Electrical Hazards and Controls

Welding machines are generally grounded through their electrical connections via a third grounding wire. Mobile engine-driven generator welding units should be grounded by connecting a cable to a ground stud on the machine to a metal stake driven into the ground. Always follow the manufacturer's instructions for properly grounding the particular model that will be used.

Auxiliary receptacles on welding machines may or may not be ground-fault circuit-interrupter (GFCI) protected. GFCI adapters, or "pigtails" should be used in wet or damp locations. Tools, extension cords, or equipment plugged into these receptacles must be grounded or double insulated.

When grounding the workpiece to the welding table, make sure that the table is also grounded (typically a cable from the table leg to the building structure). Avoid grounding to a building structure that is a great distance from the weld. Never use pipelines carrying flammable liquids, and never use electrical conduit as a ground.

• Cables should be inspected prior to use for cuts, burns, or damage to the insulation and uniform flexibility throughout.
• Inflexible sections of the cable can indicate fusing of the copper filaments probably caused by a current leak. 
• Cables with splices within ten feet of the electrode holder shall not be used. 
• Connections should be tight, clean, and dry. 
• Do not use worn, damaged, undersized, or poorly spliced cables.
• Check lugs and fittings on the equipment to ensure they are tight.

• Never use electrode holders with missing insulators. 
• Do not dip the holder in water to cool it. 
• Do not lay the holder on conductive surfaces.
• Do not touch holders connected to two welding machines at the same time.
• Do not touch people with the holder or electrode.

Electric shock from welding and cutting equipment is significant enough to result in death, severe burns, or secondary injury from falls. The electrode and work circuit is electrically energized when the output is "on". The input power circuit and machine internal circuits are also electrically energized when the power is "on". When stick welding, the metal jaws, screws on the holder, and the electrode are all electrically energized. When wire welding, the wire, wire reel, drive rolls, and all other metal parts touching the wire are electrically energized.

Some situations can increase the risk of electrical shock during welding/cutting. Such electrically hazardous conditions include welding/cutting in damp locations, while wearing wet clothing, on metal structures, such as floors, gratings, or scaffolds, or in cramped positions, such as sitting, kneeling, or lying down. 

Always review and follow the manufacturer's instructions for the specific welding equipment used.

Primary "input" voltage shock (220-480 volts) - For example, touching a lead inside the welder with the power to the welder "on" while part of your body or a hand is on the welder case or other grounded metal. Remember, turning the welder power switch "off" does not turn the power off inside the welder! To turn the power inside of the welder "off", the input power cord must be unplugged or the power disconnect switch turned off. You should never remove fixed panels from the welder. Electric shock hazards associated with arc welding may be divided into two categories:

• Secondary "output" voltage shock (20-100 volts) - For example, touching a part of the electrode circuit such as a bare spot on the electrode cable at the same time another part of your body is touching the metal upon which you're welding (i.e. the workpiece). To receive a shock, your body must touch both sides of the welding circuit - the electrode and the work (or welding ground) - at the same time. Remember, the voltage at the electrode is highest when you are not welding (i.e. open circuit voltage). Safe work practices and habits, such as keeping everything as dry as possible, maintaining and using equipment in good condition, and preventing accidental contact with equipment when not in use.