Properties, applications and limitations of wiring systems

Cards (41)

  • Types of wiring enclosures
    • Conduit
    • Trunking
    • Cable tray
    • Ladder
    • Basket
  • What are the wiring types
    • PVC
    • SWA
    • MICC
  • What are the basic parts of cables
    • Conductor
    • Insulator
    • Sheathing
  • What does conductors consist of
    • Copper
    • Aluminium
    • Cadmium copper
    • Steel reinforced aluminium
    • Copper sheathed aluminium
    • Silver
  • What are the insulator types
    • PVC(Polyvinyl chloride)
    • XLPE(Cross-linked Polyethylene)
    • Synthetic rubbers
    • Magnesium oxide
    *They give basic protection
  • What are the types of sheathing
    • PVC
    • XPLE
    • Synthetic rubber
    • Copper
    *Sheathing gives machanical protection
  • PVC cable
    Conductors for cables are either made of 'copper' or 'aluminium', and may be 'standard' or 'solid':
    • Solid conductors are size to 2.5mm²
    • Solid conductors are only used in fixed wiring instillations and may be shaped in larger cables
    • Standard conductors are more flexible and conductor sizes from 1.0mm² to 25mm² contain strands
  • The characteristics of Polyvinyl chloride (PVC)

    • A synthetic polymer (plastic) contains carbon, hydrogen and chlorides relatively cheap and easy to mould material which can be made in many forms
    • It's robust, chemically inert, good ageing and fire-resistant properties has very little absorption to water
    • More resistant to sunlight and weathering than rubber, but will crack and harden in the presence of oil or grease
  • What are the characteristics of Polyvinyl chloride (PVC)
    • Its robust
    • Chemically insert
    • Good ageing
    • Fire-resisting properties
    • Very little absorption to water
  • The advantage of Polyvinyl chloride (PVC)
    • More resistant to weathering and sunlight than rubber
  • The disadvantage of Polyvinyl chloride (PVC)
    • Harden and cracks in the presence of oil or grease
    • Softens at hight temperatures and possible insulation failure
    • PVC may become brittle
  • The uses of PVC
    Its used as a insulator or sheathing
  • if the PVC ever gets damaged (burnt), the material will release a dense smoke and corrosive fumes
  • What does 6491X mean

    Single-core PVC-insulated unsheathed cables (hard wiring cable)
  • What is 6491X used for

    • Thermoplastic (polyvinyl chloride) insulated cables are used for general-purpose lighting and power systems.
    • They have a maximum working temperature of 70°C, which governs the cables' ability to carry current, along with their cross-sectional area (CSA). 
  • What is the characteristics of 6491X
    • Designed for drawing into trunking and conduit systems because the insulation does not provide mechanical protection by itself.
    • Construction is that of PVC insulated Solid or Stranded copper conductor coloured brown or blue. 
  • What other colours does 6491X come as
    • Other colours include grey, white and green&yellow stripes for use as a circuit protective conductor (CPC). 
  • The uses of a PVC insulated and unsheathed cables
    • This cable is used for domestic and industrial wiring and is suitable for service wiring where a circuit protective conductor is required for all circuits and there is little risk of mechanical damage. 
  • What can you do with PVC insulated and unsheathed cables
    • May be clipped direct to a surface, sunk in plaster or installed conduit or trunking It is the simplest and least expensive cable. 
    • Construction is of one to three core copper, solid or stranded conductors. 
  • The characteristics of a PVC insulated and unsheathed cable
    • The conductors are covered with a colour coded PVC insulation and then contained in a PVC outer sheath which provides minimal protection from mechanical damage. 
  • What are the colours of a PVC insulated and unsheathed cable
      
    • The core colours are brown, blue black and grey the CPC is uninsulated copper and the outer sheath colour is normally white or grey 
  • The advantages of PVC insulated and unsheathed cable
    • Cheap to install - (no special techniques needed) 
    • Insulation is waterproof - (not connections)
    • Long life time - should last 30 yrs of normal service 
    • Easy to install - no special techniques needed 
    • Cheap to buy 
  • The disadvantages of PVC insulated and unsheathed cables
    • Insulation becomes brittle below 4°C  
    • Insulation becomes soft above 60°C  
    • Poor mechanical strength
    • Affected by sunlight (become brittle under UV light
  • The uses for Single core PVC Insulated sheathed cable
    • This cable is suitable for surface wiring where there is little risk of mechanical damage
    • Used as a 'Meter Tail', for connecting the CCU/destitution board to the PES(Public Electricity Supply meter
  • What is Single core PVC Insulated sheathed cable's construction
    • PVC Insulated and PVC Sheathing stranded plain copper conductor
    • The insulation colours are normally grey through other colours are available
  • SY Cable (Steel wired Braided Flexible)

    • Instrumentation and control equipment, for tooling machinery production lines, and in flexible applications for free movement without tensile load. Suitable for use in dry, moist and wet rooms
  • The characteristics of, SY Cable (Steel wired Braided Flexible)
    • The galvanised steel wire braid serves as protection against mechanical traverse load and acts as a magnetic screen against interference
    • Sy control cables are not suitable for fixed wiring applications requiring compliance with the regulations set out in BS7671
  • What does a SWA cable consist of
    • Multi-core cable consists of PVC or XPLE insulated conductors made from copper or aluminium with a PVC sheath
    • The next layer is made up of stranded steel wire armour covered with PVC sheath
  • What are SWA cable used for 

    Used in main and sub-main supplies, control circuits, etc. It comes in a variety of shapes and sizes
  • Why clip SWA
    • SWA is heavier than thermoplastic insulated and sheathed
    • Extra care must be made when clipping it
    • Make sure the clipping is not loose otherwise it could bring down a wall, if it was a larger SWA cable
  • SWA Terminations - parts 

    • Shroud
    • Earthing ring
    • Gland body
    • Gland nut
    • There are two types of glands: CW(inside) & BW(outside)
  • Advantages of SWA
    • Good mechanical strength
    • Wide variety of choice of types
    • Can use the armouring as a CPC
  • Disadvantages of SWA
    • Expensive to buy
    • Expensive to install
    • Large and heavy at times
    • Requires special terminations
  • FP200 Cable - Construction
    • Constructed from a solid or stranded copper conductors covered in silicon rubber insulation
    • This cable can come with a range of conductors being 2-19 cores
    • The instillation conductors are covered with a laminated aluminium screen which is bonded to the sheath
    • The sheath is made of robust thermoplastic low smoke zero halogen which is an excellent moisture barrier
  • Advantages of FP200 Cable
    • Fire resistant as to silicon rubber insulation rapidly converts into silicon dioxide, which is a good electrical insulator
    • The cable is easy to handle and terminate
    • No special tools are needed in installing and terminating
    • it has good age resistant insulation
    • Cable bends easily without using tools. It can be used for the instillation of fire systems and emergency lighting systems
  • Disadvantages of FP200 Cable
    • The silicon rubber insulation has not the greatest mechanical strength
    • The bend radius of FP200 should be closely adhered so to avoid damage to the cable
  • MICC(Mineral Insulated Copper covered) Hard wiring cable
    • The inner conductors are made if copper. The outer sheath is also copper, sometimes covered in PVC.
    • The insulation is magnesium oxide, which is a good insulator, it also keeps the conductors in place
    • There are two general types of MI - Light gauge which has a thinner outer sheath than heavy gauge
  • Advantages of MICC
    • Good mechanical strength
    • Wide variety of choice over type, can use the armouring as a CPC
    • Good heat resistant qualities
  • Disadvantages of MICC
    • Expensive to buy
    • Expensive to install
    • Insulation must not get damp
    • Resistant special terminations
  • Thermoplastic flexible cords 3092Y & 3093Y - characteristics
    • Their construction is stranded copper conductors insulated with heat-resisting (HR) PVC and (HR) PVC sheathed
    • These flexible cords are suitable for use with heating appliances