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88-687: The Wemo Switch can be plugged into any home outlet , which can then be controlled from an iOS or Android smartphone running the Wemo App, via home Wi-Fi or mobile phone network. The Wemo Motion Sensor can be placed anywhere, as long as it can access the same Wi-Fi network as the Wemo devices it is intended to control. It can then turn on and off any of the Wemo devices connected to the Wi‑Fi network as people pass by. The Wemo Insight Switch provides information on power usage and cost estimation for devices plugged into

176-528: A fuse rated to protect its flexible cord from overload and consequent fire risk. Modern appliances may only be sold with a fuse of the appropriate size pre-installed. The United Kingdom, Ireland, and Malta use the BS ;4573 two-pin plug and socket for electric shavers and toothbrushes. The plug has insulated sleeves on the pins. Although similar to the Europlug Type ;C, the diameter and spacing of

264-551: A (non-compliant) variant of IEC 60906-1 as the national standard in 1998 under specification NBR 14136 (revised in 2002). These are used for both 220-volt and 127-volt regions of the country, despite the IEC ;60906-2 recommendation that NEMA 5-15 be used for 120 V connections. There are two types of sockets and plugs in NBR ;14136: one for 10 A, with a 4.0 mm pin diameter, and another for 20 A, with

352-468: A 10 A plug will fit all sockets but a 20 A plug will fit only 20, 25 and 32 A sockets. In New Zealand, PDL 940 "tap-on" or "piggy-back" plugs are available which allow a second 10 A plug to be fitted to the rear of the plug. In Australia these piggy-back plugs are now available only on pre-made extension leads. Australia's standard plug/socket system was originally codified as standard C112 (floated provisionally in 1937, and adopted as

440-524: A 20 A version, the original motivation to use the NEMA ;10-20 plug has ceased to exist. This Australian/New Zealand standard is used in Australia, New Zealand, Fiji, Tonga, Solomon Islands, and Papua New Guinea. It defines a plug with an earthing pin, and two flat current-carrying pins which form an inverted V-shape. The flat pins measure 6.5 by 1.6 mm (0.256 by 0.063 in) and are set at 30° to

528-523: A 4.8 mm pin diameter. This differs from IEC 60906-1 which specifies a pin diameter of 4.5 mm and a rating of 16 A. NBR 14136 does not require shutters on the apertures, a further aspect of non-compliance with IEC 60906-1. NBR 14136 was not enforced in that country until 2007, when its adoption was made optional for manufacturers. It became compulsory on 1 January 2010. Few private houses in Brazil have an earthed supply, so even if

616-640: A circuit intended for a lower rating. Glass cartridge and plug fuses allow direct inspection of the fusible element. Other fuses have other indication methods including: Some fuses allow a special purpose micro switch or relay unit to be fixed to the fuse body. When the fuse element blows, the indicating pin extends to activate the micro switch or relay, which, in turn, triggers an event. Some fuses for medium-voltage applications use two or three separate barrels and two or three fuse elements in parallel. The International Electrotechnical Commission publishes standard 60269 for low-voltage power fuses. The standard

704-432: A detachable power cord (mains flex lead) and appropriate plug in order to avoid manufacturing whole appliances, with the only difference being the type of plug. Alternatively, the plug itself can often be swappable using standard or proprietary connectors. Adaptors between standards are not included in most standards, and as a result they have no formal quality criteria defined. Physical compatibility does not ensure that

792-403: A dual 12/42 V DC electrical system that will require a fuse rated at 58 V DC. Fuses are used on power systems up to 115,000 volts AC. High-voltage fuses are used to protect instrument transformers used for electricity metering, or for small power transformers where the expense of a circuit breaker is not warranted. A circuit breaker at 115 kV may cost up to five times as much as

880-702: A fault end. The breaking capacity is the maximum current that can safely be interrupted by the fuse. This should be higher than the prospective short-circuit current . Miniature fuses may have an interrupting rating only 10 times their rated current. Fuses for small, low-voltage , usually residential, wiring systems are commonly rated, in North American practice, to interrupt 10,000 amperes. Fuses for commercial or industrial power systems must have higher interrupting ratings, with some low-voltage current-limiting high interrupting fuses rated for 300,000 amperes. Fuses for high-voltage equipment, up to 115,000 volts, are rated by

968-442: A fire when plugged into an extension cord with a current rating lower than necessary. Sometimes the cords used to plug in dual voltage 120 V / 240 V equipment are rated only for 125 V, so care must be taken by travellers to use only cords with an appropriate voltage rating. Various methods can be used to increase the number or reach of sockets. Extension cords (extension leads) are used for temporary connections when

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1056-414: A formal standard in 1938), which was based on a design patented by Harvey Hubbell and was superseded by AS 3112 in 1990. The requirement for insulated pins was introduced in the 2004 revision. The current version is AS/NZS 3112:2011, Approval and test specification – Plugs and socket-outlets . Brazil, which had been using mostly Europlugs, and NEMA 1-15 and NEMA 5-15 standards, adopted

1144-633: A list of approved plug and socket technical standards used in the member countries. The plug and socket system used in Class ;1 applications in Argentina is defined by IRAM standards. These two standards are; IRAM 2073 "Two pole plugs with earthing contact for domestic and similar purposes, rated 10 A and 20 A, 250 V AC" and IRAM 2071 "Two pole socket – outlets with earthing contact for 10 A and 20 A, 250 V AC., for fixed installations." The plug and socket system

1232-479: A low-melting solder joint that responds to long-term overload of low values compared to a short circuit. Fuse elements may be supported by steel or nichrome wires, so that no strain is placed on the element, but a spring may be included to increase the speed of parting of the element fragments. The fuse element may be surrounded by air, or by materials intended to speed the quenching of the arc. Silica sand or non-conducting liquids may be used. A maximum current that

1320-578: A maximum fuse current rating for particular circuits. A fuse can be used to mitigate short circuits , overloading, mismatched loads, or device failure. When a damaged live wire makes contact with a metal case that is connected to ground, a short circuit will form and the fuse will melt. A fuse is an automatic means of removing power from a faulty system, often abbreviated to ADS (automatic disconnection of supply). Circuit breakers can be used as an alternative to fuses, but have significantly different characteristics. Louis Clément François Breguet recommended

1408-402: A metal strip or wire fuse element, of small cross-section compared to the circuit conductors, mounted between a pair of electrical terminals, and (usually) enclosed by a non-combustible housing. The fuse is arranged in series to carry all the charge passing through the protected circuit. The resistance of the element generates heat due to the current flow. The size and construction of the element

1496-544: A particular type: Fuses come in a vast array of sizes and styles to serve in many applications, manufactured in standardised package layouts to make them easily interchangeable. Fuse bodies may be made of ceramic , glass , plastic , fiberglass , molded mica laminates , or molded compressed fibre depending on application and voltage class. Cartridge ( ferrule ) fuses have a cylindrical body terminated with metal end caps. Some cartridge fuses are manufactured with end caps of different sizes to prevent accidental insertion of

1584-518: A pin that prevents installation of similar-appearing class H fuses, which have a much lower breaking capacity and a solid blade terminal that lacks the slot of the RK type. Fuses can be built with different sized enclosures to prevent interchange of different ratings of fuse. For example, bottle style fuses distinguish between ratings with different cap diameters. Automotive glass fuses were made in different lengths, to prevent high-rated fuses being installed in

1672-714: A set of power fuses, so the resulting saving can be tens of thousands of dollars. In medium-voltage distribution systems, a power fuse may be used to protect a transformer serving 1–3 houses. Pole-mounted distribution transformers are nearly always protected by a fusible cutout , which can have the fuse element replaced using live-line maintenance tools. Medium-voltage fuses are also used to protect motors, capacitor banks and transformers and may be mounted in metal enclosed switchgear, or (rarely in new designs) on open switchboards. Large power fuses use fusible elements made of silver , copper or tin to provide stable and predictable performance. High voltage expulsion fuses surround

1760-400: A small excess. The element must not be damaged by minor harmless surges of current, and must not oxidize or change its behavior after possibly years of service. The fuse elements may be shaped to increase heating effect. In large fuses, current may be divided between multiple strips of metal. A dual-element fuse may contain a metal strip that melts instantly on a short circuit, and also contain

1848-430: A socket is not within convenient reach of an appliance's power lead. This may be in the form of a single socket on a flexible cable or a power strip with multiple sockets. A power strip may also have switches, surge voltage protection, or overcurrent protection. Multisocket adaptors (or "splitters") allow the connection of two or more plugs to a single socket. They are manufactured in various configurations, depending on

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1936-570: A switch for the selection of voltage. The plugs and sockets used in a given area are regulated by local governments. The International Electrotechnical Commission (IEC) maintains a guide with letter designations for generally compatible types of plugs, which expands on earlier guides published by the United States Department of Commerce . This is a de facto naming standard and guide to travellers. Some letter types correspond to several current ratings or different technical standards, so

2024-472: A switch. This could allow malicious attacks, such as flipping the switch at a very fast rate, which could damage certain devices and even cause electrical fires. This vulnerability has been addressed by updated firmware releases. This electronics-related article is a stub . You can help Misplaced Pages by expanding it . Electrical outlet AC power plugs and sockets connect devices to mains electricity to supply them with electrical power . A plug

2112-467: A third pin for a safety connection to earth ground. The plug is a male connector, usually with protruding pins that match the openings and female contacts in a socket. Some plugs also have a female contact, used only for the earth ground connection . Typically no energy is supplied to any exposed pins or terminals on the socket. In addition to the recessed contacts of the energised socket, plug and socket systems often have other safety features to reduce

2200-674: A three-pin socket is present it is not safe to assume that all three terminals are actually connected. Most large domestic appliances were sold with the option to fit a flying earth tail to be locally earthed, but many consumers were unsure how to use this and so did not connect it. The new standard has an earth pin, which in theory eliminates the need for the flying earth tail. BS 546, "Two-pole and earthing-pin plugs, socket-outlets and socket-outlet adaptors for AC (50-60 Hz) circuits up to 250 V" describes four sizes of plug rated at 2 A, 5 A (Type D), 15 A (Type M) and 30 A. The plugs have three round pins arranged in

2288-594: A triangle, with the larger top pin being the earthing pin. The plugs are polarised and unfused. Plugs are non-interchangeable between current ratings. Introduced in 1934, the BS 546 type has mostly been displaced in the UK by the BS 1363 standard. According to the IEC, some 40 countries use Type D and 15 countries use Type M. Some, such as India and South Africa, use standards based on BS 546. BS 1363 "13 A plugs, socket-outlets, adaptors and connection units"

2376-543: Is (empirically) determined so that the heat produced for a normal current does not cause the element to attain a high temperature. If too high a current flows, the element rises to a higher temperature and either directly melts, or else melts a soldered joint within the fuse, opening the circuit. The fuse element is made of zinc, copper, silver, aluminum, or alloys among these or other various metals to provide stable and predictable characteristics. The fuse ideally would carry its rated current indefinitely, and melt quickly on

2464-426: Is a registered trademark of a German association established to own the term). The socket has a circular recess with two round holes and two earthing clips that engage before live pin contact is made. The pins are 4.8 by 19 mm (0.189 by 0.748 in). The Schuko system is unpolarised, allowing live and neutral to be reversed. The socket accepts Europlugs and CEE 7/17 plugs and also includes CEE 7/7. It

2552-529: Is centred between the apertures, offset by 10 mm (0.394 in). The plug has two round pins measuring 4.8 by 19 mm (0.189 by 0.748 in), spaced 19 mm (0.748 in) apart and with an aperture for the socket's projecting earth pin. This standard is also used in Belgium , Poland , the Czech Republic , Slovakia and some other countries. Although the plug is polarised, CEE 7 does not define

2640-623: Is dependent upon the specific application, voltage, and current demands of the electrical circuit. Automotive fuses can be mounted in fuse blocks, inline fuse holders, or fuse clips. Some automotive fuses are occasionally used in non-automotive electrical applications. Standards for automotive fuses are published by SAE International (formerly known as the Society of Automotive Engineers). Automotive fuses can be classified into four distinct categories: Most automotive fuses rated at 32 volts are used on circuits rated 24 volts DC and below. Some vehicles use

2728-418: Is designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. These types of fuse are used on equipment such as motors, which can draw larger than normal currents for up to several seconds while coming up to speed. The I t rating is related to the amount of energy let through by the fuse element when it clears the electrical fault. This term

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2816-472: Is in four volumes, which describe general requirements, fuses for industrial and commercial applications, fuses for residential applications, and fuses to protect semiconductor devices. The IEC standard unifies several national standards, thereby improving the interchangeability of fuses in international trade. All fuses of different technologies tested to meet IEC standards will have similar time-current characteristics, which simplifies design and maintenance. In

2904-405: Is neither applicable nor permitted on plugs and sockets. CEE 7/1 unearthed sockets accept CEE 7/2 round plugs with 4.8 by 19 mm (0.189 by 0.748 in) pins. Because they have no earth connections they have been or are being phased out in most countries. Some countries still permit their use in dry areas, while others allow their sale for replacements only. Older sockets are so shallow that it

2992-416: Is normally used in short circuit conditions and the values are used to perform co-ordination studies in electrical networks. I t parameters are provided by charts in manufacturer data sheets for each fuse family. For coordination of fuse operation with upstream or downstream devices, both melting I t and clearing I t are specified. The melting I t is proportional to the amount of energy required to begin melting

3080-483: Is not significant in more traditional wire type fuses, but can be significant in other technologies such as resettable (PPTC) type fuses. Ambient temperature will change a fuse's operational parameters. A fuse rated for 1 A at 25 °C may conduct up to 10% or 20% more current at −40 °C and may open at 80% of its rated value at 100 °C. Operating values will vary with each fuse family and are provided in manufacturer data sheets. Most fuses are marked on

3168-445: Is often designed so that the earth ground contact connects before the energized circuit contacts. The assigned IEC appliance class is governed by the requirement for earthing or equivalent protection. Class I equipment requires an earth contact in the plug and socket, while Class II equipment is unearthed and protects the user with double insulation . Where a " neutral " conductor exists in supply wiring, polarisation of

3256-449: Is possible to accidentally touch the live pins of a plug. CEE 7/1 sockets also accept CEE 7/4, CEE 7/6 and CEE 7/7 plugs without providing an earth connection. The earthed CEE 7/3 and CEE 7/5 sockets do not allow insertion of CEE 7/2 unearthed round plugs. The CEE 7/3 socket and CEE 7/4 plug are commonly called Schuko , an abbreviation for Schutzkontakt , Protective contact to earth ("Schuko" itself

3344-686: Is rated at 16 A. The current German standards are DIN  49441 and DIN 49440. The standard is used in Germany and several other European countries and on other continents. Some countries require child-proof socket shutters; the DIN ;49440 standard does not have this requirement. The plug is used in most or many countries of Europe, Asia, and Africa, as well as in the countries of South Korea , Peru , Chile and Uruguay. The few European countries not using it at all are Belgium , Czech Republic , Cyprus , Ireland , Liechtenstein , Switzerland , and

3432-479: Is similar in appearance to the Australian and Chinese plugs. It has an earthing pin and two flat current-carrying pins forming an inverted V-shape (120°). The flat pins for the 10 A version measure 6.25 by 1.55 mm (0.246 by 0.061 in) and 8.0 by 1.9 mm (0.315 by 0.075 in) for the 20 A version, and are set at 30° to the vertical at a nominal pitch of 7.92 mm (0.312 in). The pin length

3520-423: Is the connector attached to an electrically-operated device, often via a cable. A socket (also known as a receptacle or outlet ) is fixed in place, often on the internal walls of buildings, and is connected to an AC electrical circuit. Inserting ("plugging in") the plug into the socket allows the device to draw power from this circuit. Plugs and wall-mounted sockets for portable appliances became available in

3608-532: Is the main plug and socket type used in the United Kingdom. According to the IEC it is also used in over 50 countries worldwide. Some of these countries have national standards based on BS 1363, including: Bahrain , Hong Kong , Ireland , Cyprus , Malaysia , Malta , Saudi Arabia , Singapore , Sri Lanka , and UAE . This plug has three rectangular pins forming an isosceles triangle. The BS 1363 plug has

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3696-515: Is the same as in the Chinese version. The earthing pin length is 21.4 mm (0.843 in) for the 10 A version and 21.8 mm (0.858 in) for the 20 A version. On the plugs, the pole length is 18.2 mm (0.717 in) for the 10 A version and 17.8 mm (0.701 in) for the 20 A version. The most important difference from the Australian plug is that the Argentine plug

3784-502: Is wired with the live and neutral contacts reversed. In Brazil, similar plugs and sockets are still commonly used in old installations for high-power appliances like air conditioners, dishwashers, and household ovens. Although being often called "Argentine plug," it is actually based on the American NEMA ;10-20 standard, and is incompatible with Argentine IRAM plugs. Since Brazil adopted the NBR 14136 standard which includes

3872-572: The Amazon Echo , Google Assistant , and Apple 's Siri (through the use of the Wemo Bridge). Wemo switches are controlled via IP networks; thus, for a switch to be controllable from a remote location, it must be open to receive connections from the Internet. In January 2013, it was revealed that the Wemo had a security flaw in its UPnP implementation that allowed an unauthorized user to take control of

3960-573: The National Electrical Code , NFPA 70 (NEC). The standard ampere ratings for fuses (and circuit breakers ) in USA/Canada are considered 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, and 6000 amperes. Additional standard ampere ratings for fuses are 1, 3, 6, 10, and 601. UL 248 currently has 19 "parts". UL 248-1 sets

4048-527: The UK , or not using it predominantly are Denmark , Faroe Island , France , Italy , Monaco , San Marino , Slovakia . French standard NF C 61-314 defines the CEE ;7/5 socket and CEE 7/6 plug, (and also includes CEE 7/7, 7/16 and 7/17 plugs). The socket has a circular recess with two round holes. The round earth pin projecting from the socket connects before the energized contacts touch. The earth pin

4136-465: The arc and increases the breaking capacity of the fuse. Medium-voltage fuses may have liquid-filled envelopes to assist in the extinguishing of the arc . Some types of distribution switchgear use fuse links immersed in the oil that fills the equipment. Fuse packages may include a rejection feature such as a pin, slot, or tab, which prevents interchange of otherwise similar appearing fuses. For example, fuse holders for North American class RK fuses have

4224-545: The 1880s, to replace connections to light sockets. A proliferation of types were subsequently developed for both convenience and protection from electrical injury . Electrical plugs and sockets differ from one another in voltage and current rating, shape, size, and connector type. Different standard systems of plugs and sockets are used around the world, and many obsolete socket types are still found in older buildings. Coordination of technical standards has allowed some types of plug to be used across large regions to facilitate

4312-509: The United States Army, and a manufacturer of sockets point out a number of safety issues with universal socket and adaptors, including voltage mismatch, exposure of live pins, lack of proper earth ground connection, or lack of protection from overload or short circuit. Universal sockets may not meet technical standards for durability, plug retention force, temperature rise of components, or other performance requirements, as they are outside

4400-483: The United States and Canada, low-voltage fuses to 1 kV AC rating are made in accordance with Underwriters Laboratories standard UL 248 or the harmonized Canadian Standards Association standard C22.2 No. 248. This standard applies to fuses rated 1 kV or less, AC or DC, and with breaking capacity up to 200 kA. These fuses are intended for installations following Canadian Electrical Code, Part I (CEC), or

4488-401: The advantage of a fuse element visible for inspection purposes, they have a low breaking capacity (interrupting rating), which generally restricts them to applications of 15 A or less at 250 V AC . Ceramic fuses have the advantage of a higher breaking capacity, facilitating their use in circuits with higher current and voltage . Filling a fuse body with sand provides additional cooling of

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4576-418: The appliance and socket match in frequency or voltage. Adaptors allow travellers to connect devices to foreign sockets, but do not change voltage or frequency. A voltage converter is required for electrical compatibility in places with a different voltage than the device is designed for. Mismatch in frequency between supply and appliances may still cause problems even at the correct voltage. Some appliances have

4664-422: The body or end caps with markings that indicate their ratings. Surface-mount technology "chip type" fuses feature few or no markings, making identification very difficult. Similar appearing fuses may have significantly different properties, identified by their markings. Fuse markings will generally convey the following information, either explicitly as text, or else implicit with the approval agency marking for

4752-439: The country and the region in which they are used, with various ratings. This allows connecting more than one electrical consumer item to one single socket and is mainly used for low power devices (TV sets, table lamps, computers, etc.). They are usually rated at 6 A 250 V, 10 A 250 V, or 16 A 250 V. This is the general rating of the adaptor, and indicates the maximum total load in amps, regardless of

4840-578: The current. It is a sacrificial device ; once a fuse has operated, it is an open circuit, and must be replaced or rewired, depending on its type. Fuses have been used as essential safety devices from the early days of electrical engineering. Today there are thousands of different fuse designs which have specific current and voltage ratings, breaking capacity, and response times, depending on the application. The time and current operating characteristics of fuses are chosen to provide adequate protection without needless interruption. Wiring regulations usually define

4928-441: The first three-pin earthed (grounded) plugs appeared. Over time other safety improvements were gradually introduced to the market. The earliest national standard for plug and wall socket forms was set in 1915. Designs of plugs and sockets have gradually developed to reduce the risk of electric shock and fire. Plugs are shaped to prevent bodily contact with live parts. Sockets may be recessed and plugs designed to fit closely within

5016-426: The fuse at rated current. There is a direct relationship between a fuse's cold resistance and its voltage drop value. Once current is applied, resistance and voltage drop of a fuse will constantly grow with the rise of its operating temperature until the fuse finally reaches thermal equilibrium. The voltage drop should be taken into account, particularly when using a fuse in low-voltage applications. Voltage drop often

5104-436: The fuse body and terminals to be reused if not damaged after a fuse operation. Fuses designed for soldering to a printed circuit board have radial or axial wire leads . Surface mount fuses have solder pads instead of leads. High-voltage fuses of the expulsion type have fiber or glass-reinforced plastic tubes and an open end, and can have the fuse element replaced. Semi-enclosed fuses are fuse wire carriers in which

5192-405: The fuse can continuously conduct without interrupting the circuit. The speed at which a fuse blows depends on how much current flows through it and the material of which the fuse is made. Manufacturers can provide a plot of current vs time, often plotted on logarithmic scales, to characterize the device and to allow comparison with the characteristics of protective devices upstream and downstream of

5280-412: The fuse element. The clearing I t is proportional to the total energy let through by the fuse when clearing a fault. The energy is mainly dependent on current and time for fuses as well as the available fault level and system voltage. Since the I t rating of the fuse is proportional to the energy it lets through, it is a measure of the thermal damage from the heat and magnetic forces that will be produced by

5368-453: The fuse. The operating time is not a fixed interval but decreases as the current increases. Fuses are designed to have particular characteristics of operating time compared to current. A standard fuse may require twice its rated current to open in one second, a fast-blow fuse may require twice its rated current to blow in 0.1 seconds, and a slow-blow fuse may require twice its rated current for tens of seconds to blow. Fuse selection depends on

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5456-403: The fusible wire itself can be replaced. The exact fusing current is not as well controlled as an enclosed fuse, and it is extremely important to use the correct diameter and material when replacing the fuse wire, and for these reasons these fuses are slowly falling from favour. These are still used in consumer units in some parts of the world, but are becoming less common. While glass fuses have

5544-459: The general requirements for fuses, while the latter parts are dedicated to specific fuses sizes (ex: 248-8 for Class J, 248-10 for Class L), or for categories of fuses with unique properties (ex: 248-13 for semiconductor fuses, 248-19 for photovoltaic fuses). The general requirements (248-1) apply except as modified by the supplemental part (240-x). For example, UL 248-19 allows photovoltaic fuses to be rated up to 1500 volts, DC, versus 1000 volts under

5632-478: The general requirements. IEC and UL nomenclature varies slightly. IEC standards refer to a "fuse" as the assembly of a fusible link and a fuse holder . In North American standards, the fuse is the replaceable portion of the assembly, and a fuse link would be a bare metal element for installation in a fuse. Automotive fuses are used to protect the wiring and electrical equipment for vehicles. There are several different types of automotive fuses and their usage

5720-412: The hot blade, so it can only be inserted one way. Wiring systems where both circuit conductors have a significant potential with respect to earth do not benefit from polarised plugs. Plugs and power cords have a rated voltage and current assigned to them by the manufacturer. Using a plug or power cord that is inappropriate for the load may be a safety hazard. For example, high-current equipment can cause

5808-428: The letter does not uniquely identify a plug and socket within the type family, nor guarantee compatibility. Physical compatibility of the plug and socket does not ensure correct voltage, frequency, or current capacity. Not all plug and socket families have letters in the IEC guide, but those that have are noted in this article, as are some additional letters commonly used by retail vendors. In Europe, CENELEC publishes

5896-522: The live wires in the wall behind it. Some also have an integrated cover (e.g. a hinged flap) covering the socket itself when not in use, or a switch to turn off the socket. Some plugs have a built-in fuse which breaks the circuit if too much current is passed. A third contact for a connection to earth is intended to protect against insulation failure of the connected device. Some early unearthed plug and socket types were revised to include an earthing pin or phased out in favour of earthed types. The plug

5984-434: The load's characteristics. Semiconductor devices may use a fast or ultrafast fuse as semiconductor devices heat rapidly when excess current flows. The fastest blowing fuses are designed for the most sensitive electrical equipment, where even a short exposure to an overload current could be damaging. Normal fast-blow fuses are the most general purpose fuses. A time-delay fuse (also known as an anti-surge or slow-blow fuse)

6072-421: The maximum voltage source it would have to disconnect. Connecting fuses in series does not increase the rated voltage of the combination, nor of any one fuse. Medium-voltage fuses rated for a few thousand volts are never used on low voltage circuits, because of their cost and because they cannot properly clear the circuit when operating at very low voltages. The manufacturer may specify the voltage drop across

6160-805: The number of sockets used (for example, if a 16 A 250 V adaptor has four sockets, it would be fine to plug four different devices into it that each consume 2 A as this represents a total load of only 8 A, whereas if only two devices were plugged into it that each consumed 10 A, the combined 20 A load would overload the circuit). In some countries these adaptors are banned and are not available in shops, as they may lead to fires due to overloading them or can cause excessive mechanical stress to wall-mounted sockets. Adaptors can be made with ceramic, Bakelite, or other plastic bodies. "Universal" or "multi-standard" sockets are intended to accommodate plugs of various types. In some jurisdictions, they violate safety standards for sockets. Safety advocates,

6248-431: The open-circuit voltage. For example, a glass tube fuse rated at 32 volts would not reliably interrupt current from a voltage source of 120 or 230 V. If a 32 V fuse attempts to interrupt the 120 or 230 V source, an arc may result. Plasma inside the glass tube may continue to conduct current until the current diminishes to the point where the plasma becomes a non-conducting gas. Rated voltage should be higher than

6336-522: The pins are slightly different and hence it will not fit into a Schuko socket. There are, however, two-pin sockets and adaptors which will accept both BS 4573 and Europlugs. The International Commission on the Rules for the Approval of Electrical Equipment ( IECEE ) was a standards body which published Specification for plugs and socket-outlets for domestic and similar purposes as CEE Publication 7 in 1951. It

6424-476: The placement of the live and neutral, and different countries have conflicting standards for that. For example, the French standard NF C 15-100 requires live to be on the right side, while Czech standard ČSN 33 2180 requires live to be on the left side of a socket. Thus, a French plug when plugged into a Czech socket (or a Czech plug when plugged into a French socket) will always have its polarity reversed, with no way for

6512-410: The plug can improve safety by preserving the distinction in the equipment. For example, appliances may ensure that switches interrupt the line side of the circuit, or can connect the shell of a screw-base lampholder to neutral to reduce electric shock hazard. In some designs, polarised plugs cannot be mated with non-polarised sockets. In NEMA 1 plugs, for example, the neutral blade is slightly wider than

6600-399: The production and import of electrical appliances and for the convenience of travellers. Some multi-standard sockets allow use of several types of plug. Incompatible sockets and plugs may be used with the help of adaptors, though these may not always provide full safety and performance. Single-phase sockets have two current-carrying connections to the power supply circuit, and may also have

6688-444: The public power grid, e.g. in transformer stations, main distribution boards, or in building junction boxes and as meter fuses. In some countries, because of the high fault current available where these fuses are used, local regulations may permit only trained personnel to change these fuses. Some varieties of HRC fuse include special handling features. The voltage rating of the fuse must be equal to or, greater than, what would become

6776-403: The recess to reduce risk of a user contacting the live pins. Contact pins may be sheathed with insulation over part of their length, so as to reduce exposure of energized metal during insertion or removal of the socket. Sockets may have automatic shutters to stop foreign objects from being inserted into energized contacts. Sockets are often set into a surround which prevents accidental contact with

6864-463: The risk of electric shock or damage to appliances. When commercial electric power was first introduced in the 1880s, it was used primarily for lighting. Other portable appliances (such as vacuum cleaners, electric fans, smoothing irons, and curling-tong heaters) were connected to light-bulb sockets. As early as 1885 a two-pin plug and wall socket format was available on the British market. By about 1910

6952-463: The round earthing pin permanently mounted in the socket; CEE 7/6 plugs are not compatible with Schuko sockets due to the presence of indentations on the side of the recess, as well as the earth clips. CEE 7/7 plugs have been designed to solve this incompatibility by being able to fit in either type of socket. Sales and installations of 7/5 sockets are legally permitted in Denmark since 2008, but

7040-881: The scope of national and international technical standards. A technical standard may include compatibility of a socket with more than one form of plug. The Thai dual socket is specified in figure 4 of TIS 166-2549 and is designed to accept Thai plugs, and also Type A, B, and C plugs. Chinese dual sockets have both an unearthed socket complying with figure 5 of GB 1002-2008 (both flat pin and 4.8 mm round pin), and an earthed socket complying with figure 4 of GB 1002-2008. Both Thai and Chinese dual sockets also physically accept plugs normally fitted to 120 V appliances (e.g. 120 V rated NEMA 1-15 ungrounded plugs). This can cause an electrical incompatibility, since both states normally supply residential power only at 220 V. Commonly, manufacturers provide an IEC 60320 inlet on an appliance, with

7128-427: The sockets are hard to find in physical stores, and installation is exceedingly rarely performed. Fuse (electrical) In electronics and electrical engineering , a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting

7216-486: The switch. The Wemo Light Switch is for use where a light is controlled by a single light switch. Multi-way switching is not supported at this time but can be approximated by installing a Wemo Light Switch at each location. The Wemo App controls the Wemo devices from anywhere in the world as long as the Wemo devices' wireless network is connected to the Internet. Wemo devices can also be controlled using IFTTT technology. Wemo devices can also be controlled by voice through

7304-650: The total apparent power (megavolt-amperes, MVA ) of the fault level on the circuit. Some fuses are designated high rupture capacity (HRC) or high breaking capacity (HBC) and are usually filled with sand or a similar material. Low-voltage high rupture capacity (HRC) fuses are used in the area of main distribution boards in low-voltage networks where there is a high prospective short circuit current. They are generally larger than screw-type fuses, and have ferrule cap or blade contacts. High rupture capacity fuses may be rated to interrupt current of 120 kA. HRC fuses are widely used in industrial installations and are also used in

7392-425: The use of reduced-section conductors to protect telegraph stations from lightning strikes ; by melting, the smaller wires would protect apparatus and wiring inside the building. A variety of wire or foil fusible elements were in use to protect telegraph cables and lighting installations as early as 1864. A fuse was patented by Thomas Edison in 1890 as part of his electric distribution system. A fuse consists of

7480-476: The user to remedy this situation apart from rewiring the plug. One approach for resolving this situation is taken in Poland, where CEE 7/5 sockets are typically installed in pairs, the upper (upside-down) one having the "French" polarity and the lower one having the "Czech" polarity, so that the user can choose what to plug where. CEE 7/4 (Schuko) plugs are not compatible with the CEE 7/5 socket because of

7568-639: The vertical at a nominal pitch of 13.7 mm (0.539 in). Australian and New Zealand wall sockets (locally often referred to as power points ) almost always have switches on them for extra safety, as in the UK. An unearthed version of this plug with two angled power pins but no earthing pin is used with double-insulated appliances, but the sockets always include an earth contact. There are several AS/NZS 3112 plug variants, including ones with larger or differently shaped pins used for devices drawing 15, 20, 25 and 32  A . These sockets accept plugs of equal or lower current rating, but not higher. For example,

7656-412: The wrong fuse rating in a holder, giving them a bottle shape. Fuses for low voltage power circuits may have bolted blade or tag terminals which are secured by screws to a fuseholder. Some blade-type terminals are held by spring clips. Blade type fuses often require the use of a special purpose extractor tool to remove them from the fuse holder. Renewable fuses have replaceable fuse elements, allowing

7744-702: Was last updated by Modification 4 in March 1983. CEE 7 consists of general specifications and standard sheets for specific connectors. Standard plugs and sockets based on two round pins with centres spaced at 19 mm are in use in Europe, most of which are listed in IEC/TR ;60083 "Plugs and socket-outlets for domestic and similar general use standardized in member countries of IEC." EU countries each have their own regulations and national standards; for example, some require child-resistant shutters, while others do not. CE marking

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