Electrical+Safety

Are you risking electric shock when you weld?
 * Welding Safety **

Although manual metal arc welding can be performed perfectly safely, there is a substantial risk of electric shock. It is obvious that poorly maintained or badly connected equipment may be extremely hazardous. What is not so well known is that an electric shock from the output terminals of the welding machine can cause death or serious injury.

Manual metal arc welding and arc-air gouging are particularly risky because the electrode is changed frequently while the electrode holder is electrically live. There is a high risk that the welder can receive a shock by simultaneously touching the electrode and work piece. Fuses or earth leakage contact breakers do not protect the welder from such a hazard. Many welders have suffered such shocks and have only experienced an unpleasant tingle, but muscle spasms from even a mild shock may lead to a fall from a height or injury by striking. Death by electrocution has occurred in such extreme circumstances.

Factors which affect the severity of the shock are: The no-load or open circuitry voltage (OCV) of the welding machine; whether the machine supplies alternating or direct current (A.C. is 2 to 3 times more dangerous than D.C.) The pressure of moisture from rain, perspiration or other source; How well the victim is insulated from the electrode and the work piece; Which parts of the body are in contact with the work and the electrode. Current flow between the left hand and the torso is the most dangerous; the susceptibility of the victim to shock, which is dependent on health and other factors.

Processes such as GMAW (MIG) do not require frequent electrode changes and are activated by a contact switch at the torch. They therefore carry less risk.

To avoid electric shock: Avoid bare skin contact with the electrode; and either prevent contact with the work piece, or use a welding machine which is safe for electrically hazardous environments, or which has a voltage limiting device fitted. An environment is considered electrically hazardous whenever the welder has to work in physical contact with the work piece, particularly in a cramped (kneeling, sitting or lying) position. The environment is not electrically hazardous if the welder is electrically insulated from the work piece, but in many cases this may be impossible or uneconomical. Examples include shipbuilding work, inside vessels, pipes and structural components. The electrically hazardous environment does not need to be a confined space.
 * ** Environment ** || ** Maximum OCV **


 * direct current ** || ** Maximum OCV **


 * alternating current ** ||
 * Non electrically hazardous || 113 volts || 113 volts peak or 80 volts rms ||
 * Electrically hazardous (dry) || 113 volts || 68 volts peak or 48 volts rms ||
 * Electrically hazardous (wet) || 35 volts || 35 volts peaks or 25 volts rms ||

An electrically hazardous environment is compounded in wet, damp or hot locations where moisture or perspiration considerably reduces the electrical resistance of the human body and the insulating properties of accessories. The precautions described below can often be taken to the limit risk. If there is difficulty in keeping dry, a voltage limiting device should be used to limit the OCV to a maximum of 25 volts, or the power should be controlled by a contactor switch. Such damp environments include: underwater, in the splash zone, while standing in water, in rain, welding in a hot or humid area when it is impossible to avoid accumulation of perspiration or condensation, and in mines.
 * 1) All persons who work near or assist in welding operations should be familiar with rescue procedures. The following precautions are required to protect from electric shock:
 * 2) When a workplace hazard assessment is conducted, ensure the risk of such electric shock is considered and appropriate measures are taken to minimize the risk.
 * 3) The use of dry, hole free welding gloves on both hands while welding, particularly when changing electrodes should be compulsory and be a written safety policy.
 * 4) Remove stub ends immediately after welding; do not leave an electrode holder with a stub end in it.
 * 5) Turn off the power at end of each shift or when taking a break. Do not drag live leads to the work.
 * 6) If possible make the environment electrically safe by using dry, fire resisting insulation. Wooden duckboards, leather covered cushions, leather aprons, leather jackets; heat-resisting blankets should be used to cover those parts of the work piece which the welder may contact. It is not possible to provide such insulation, or to keep it dry, the environment must be considered electrically hazardous, and equipment should be safe for such environments.
 * 7) In hot conditions the risk of electrocution is increased because of clothing and equipment being soaked in perspiration. The risk is far worse in closed environments, such as tanks or vessels, particularly when these are exposed to the sun's heat. Take frequent rest periods, during which time dry off equipment and clothing. Frequently change or alternate gloves and protective clothing to avoid perspiration accumulating. Ventilate or if possible air-condition the work air. Ventilation will help dry perspiration and cool the body. Cool the face with an air mask. If clothing (including gloves) becomes soaked with perspiration, it must be changed.
 * 8) If it is not possible to keep it dry, the environment must be considered extremely dangerous. Either a voltage limited welding power source should be used, or a contractor switch on the torch should control the power.