(Note, it is not intended that the fuse should protect the appliance itself, for which it is still necessary for the appliance designer to take the necessary precautions.)
The duration of this voltage must therefore be limited, which is done by "automatic disconnection of supply" (ADS) either by overcurrent protection devices (OCPDs), or by residual current devices (RCDs) that specifically detect the current escaping from the intended circuit, allowing them to have a far lower tripping current. In some cases the installation of 12 V downlighters is notifiable whereas the installation of 230 V mains downlighters is not. Examples of faults are an insulation failure between a line conductor and a metallic frame of an appliance within the installation, a break in a combined protective-earth and neutral conductor in the supply, or an insulation fault in the supply transformer causing the whole low-voltage system to rise in potential.) Standard sizes have a conductor cross sectional area of 1, 1.5, 2.5, 4, 6 and 10 mmThe earthing conductor is uninsulated since it is not intended to have any voltage difference from surrounding earthed articles. Additionally, if the insulation of a line or neutral wire becomes damaged, then the wire is more likely to earth itself on the bare earth conductor and in doing so either trip the Earthing and bonding are used together to provide shock protection by avoiding a dangerous combination of magnitude and duration of the voltage to which people may be exposed in the event of a fault within the installation or outside the installation.
The grey colour was adopted by cable manufacturers to match older lead sheathed flat cables, with some manufacturers using a silver grey polyvinyl chloride. This standard includes preferred voltage ratings up to and including 1,200kV maximum system voltage. The UK installation-accessory industry is therefore occasionally criticised for being overly conservative.The commonly used domestic wall-mount socket used in the UK for currents up to 13 A is defined in Many high load non-UK-sourced appliances need IEC 60309 connectors (or wiring via a British Standard "20 A connection unit") in the UK because of the lower plug rating. Before the 2008 regulations, such shaving sockets were the only sockets permitted in a bathroom or shower room.
Voltage, frequency, and plug type vary, but large regions may use common standards. Physical compatibility of receptacles may not ensure compatibility of voltage, frequency, or connection to earth (ground), including Although useful for quick reference, especially for travellers, Voltages in this article are the nominal single-phase supply voltages, or split-phase supply voltages. Supplementary bonding connects simultaneously touchable conductive parts in local parts of an installation: the parts may be pairs of ECPs on different circuits, or an ECP and extraneous conductive parts.
The UK changed colour codes three decades after most other European countries, as in 1977 the change of neutral and phase colours was not considered safe by the IEE. endobj Three-phase and industrial loads may have other voltages. This will typically have a value from 40–100 A.