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
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.
- 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.
- Causative factors
- Flash over due to short circuit between
Phase to Phase– Phase to Earth -Phase to Neutral
- Control measures
- 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:-