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Welding - Electrical Safety

What should I know about electrical welding?

  • Follow electrical safety procedures to prevent electrical hazards.

Electricity used in welding is available as:

  • single phase, 120 Volts (V) or 240 V; and
  • triple phase 575 V in Canada and 480 V in the USA.

Never connect an American triple phase power supply directly to a Canadian triple phase voltage input. You will destroy the transformer and possibly injure yourself.

Power Supplies

All power supplies must meet the guidelines set by CSA standard C22.1 Canadian Electrical Code, 19th edition, 2009 (in Canada) or ANSI/NFPA 70 (2011) National Electrical Safety Code (in the USA), or by your local electrical utility or other appropriate body.


What are common electrical hazards?

Electric Shock

The human body conducts electricity. Even low currents may cause severe health effects. Spasms, burns, muscle paralysis, or death can result depending on the amount of the current flowing through the body, the route it takes, and the duration of exposure.

Effects of Electrical Shock
EffectDC Current (mA)
Death120+
Ventricular Fibrillation50-120
Paralysis of Diaphragm20-50
Makes hands "clamp-on"16-20
Involuntary Reflexes4-9
Perception1-4

Completion of Circuit through the Body

  • If a person touches a live conductor, current may flow through the body to the ground and cause a shock.
  • Increased electrical contact with the ground increases the risk of shock.
  • Avoid standing in water, on wet surfaces, or working with wet hands or wearing sweaty garments.
  • Small shocks could surprise you and cause you to slip and fall, possibly from a high place.
Completion of an electric circuit through ground

What should I do in case of electric shock?

  • Call for medical help.
  • DO NOT touch the victim with your "bare hands" until he or she is away from the live electrical source.
  • Turn off the power at the fuse box or circuit breaker panel if an appliance or electrical equipment is the electrical source or, if you can do it safely, turn off the appliance or electrical equipment and unplug it. Just turning off the equipment is not sufficient.
  • If the electricity cannot be turned off and the victim is still in contact with the electrical source, decide if you must move the victim or push the wire away from the victim (call for emergency help if the wire is a high voltage power line).
  • Insulate yourself if you must move a victim away from a live contact - wear dry gloves or cover your hands with cloth and stand on dry insulating material like cardboard, wood or clothes. Ensure you have good footing and will not slip or fall when trying to move the victim.
  • Use a dry piece of wood, broom or other dry, insulating object or material to move the wire or power source away from the victim or push the victim off the live electrical source.
  • Do not move the victim if there is a possibility of neck or spinal injuries (from a fall, for example) unless it is absolutely necessary.
  • Give artificial respiration if the victim is not breathing.
  • Give CPR if the victim's heart has stopped (only if you are trained in CPR).
  • Cover burns with a sterile dressing. There may be a burn where the power source touched the victim and in the area where the electricity left the body (to ground). On the surface electrical burns may not look serious but deeper in the tissue the burn can be severe.
  • Keep the victim comfortable, warm and at rest, and monitor breathing.

Document last updated on October 12, 2010

Disclaimer

Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.