"a register of approved electricians. It was incorporated on 10 August 1956, and since 1 October 2005, it has been registered as The Electrical Safety Council. Electrical contractors register with the organisation to become approved contractors, meeting the NICEIC's specification of training. If work undertaken by the approved contractor is not up-to-standard, the NICEIC will correct it if necessary. Work is checked by 54 local Area Engineers. Many local authorities only give work to NICEIC-approved electricians. Most electrical items in domestic wiring are controlled from the consumer unit with its residual-current device (RCD), which since 2001 has to be installed."
"Residual-current device A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a device that instantly breaks an electric circuit to prevent serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human falls after receiving a shock, or if the person touches both conductors at the same time. RCD is the name used in the United Kingdom. In the United States and Canada, the terms ground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or appliance leakage current interrupter (ALCI) are used. If the RCD device has additionally overcurrent protection integrated"
"residual-current devices (RCDs) or residual current breakers with overcurrent protection (RCBOs). The RCDs are used for earth leakage protection, while RCBOs combine earth leakage protection with overcurrent protection. In a UK-style board, breaker positions are numbered top to bottom in the left-hand column, then top to bottom in the right column. Since some point in the 1970s, the supply voltage in UK domestic premises has been 240 V AC (RMS) at 50 Hz. In 1988, a Europe-wide agreement was reached to unify the various national voltages, which ranged, at the time, 220–240 V, to a common European standard of 230"
"the electrical accident the RCD is supposed to prevent (examples might be a supply to a critical factory process, or to life support equipment), RCDs may be omitted, providing affected circuits are clearly labelled and the balance of risks considered, this may include the provision of alternative safety measures. Residual-current device A residual-current device (RCD), or residual-current circuit breaker (RCCB), is a device that instantly breaks an electric circuit to prevent serious harm from an ongoing electric shock. Injury may still occur in some cases, for example if a human falls after receiving a shock, or if the person touches"
"all domestic installations to protect all the lines. The law was recently updated to mandate at least two separate RCDs for separate domestic circuits. Short-circuit and overload protection has been compulsory since 1968. From January 2003, all new circuits originating at the switchboard supplying lighting or socket outlets (power points) in domestic buildings must have RCD protection. Residential facilities (such as boarding houses, hospitals, hotels and motels) will also require RCD protection for all new circuits originating at the switchboard supplying socket outlets. These RCDs will normally be located at the switchboard. They will provide protection for all electrical wiring"
"type was used on an installation, the level of protection given could be substantially less than that intended. To eliminate this confusion, IEC decided to apply the term residual current device (RCD) to differential-current-operated ELCBs. Residual current refers to any current over and above the load current... An ELCB is a specialised type of latching relay that has a building's incoming mains power connected through its switching contacts so that the ELCB disconnects the power when earth leakage is detected. The ELCB detects fault currents from live to the Earth (ground) wire within the installation it protects. If sufficient voltage"
"a hybrid of ELPD and RCCB. Turkey requires the use of RCDs with no more than 30 mA and 300 mA in all new homes since 2004. This rule was introduced in RG-16/06/2004-25494. The previous editions of the IEE Electrical Wiring Regulations required use of RCDs for socket outlets that were liable to be used by outdoor appliances. Normal practice in domestic installations was to use a single RCD to cover all the circuits requiring RCD protection (typically sockets and showers) but to have some circuits (typically lighting) not RCD protected. This was to avoid a potentially dangerous loss of"
"of the RCD would disconnect power from all the protected circuits. The current edition (18th) of the regulations requires that all socket outlets in most installations have RCD protection, though there are exemptions. Non armoured cables buried in walls must also be RCD protected (again with some specific exemptions). Provision of RCD protection for circuits present in bathrooms and shower rooms reduces the requirement for supplementary bonding in those locations. Two RCDs may be used to cover the installation, with upstairs and downstairs lighting and power circuits spread across both RCDs. When one RCD trips, power is maintained to at"
"if the device is operational and can test the wiring to the RCD. Such a test may be performed on installation of the device and at any ""downstream"" outlet. (Upstream outlets are ""not"" protected.) To avoid needless tripping, only one RCD should be installed on any single circuit (excluding corded RCDs, such as bathroom small appliances). A residual-current circuit breaker cannot remove all risk of electric shock or fire. In particular, an RCD alone will not detect overload conditions, phase-to-neutral short circuits or phase-to-phase short circuits (see three-phase electric power). Over-current protection (fuses or circuit breakers) must be provided. Circuit"
"""AC"" RCD's since 1987, to be used to protect humans against electrical shocks. It must be Type ""A"" or type ""B"". According to Regulation 36 of the Electricity Regulations 1990 a) For a place of public entertainment, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 10 mA. b) For a place where the floor is likely to be wet or where the wall or enclosure is of low electrical resistance, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 10 mA. c) For"
"generic function of a circuit breaker, RCD or a fuse, as an automatic means of removing power from a faulty system is often abbreviated as OCPD (Over Current Protection Device). An early form of circuit breaker was described by Thomas Edison in an 1879 patent application, although his commercial power distribution system used fuses. Its purpose was to protect lighting circuit wiring from accidental short circuits and overloads. A modern miniature circuit breaker similar to the ones now in use was patented by Brown, Boveri & Cie in 1924. Hugo Stotz, an engineer who had sold his company to BBC,"
"to the appliance. The test button (8) allows the correct operation of the device to be verified by passing a small current through the orange test wire (9). This simulates a fault by creating an imbalance in the sense coil. If the RCD does not trip when this button is pressed, then the device must be replaced. Residual-current and overcurrent protection may be combined in one device for installation into the service panel; this device is known as a GFCI (ground fault circuit interrupter) breaker in the USA and Canada, and as an RCBO (residual-current circuit breaker with overload protection)"
"breakers that combine the functions of an RCD with overcurrent protection respond to both types of fault. These are known as RCBOs and are available in 2-, 3- and 4-pole configurations. RCBOs will typically have separate circuits for detecting current imbalance and for overload current but use a common interrupting mechanism. An RCD helps to protect against electric shock when current flows through a person from a phase (live / line / hot) to earth. It cannot protect against electric shock when current flows through a person from phase to neutral or from phase to phase, for example where a"
"for any reason, then a single-pole RCD will leave this conductor still connected to the circuit when it detects the fault. RCDs are designed to disconnect the circuit if there is a leakage current. By detecting small leakage currents (typically 5–30 mA) and disconnecting quickly enough (<30 ms), they may prevent electrocution. They are an essential part of the automatic disconnection of supply (ADS), i.e. to switch off when a fault develops, rather than rely on human intervention, one of the essential tenets of modern electrical practice. To prevent electrocution, RCDs should operate within 25–40 milliseconds with any leakage currents"
"interrupting power, AFCIs helps reduce the likelihood of the home's electrical system being an ignition source of a fire. Dual Function AFCI/GFCI devices offer both electrical fire prevention and shock prevention in one device making them a solution for many rooms in the home, especially when replacing an existing standard receptacle or existing ungrounded receptacle. Major differences exist regarding the manner in which an RCD-unit will act to disconnect the power to a circuit or appliance. There are four situations in which different types of RCD-units are used: 1. At the Consumer Power-Distribution Unit (CPDU) - usually in conjunction with"
"IEC Standard 60755 (""General requirements for residual current operated protective devices"") defines three types of RCD depending on the waveforms and frequency of the fault current. The BEAMA RCD Handbook - Guide to the Selection and Application of RCDs summaries this as follows: and notes that these designations have been introduced because some designs of type A and AC RCD can be disabled if a DC current is present that saturates the core of the detector. The surge current refers to the peak current an RCD is designed to withstand using a test impulse of specified characteristics. The IEC 61008"
"30 mA RCDs will be required for socket outlets that are for use by ordinary persons and are intended for general use. This improves the level of protection against electrical shock in the UK to a level comparable to that in other EU countries. The 17th edition and its amendments incorporated new sections relating to microgeneration and solar photovoltaic systems, non-combustible consumer units, RCDs, and breakers (including high resilience breaker layout). BS 7671 British Standard BS 7671 ""Requirements for Electrical Installations. IET Wiring Regulations"", informally called in the electrical community The ""Regs"", is the national standard in the United Kingdom"
"distribution board, which provides protection in case of damage to fixed wiring; In Europe socket-based RCDs are primarily used for retro-fitting. Regulations differ widely from country to country. In most countries, not all circuits in a home are protected by RCDs. If a single RCD is installed for an entire electrical installation, any fault may cut all power to the premises. In Australia, residual current devices have been mandatory on power circuits since 1991 and on light circuits since 2000. A minimum of two RCDs is required per domestic installation. All socket outlets and lighting circuits are to be distributed"
"an installation where hand-held equipment, apparatus or appliance is likely to be used, protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 30 mA. d)For an installation other than the installation in (a), (b) and (c), protection against earth leakage current must be provided by a residual current device of sensitivity not exceeding 100 mA. The Italian law (n. 46 March 1990) prescribes RCDs with no more than 30 mA residual current (informally called ""salvavita"" — life saver, after early Bticino models, or differential circuit breaker for the mode of operation) for"
"to neutral)). However, a RCD and a MCB often come integrated in the same device, thus being able to detect both supply imbalance and overload current. Such a device is called The diagram depicts the internal mechanism of a residual-current device (RCD). The device is designed to be wired in-line in an appliance power cord. It is rated to carry a maximal current of 13 A and is designed to trip on a leakage current of 30 mA. This is an active RCD; that is, it latches electrically and therefore trips on power failure, a useful feature for equipment that"
"least one lighting and power circuit. Other arrangements, such as the use of RCBOs, may be employed to meet the regulations. The new requirements for RCDs do not affect most existing installations unless they are rewired, the distribution board is changed, a new circuit is installed, or alterations are made such as additional socket outlets or new cables buried in walls. RCDs used for shock protection must be of the 'immediate' operation type (not time-delayed) and must have a residual current sensitivity of no greater than 30 mA. If spurious tripping would cause a greater problem than the risk of"
"circuit breaker) in lieu of rewiring the entire circuit with a grounding conductor. In such cases the receptacles must be labeled ""no equipment ground"" and ""GFCI protected""; GFCI manufacturers typically provide tags for the appropriate installation description. GFCIs approved for protection against electric shock trip at 5 mA within 25 ms. A GFCI device which protects equipment (not people) is allowed to trip as high as 30 mA of current; this is known as an Equipment Protective Device (EPD). RCDs with trip currents as high as 500 mA are sometimes deployed in environments (such as computing centers) where a lower"
"Constant-current diode Constant-current diode is an electronic device that limits current to a maximal specified value for the device. It is known as current-limiting diode (CLD), current-regulating diode (CRD). These diodes consist of an n-channel JFET with the gate shorted to the source, which functions like a two-terminal current limiter or current source (analogous to a voltage-limiting Zener diode). They allow a current through them to rise to a certain value, and then level off at a specific value. Unlike Zener diodes, these diodes keep the current constant instead of the voltage constant. These devices keep the current flowing through"
"threshold would carry an unacceptable risk of accidental trips. These high-current RCDs serve for equipment and fire protection instead of protection against the risks of electrical shocks. In the United States the American Boat and Yacht Council requires both GFCIs for outlets and Equipment Leakage Circuit Interrupters (ELCI) for the entire boat. The difference is GFCIs trip on 5 mA of current whereas ELCIs trip on 30 mA after up to 100 ms. The greater values are intended to provide protection while minimizing nuisance trips. In Norway, it has been required in all new homes since 2002, and on all"
"ACR requires both SDS1 & SDS2 to be online and fully operational before they will operate at any power level. Safety Shutdown System 1 (SDS1): SDS1 is designed to rapidly and automatically terminate reactor operation. Neutron-absorbing rods (control rods that shut down the nuclear chain reaction) are stored inside isolated channels located directly above the reactor vessel (calandria) and are controlled via a triple-channel logic circuit. When any 2 of the 3 circuit paths are activated (due to sensing the need for emergency reactor trip), the direct current-controlled clutches that keep each control-rod in the storage position are de-energized. The"
"Radar detector detector A radar detector detector (RDD) is a device used by police or law enforcement in areas where radar detectors are declared illegal. Radar detectors are built around a superheterodyne receiver, which has a local oscillator that radiates slightly. It is therefore possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz for the intermediate frequency). Some radar guns are equipped with such a device. However, like any device that detects stray emissions from electronic equipment, it is easily defeated by using adequate shielding. The"
"residual current device that protects all circuits. Furthermore, at least one 30 mA residual current device is required that protects all circuits in ""wet rooms"" (e.g. bathroom, kitchen) as well as circuits that power certain ""wet"" appliances (washing machine, tumble dryer, dishwasher). Electrical underfloor heating is required to be protected by a 100 mA RCD. These RCDs must be of type A. Since NBR 5410 (1997) residual current devices and grounding are required for new construction or repair in wet areas, outdoor areas, interior outlets used for external appliances, or in areas where water is more probable like bathrooms and"
"other current path. Automatic disconnection and a measure of shock protection is therefore still provided even if the earth wiring of the installation is damaged or incomplete. For an RCD used with three-phase power, all three live conductors and the neutral (if fitted) must pass through the current transformer. Electrical plugs with incorporated RCD are sometimes installed on appliances that might be considered to pose a particular safety hazard, for example long extension leads, which might be used outdoors, or garden equipment or hair dryers, which may be used near a bath or sink. Occasionally an in-line RCD may be"
"to their 'Lumo' consumer unit to enhance visibility in dark locations such as under staircases. With the introduction of the recent (BS 7671:2008 incorporating amendment no 1: 2011) 17th Edition IET Wiring Regulations consumer units in the UK must provide RCD protection to all cables embedded in walls excepting high integrity circuits such as those for burglar alarms or smoke alarms. Consumer units have different methods of protecting circuits. A dual split-load consumer unit can be arranged as follows: RCD 1 RCD 2 By alternating the circuits like this, power will always be present on one floor if either RCD"
"to 24 ways for devices (some of which might occupy two ways), and will be split into two or more sections (e.g. a non-RCD section for alarms etc., an RCD-protected section for socket outlets, and an RCD-protected section for lighting and other built-in appliances). Secondary CUs used for outbuildings usually have 1 to 4 ways plus an RCD. Recent (pre-17th edition wiring regulations) CUs would not normally have RCD protected sections for anything other than socket outlets, though some older CUs featured RCD Incomers. Before 1990, RCDs (and split busbars) were not standard in CUs. Fuse Boxes normally use cartridge"
"Western Electric System 1393 Radar Course Directing Central The Western Electric ""System 1393"" Radar Course Directing Central (RCDC) was a Cold War complex of radar/computer systems within the overall Improved Nike Hercules Air Defense Guided Missile System (separate from the missiles, storage and launch equipment, and command post equipment). The RCDC was installed at the ""battery control areas"" (Integrated Fire Control areas) of ~ each which was for commanding a nearby missile Launching Area (LA), firing a missile from the LA, and guiding a launched missile to a burst point near an enemy aircraft. The Radar Course Directing Central included"
"High Resistance Connection A high-resistance connection (HRC) is a problem that results from loose or poor connections in traditional electrical accessories and switchgear which can cause heat to develop, capable of starting a fire. Safety devices such as fuses and residual-current devices (RCDs) are unable to detect thermal rise and disconnect the electrical supply because they cannot sense HRC. A safety device to prevent HRC operates by effectively monitoring for abnormal thermal rise and will prevent ignition, smoke or burning odour of the electrical accessory or electrical installation. An example extract from the National Union of Teachers (NUT) Fire Safety"
"however these issues do limit the effectiveness of RCDs in other applications such as industry. Even with the installation of an RCD, exposure to electricity can still prove lethal. In large electric power systems, supervisory control and data acquisition (SCADA) is used for tasks such as switching on generators, controlling generator output and switching in or out system elements for maintenance. The first supervisory control systems implemented consisted of a panel of lamps and switches at a central console near the controlled plant. The lamps provided feedback on the state of the plant (the data acquisition function) and the switches"