In the latest guidelines for electrical wiring in residential buildings (2008) handbook, the overall residential wiring need to be protected by a residual current device of sensitivity not exceeding 100 mA. Additionally, all power sockets need to be protected by a residual current device of sensitivity not exceeding 30 mA and all equipment in wet places (water heater, water pump) need to be protected by a residual current device of sensitivity not exceeding 10 mA.
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Belgian domestic installations are required to be equipped with a 300 mA 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.
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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 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.
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Internal mechanism of RCD Opened 3-phase residual-current device 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 could be dangerous on unexpected re-energisation.
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As a result, plugging or unplugging while powered up can result in very loud noises in speakers. If the ground voltage difference is small, it tends to only cause hum and clicks. A residual current device can be incorporated into a system to reduce but not eliminate the risks caused by a floating ground.
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Red dot design award for A&E; Design 1999 and 2001. The folding stool "Stockholm II" (red) and child version "Snupi". Ehrichs latest work for A&E; Design: residual-current device (2015) and timer (2014). The first commission of the new design consultancy was to create a paintbrush with a comfortable grip, made of polypropylene plastic.
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Until the 1950s, isolated ground domestic mains supplies tended to have no Residual-Current Device (RCD) or Earth Leakage Circuit Breaker (ELCB), and too high a ground impedance to blow a fuse if a live-to-earth fault occurred. This could leave metalwork in the house live. The use of Residual Current Devices (RCDs) or formerly ELCBs with such installs solved this problem. Such installs are called EEBAD (Earthed Equipotential Bonding and Automatic Disconnection).
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The issue of security becomes increasingly important as it increases the capillary diffusion of the electrical systems, which make it more likely an accidental contact with an electrical conductor in tension. It is then built and patented a circuit breaker called a “residual current device” (1965); it's high-power switching, with the addition of a differential transformer. The company is also known over the years for the plaques that surround the normal switches inside the house. With the Series Living (1985) and the subsequent Light and Living International (1996) are introduced devices of multifunctional control of individual components.
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The risk of electrical shock on construction sites can be reduced by several measures, including reduction of the normal 230 volt distribution voltage to 110 volts for electrical lighting and power tools. By using a centre-tapped transformer, each conductor of the circuit is only at 55 volts with respect to earth. This reduces the chance of dangerous electrical shock when using power tools in wet locations.RRC International, Health and Safety at Work For Dummies, John Wiley & Sons, 2016, Chapter 13 section Reduced voltage systems Where 230 volts must be used, a residual current device (RCD) can be used to detect small leakage currents and automatically isolate faulty equipment.
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If the short-circuit current is lower than this figure, special precautions need to be taken to make sure that the system is safe; those usually include using a residual- current device (a.k.a. ground fault interrupter) for extra protection. The short-circuit current available on the electrical outlets is often tested when inspecting new electrical installations to make sure that the short-circuit current is within reasonable limits. A high short-circuit current on the outlet also shows that the resistance from the electrical panel to the outlet is low, so there won't be an unacceptably high voltage drop on the wires under normal load.
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The company is part of the International Group Legrand and operates both on the Italian market and on the Worldwide one with over 60 offices abroad. The main products in the field of electrical equipment are traditional and domotics switches, plates, residual current devices, intercoms and video intercoms. The main office and headquarter is in Varese, where there are 1500 employees, split between design, production, quality, test, marketing, administrative and commercial offices. Other important locations are Erba, where all the domotics products and video intercoms are developed and produced; Ospedaletto Lodigiano where is located the central warehouse; Bodio, where the plaques are made; Azzano San Paolo and Torre del Greco, where are developed and manufactured devices industrial and residual current device.
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If the wrong type was used on an installation, the level of protection given could be substantially less than that intended, in particular the voltage operated type can only protect against faults or shocks to metalwork connected to the circuit ground, connected to the VOELCB, it cannot detect current leaving a live wire and running to ground by another path, such as via a person standing on the earth. To eliminate this confusion, the IEC decided to apply the term residual current device (RCD) to differential-current-operated ELCBs. Residual current refers to any residue when comparing current in the outbound and return currents in the circuit. In a single phase circuit this is simply the live or phase current minus the neutral current.
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If large enough, this current will trip an over-current device (fuse or circuit breaker (CB)) and disconnect the supply. The disconnection time has to be fast enough not to allow fibrillation to start if a person is in contact with the casing at the time. This time and the current rating in turn sets a maximum earth resistance permissible. To provide supplementary protection against high- impedance faults it is common to recommend a residual-current device (RCD) also known as a residual current circuit breaker (RCCB), ground fault circuit interrupter (GFCI), or residual current operated circuit-breaker with integral over-current protection (RCBO), which will cut off the supply of electricity to the appliance if the currents in the two poles of the supply are not equal and opposite.
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