). ...
The term nitrogen oxide is imprecise and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5...
Lightning The largest-scale sparks are those produced naturally by lightning. Each stroke carries hundreds of thousands of amperes, at potentials of upwards of a million volts, with hundreds of joules of energy released in each strike. Each stroke lasts for only tens of microseconds. Hazards due to lightning obviously include a direct strike on persons or property. However, lightning can also create dangerous voltage gradients in the earth, and can charge extended metal objects such as telephone cables, fences, and pipelines to dangerous voltages that can be carried many miles from the site of the strike. These transferred potentials are dangerous to people, livestock, and electronic apparatus. Lightning strikes also start fires and explosions which result in fatalities, injuries, and property damage. For example, each year in North America, thousands of forest fires are started by lightning strikes. // Intracloud lightning, sheet lightning, anvil crawlers Intracloud lightning is the most common type of lightning which occurs completely inside one cumulonimbus cloud, and is commonly called an anvil crawler. ...
The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ...
Fire in San Bernardino, California Mountains (image taken from the International Space Station) A wildfire, also known as a forest fire, vegetation fire, grass fire, or bushfire (in Australasia), is an uncontrolled fire in wildland often caused by lightning; other common causes are human carelessness and arson. ...
Measures to control lightning can mitigate the hazard; these include lightning rods, shielding wires, and bonding of electrical and structural parts of buildings to form a continuous enclosure.
Lightning discharges in the atmosphere of Jupiter are thought to be the source of that planet's powerful radio frequency emissions. Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ...
See also This article treats electronics engineering as a subfield of electrical engineering, though this is not typical use in some areas. ...
Picture of a Lock used in Lock and Tag procedure for locking out hazardous energy in the United States Picture of a Tag used in Lock and Tag procedure for locking out hazardous energy in the United States Lock and tag or lock-out tag-out is a safety procedure...
The United States Occupational Safety and Health Administration (OSHA) was created by Congress under the Occupational Safety and Health Act, signed by President Richard M. Nixon on December 29, 1970. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Nikola Tesla (July 10, 1856 - c. ...
Robert Jemison Van de Graaff, (December 20, 1901 -- January 16, 1967) was an American physicist and instrument maker, and professor of physics at Princeton University. ...
// A Tesla coil is a category of disruptive discharge coils, named after their inventor, Nikola Tesla. ...
A spark plug. ...
International danger high voltage symbol. ...
External USA Catalog Standards and codes / Guideline links - NFPA 70E: Electrical Safety in the Workplace, USA
- Mike Holt NEC in the USA
- USA Department of Energy electrical safety handbook
References [1] A. H. Howatson, "An Introduction to Gas Discharges", Pergamom Press, Oxford, 1965, no ISBN page 67
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