SAFE USE OF ELECTRICAL POWER IN CONSTRUCTION

Objective:-

To identify the electrical hazards and eliminate these for safe use of electrical power in construction sites.

Safe Use of Electrical Power in Construction:-

Major effects of electrical hazards

  1. Shock

  Up to 10 ma            –       No shock

            15 ma          –       Feeble shock

            30 ma          –       Severe shock

         > 30 ma          –       Fatal shock

Electrical Shock Causative Factors:-

  • Exposed joints.
  • Exposed terminals.
  • Unguarded substations.
  • Metallic parts without earthing.
  • Plugs without plug tops.
  • Neutral control.
  • Poor insulated non standard cables, switches,breakers,isolators,plugs, plug tops etc.
  • Non usage of discharge rod.
  • Combining power cables with welding cables.

Control Measures to Avert Electrical Shock:-

Earthing to metallic parts

(Motors, Generators, Transformers, Welding M/Cs,Dist.Boards, Flood Lights,Driers,Mixers,Vibrators, Drilling Machines and Grinding Machines.)

  • Provide rubber mats near Switches,Breakers,Isolators,Electrical Panel etc.,
  • Wear Rubber Sole Shoes.
  • Wear Rubber Hand Gloves (18” Electrical Grade -IS :4770-1991).Cable Routing
  • Over Head above 7’.
  • Underground Tray / Conduit.
  • Lay Power Cable and Welding Cable Separately.
  • Use Double insulated Standard Cables.

Cable Joints:-

  • Avoid jointing of cables as far as possible.
  • Use cable jointing kits for higher capacity.

Colour code of the cable

   Phases – Red, Yellow & Blue

  Neutral – Black

  Earth –    Green

  • Use 24 v lamp in confined space and concreting areas
  • Use non-conductive ladders for electrical jobs/close to Busbars.
  • Use fuse pullers.
  • Use insulated hand tools
  • Use cable route tracer in excavation work in existing factories and roads in cities.
  • Use ELCB/RCCB for construction power/in the Distribution boards
  • Use discharge rods for Overhead lines.
  • Use permit to work.



 Burns:-

  • Causative factors
  1. Flash over due to short circuit between        

Phase to Phase– Phase to Earth -Phase to Neutral         

  • Control measures
  1.   Connect MCB/RCCB and correct rating fuse links

     2.Avoid using non standard/poor quality cables.

  • Do not use single bulb for test lamp use two bulbs of 250 v in series for checking 415 v and 250 v.
  • Avoid multi socket plugs.
  • Do preventive maintenance.
  • Take a clearance from overhead power lines.

Minimum Safe Clearance values for various Voltage levels:-

 

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