EIM 1 PART 1

• City of Good Character
• DISCIPLINE • GOOD TASTE • EXCELLENCE
• Rigid Nonmetallic Conduit
• Rigid Nonmetallic Conduit (RNC)


  Nonmetallic raceway of circular cross section, with associated couplings, connectors, and fittings for installation of electrical conductors and cables
• RNC

  • Lightweight
  • Significantly cheaper than metallic conduits
  • Resistant to moisture and chemical atmosphere
  • Flame retardant or not easily burned
  • Resistant to impact and crushing
  • Do not easily get out of shape by the heat
• Schedule 40 RNC

  Thin wall, permitted underground (direct burial or encased in concrete) and aboveground (indoors and outdoors exposed to sunlight) where not subject to physical damage
• Schedule 80 RNC

  Thick wall, permitted underground (direct burial or encased in concrete) and above ground (indoors and outdoors in sunlight) where subject to physical damage
• Conditions where RNC is permitted to be used


  • Concealed in walls, floors, and ceilings
  • In locations subject to severe corrosive influences
  • In cinder fills
  • In wet locations
  • In dry and damp locations
  • In exposed work not subject to physical damage
  • For underground installation
• Conditions where RNC shall not be used

  • Classified hazardous locations
  • Support of fixtures
  • Where subject to physical damage
  • Where subject to ambient temperature higher than 50°C
  • For conductors or cables operating at a temperature higher than the RNC operating temperature rating
  • In theaters and similar locations
• RNC cannot be used as equipment grounding since it is nonmetallic
• Maximum number of conductors in RNC

  Determined by a table in the Philippine Electrical Code
• Cutting PVC conduits

  1. Use fine-tooth saw, hacksaw, or PVC pipe cutter

  2. Trim inside and outside the cut edges to remove rough edges
• Joining PVC conduits

  Apply PVC pipe cement/solvent between the ends of the conduits to be joined
• Securing and supporting PVC conduits


  1. Use approved fittings such as conduit strap or clamps

  2. Support within 900mm or 3ft between electrical boxes

  3. Use PVC fittings and accessories to secure the pipe in electrical boxes
• Bending PVC conduits

  1. Apply heat from a heat box, blowtorch, or heat gun

  2. Bend to desired angle

  3. Harden by soaking in cold or lukewarm water or dampening with a wet rag
• Minimum radius of a 90-degree bend for RNC is determined by a table
• Field bends are bends made to fit the needed angle of the actual installation
• The total bends in a run of RNC shall not exceed 360 degrees
• Bending


  The process of shaping rigid nonmetallic conduit (RNC) to a desired angle
• Tools for bending RNC

  • Blowtorch (when electricity is not available)
  • Heat gun (more convenient than blowtorch when electricity is available)
• Bending RNC


  1. Pre-heat until desired softness is obtained

  2. Bend little by little to desired angle

  3. Harden by soaking in cold/lukewarm water or dampening with wet rag
• Minimum radius of 90-degree bend


  Determined by table based on size of conduit
• Types of PVC bends

  • Elbow
  • Offset bend
  • Round saddle bend
  • Square saddle bend
• Field bends


  Bends made to fit the needed angle of the actual installation, such as to avoid obstacles
• Total bends along a conduit run shall not be more than the equivalent of four quarter bends (360° total) between pull points
• Rigid nonmetallic conduit (RNC) is a nonmetallic raceway of circular cross section which are manufactured to be resistant to moisture and chemical atmosphere
• Thick wall RNC


  Easier to bend
• RNC


  Also known as rigid PVC or PVC pipe, made of polyvinyl chloride
• Conduit strap


  Accessory necessary for securing and supporting RNC
• RNC is flame retardant or not easily burned, resistant to impact and crushing, and does not easily get out of shape by heat
• RNC cannot be used as part of fixtures but can be installed on concealed walls, floors or ceilings
• If equipment grounding is required, a separate conductor shall be installed in a nonmetallic raceway
• PVC pipe cement/solvent


  Applied between the ends of conduits to be joined to make a strong and watertight joint