I.S. 10101 / ET101 Wiring Rules flashcards
I.S. 10101 / ET101 Wiring Rules · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Exposed-conductive-part
- A conductive part of equipment that can be touched, is not live in normal use, but may become live under fault conditions; it requires protective earthing.
- Extraneous-conductive-part
- A conductive part not forming part of the installation that may introduce earth potential, such as metallic water or gas pipes and structural steel.
- Basic protection
- Protection against electric shock under normal conditions, achieved by insulation, barriers or enclosures, or by placing live parts out of reach.
- Fault protection
- Protection against electric shock under single-fault conditions, achieved by automatic disconnection, double insulation, or electrical separation.
- Diversity factor
- An assumed fraction applied to the sum of connected loads to estimate maximum demand, valid only where the load pattern justifies the reduction.
- Prospective fault current
- The current that would flow at a point if a short circuit of negligible impedance occurred there; used to select protective devices and cables.
- TN-C-S system
- An earthing arrangement where the supply neutral also serves as the protective conductor and is split into separate neutral and protective conductors at the origin.
- Voltage drop limit
- The maximum permitted reduction in voltage between the origin and the load, assessed separately for lighting and power circuits to ensure equipment operates correctly.
- Earth fault loop impedance
- The total impedance of the path from the origin through the phase conductor, fault, and protective conductor back to the source, denoted Zs.
- Disconnection time
- The maximum time permitted for a protective device to clear a fault; for TN final circuits up to 32 A it is typically 0.4 seconds.
- TT system disconnection rule
- In a TT system the earth electrode resistance times the RCD residual current must not exceed 50 volts, expressed as Ra × IΔn ≤ 50 V.
- SELV system
- A system operating at a safe extra-low voltage with no connection to earth, so that contact with live parts cannot cause a dangerous shock.
- Overload coordination rule
- The design current must not exceed the device rating, which must not exceed the cable capacity, and the device must operate before the cable overheats.
- Adiabatic withstand
- The cable or protective conductor must withstand fault energy, verified by k²S² being at least the let-through energy I²t of the protective device.
- Surge protective device
- A device that limits transient overvoltages by diverting surge current to earth, selected by voltage protection level and discharge current rating.
- Grouping correction factor
- A factor less than one applied to cable current rating when cables are bunched, because mutual heating reduces the ability to dissipate heat.
- Reference installation method
- A classification of how a cable is mounted (clipped, in conduit, buried) that determines its tabulated current-carrying capacity.
- Circuit integrity
- The ability of a wiring system to continue functioning during a fire, required for circuits supplying safety services and escape routes.
- Protective conductor sizing
- The protective conductor cross-section is related to the phase conductor size, with larger phase conductors allowing a reduced ratio subject to a minimum.
- Maximum conductor temperature
- The highest temperature a cable insulation may safely reach in normal or fault operation, determined by the insulation material such as PVC or XLPE.
- Neutral conductor reduction
- The neutral cross-section may be smaller than the phase conductor only where load and harmonic conditions permit, otherwise it must be adequate for the load.
- Main earthing terminal
- The terminal that connects the earthing conductor, protective conductors, and main protective bonding conductors together in an installation.
- Main protective bonding
- Connection of extraneous-conductive-parts to the main earthing terminal to prevent dangerous potential differences within the installation.
- Supplementary bonding
- Local connection of simultaneously accessible exposed and extraneous-conductive-parts where automatic disconnection alone cannot ensure safety.
- PEN conductor
- A combined protective and neutral conductor that carries both functions; it may only be used in fixed wiring where the supply arrangement permits.
- Isolation
- Cutting off supply from all live conductors for maintenance or repair, using a device with a clear break that can be secured against reconnection.
- Functional switching
- Control of equipment in normal use without providing isolation; it does not necessarily disconnect all live conductors.
- Discrimination
- Coordination of protective devices so that the device nearest a fault operates first, limiting the extent of supply interruption.
- Bathroom zones
- Defined regions around a bath or shower (0, 1 and 2) that restrict the type and location of electrical equipment according to water exposure.
- Construction site protection
- Harsh and wet conditions require robust equipment, reduced voltages where appropriate, and 30 mA RCD protection for socket-outlets.
- Insulation resistance test
- A test performed with the installation isolated to confirm insulation is sound, with results compared against the minimum value for the circuit voltage.
- Polarity verification
- A check that all switches and protective devices are connected in the phase conductor and that socket-outlet connections are correct.