Generally, welding and thermal cutting operations are not hazardous but complete safety is necessary for welding because electric current or high voltage current is used in it. The hazards which are more or less peculiar to welding are:
Electric Shock
Arc radiation
Fumes and dust Compressed Gases
Fire and explosions
Electric Shock
Electric shock may occur in welding if current happens to pass through the welder body. The magnitude of the current will depend upon the resistance offered by the body. A current of 0.1 A or above, be it ac. or d c. is taken to be lethal to humans. Since the maximum human body resistance is 600 ohm, the lethal current will be provided by the voltage of just 60 V (V = ± R).
Electric shock results in many accidents the occur during welding. Therefore necessary precautions must be taken to minimize electric risk. This can best be done by ensuring the props insulation of cables, and reliable earthing o welding equipment. The grounding circuit sanitary sewers and water pipes or metallic structures of buildings and process equipment should never be used as earth or return fo welding circuit.
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