Method for Installation of Conceal & Surface Conduits (Part-1)

(A) Purpose: .

  • This method explains the sequence of activity for safely installation of PVC / GI Conduits and it’s accessories in the concrete slabs / columns, in block works and on Surface as per the standard Practice and Code.

(B) Storage & Material Handling:.

  • The storage area must be free from dust and Water leakages / seepages.
  • Manufacturer recommendation shall always be followed in loading/unloading and storing of Material.
  • Material and its accessories shall be unloaded handle with care in designated area of the Store (Do not directly drop to Ground) to avoid any damages.
  • Materials shall be stored in a dry place which is free from water or from weather effects and protection should be given to the material by means of covering the material with Tarpaulin sheet.
  • The Material will be stacked / unload in the site store on a proper stand on wooden loft on a flat surface at a sufficient height from Ground.
  • If Material are dispatch in packs or pallets, each pack or pallet shall be lifted individually with suitable lifting equipment.
  • The material shall be transported / Shifted in their original packing to Site location.
  • The Material should be visually inspected for damage, which may have occurred during transport.
  • If the Material is found defective it shall not be installed and the cable shall be returned to the supplier for replacement.

(C) Inspection of Materials:.

  • Check The Material according to its Type, Size, Make
  • Visual inspection:
  • Type and Make of Conduit and Accessories Material
  • Length , Width and thickness of PVC / GI / MS Conduit Material and Accessories
  • Physical Damages Inspection:
  • Damage on Material and it’s Accessories
  • In case of any damages observed during inspection, the concern report will be issued and Material shall be returned to the supplier for replacement.

(D) Concealed Conduit in Slab / Column:.

  1. Shifting Material to Working Area:

  • PVC Conduit and its accessories shall be carefully unloaded or shifted to the site by using Crane/Hydra or by sufficient manpower and moved to a defined installation location.
  • Remove the packing and ensure that the material is free from transportation damages
  • Check and ensure that approved drawings, the correct size and type of Conduit & its accessories are ready for installation.
  • Ensure that Conduit and its accessories received from site store for the installation are free of rusty parts and damages.
  1. Marking Electrical Point / Wall Conduit Drop on Slab:

  • Ensure that the civil activities are finished I,e Slab Shuttering Work and Steel Work and Site is ready for Electrical Work on Slab.
  • After completing the first layer of steel, start marking of Ceiling Points and Wall Drop Points on Slab as per approved Site Drawings.
  • Mark first the wall location for lower floor in slab as per latest Architecture layout so that it will be easy to locate the drops for switch, Wall Light Points and any other drops required for electrical system.
  • Mark the opening size in Slab or in Beam i.e window, door and shaft as per approved electrical drawing to avoid passing wall conduit drop on that area.
  • Mark the Electrical points on the slab, Wall Conduit Drop in Beam as per approved Electrical Shop Drawing.
  • Make sure that marking of Wall conduit drop is placed in center of wall, it is not out from wall or not move to any face of wall.
  • For initially use marker / Chalk for making location of electrical point on slab and wall drop after that apply oil paint on that location before conducting work so after de shuttering ,the JB or conduit drop is easily visible on slab or on beam.
  1. Installation of Junction Box and Conduit:

  • Chalk will be used to mark the PVC conduit route. Make sure that size of conduit is as per approved Electrical Shop Drawing.
  • Ceiling Conduits shall be laid on the prepared shuttering work of the ceiling slab before concrete is poured. The conduits, boxes, accessories, joints, etc. shall be laid along with the conduits.
  • Use Deep Junction Box for surface mounted lighting Fixtures and for Cable Pulling.
  • Use long radius bend or make as per site requirement by using PVC Conduit bending spring.
  • Joints between PVC conduit + fittings shall be made with suitable adhesive.
  • Try to avoid the overlapping of conduits and keep some distance between the conduits for low current and power/Lights.
  • To maintain at least 20mm spacing gap between PVC conduits running in parallel. To allow adequate / sufficient space between formwork and conduit so that embedded conduit is fully covered by concrete and will not result in any honeycomb or structural defects in the future.
  • Concealed conduits in slabs shall be brought out as vertical drops in beams, wherever such drops are required.  All vertical conduits in beams shall be left protecting from the bottom of the beam. All such ends of conduits protecting from bottom of beams shall be provided with couplings to receive extension.
  1. Fixing of Conduit & Accessories:

  • The conduits shall be adequately fixed to prevent excessive movement and damage during the pouring and setting of concrete and shall be protected from mechanical damage.
  • For Double layer of rebar, PVC conduits shall be secured to the bottom of Top layer rebar and for Single Layer rebar, PVC Conduit should be secure at top of rebar with binding Steel Wire.
  • After completing the work, tight the conduits with binding wire .PVC Conduit should be bound at intervals of not more than 1 meters by binding short lengths of steel wire, of not less than 2mm diameter twisted around the conduit and reinforcing steel. Additional Steel bonding Wire also provide near each PVC Conduit Coupler, PVC Bends and near Junction Box
  • Check there is no damage in PVC Conduit and it’s accessories before concrete is poured.
  • The open ends of Conduit should be protected during concreting by caps or plugs to prevent the ingress of building material.
  • All Junction Box, Fan Box should be protected during concreting by filling thermo coal Sheets to prevent the ingress of building material.
  • Ensure conduits are not concealed until works has been inspected and approved.
  • Before the concrete pouring the PVC conduit installation to be inspected and approved by consultant/client/contractor.
  • During concrete pouring, keep electricians for taking care of conduit to avoid any damage by others or dislocation of joints.

(E) Recess / Concealed Conducting in Wall.

  • Ensure that bricks / Block masonry work is complete and Site is given for electrical works.
  • Check the required reference markings are available for FFL (finished floor levels).
  • All required materials shall be shifted and stored under safe custody near workplace on daily basis as per planned quantity.
  • In the case of building under construction, conduit shall be buried in the wall before plastering and shall be finished neatly after erection of conduit.
  • In case of exposed brick/rubble masonry work, special care shall be taken to fix the conduit and accessories in position along with the building work.
  1. Marking of Switch Box and Light Points:

  • Mark the location of switch/socket and conduit route on proper height based on approved shop drawing.
  • No conduit smaller than 20mm in diameter or larger than 32mm diameter shall be used.
  • Mark the location of Switch Box, DB, and Junction Box for Light Point on the wall from FFL.
  1. Wall Chasing:

  • After marking of conduit and Switch Box location, Wall chasing shall be done using wall cutting machine.
  • Hammer and chisel will be used on the chased portion to get uniform depth of 50 mm or as per standard specifications.
  • All chases, grooves shall be neatly made to proper dimensions to accommodate the required number and size of conduits and staples. The outlet boxes, point control boxes, inspection and draw boxes shall be fixed as an when conduit is being laid. The recessing of conduits in walls shall be so arranged as to allow at least 12 mm plaster over the same. 
  • The chase in the wall shall be neatly made and of ample dimensions to permit the conduit to be fixed in the manner desired.
  • Wherever the length of conduit run is more than 10 meters, then circular junction box shall be provided to permit periodical inspection and of facilitate replacement of wires, if necessary. These shall be mounted flush with the wall.
  • In place where the conduit is crossing at different ceiling height, uniform bending shall be done. The bending of conduit shall be done using proper bending springs.
  • Conduits will be cleaned with a round file from inside and outside of the pipe after cutting.
  • Connect the conduit by using PVC solvent with an adaptor to the junction box. Apply PVC Solvent cement on the portion of conduit entering into coupler wherever applicable.
  • PVC Conduits shall be duly fixed by using a hook or Nail. Distance of GI hook / Nail shall be maintained at 500 mm at intervals.
  • Embedded back box, JB shall be protected by covering with brown tape filled with jute/gunny bag.
  1. Installation of the Box / Enclosure:

  • At Planning and Designing Level, always Select DB Wall block work thickness should be 200 mm instead of 100 mm for easy DB installation.
  • For Properly Installation of DB and Switch Box, locate plaster level points near DB or Switch Board.
  • The mounted height of the Switch Board is generally 1200mm (Bottom of Switch Box) in all rooms ,300 mm near Bed and for DB it is generally 1800mm (bottom of panel) or as per approved Drawings.
  • Ensure the box size and accordingly cut a bit larger size of box in marked place of block wall with sufficient depth.
  • Fix the GI Metal box of appropriate size and level with the help of spirit level.
  • Installed the Switch Box and DB with the use of cement mortar around the box. Make sure that it is flush with finished plaster level.

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  • The bottom portion of box should match the marked level as per consultant approved height for switch/ socket and/or as per local applicable wiring regulation requirements.
  • Apply cement filler to fix the box properly and leave for setting, insert the required lengths of conduits on their paths and don’t connect with boxes until next day.
  • Next day, after setting of box connect the dropped conduits for switch/socket to the box.
  • The switch box shall be flush with the plaster. The height of the switch boxes shall be as indicated in the drawings. The switch boxes should be sufficient depth to give minimum 20 mm plaster cover to conduits embedded.
  • Distribution board interiors will not be installed in cabinets until all conduits connections to the cabinet have been completed.
  • Trim for flush mounted cabinets will be installed in plaster frame, flushed with furnished wall.

About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

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