Properties, applications and limitations of wiring systems

• 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