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Machinery and Power

Machinery and machine shops present a variety of electrical safety hazards. When you are working with machinery, you can come into contact with electricity at power panels, electrical circuits and power lines. Guelph Hydro reminds you to be safe around the electricity that powers your machinery.

The surest way to ensure safety around machinery is to stay alert and to follow established safety practices and use common sense.

Proper guarding and clearance around electrical equipment can prevent accidental worker exposure to electrical currents. Common injuries include:

  • Electric shock
  • Burns
  • Falls

These injuries are caused by:

  • Direct contact with electrical energy. When electricity travels through our bodies, it can interfere with the normal electrical signals between the brain and our muscles and cause the heart to stop beating properly, the person to stop breathing, or muscles to spasm.
  • Electricity "arcs" through the air to a person who is grounded, providing the electricity with an alternative route to the ground. These "arc flashes" result in intense heat that cause burns, intense light that can cause blindness, or ignition of other materials.
  • "Arc blasts" cause the same conditions as an arc flash, but are more intense and can also include a strong pressure wave. These pressure waves can damage machinery, throw a person, collapse a lung or rupture ear drums.
  • Thermal burns including flash burns from heat generated by an electric arc, and flame burns from materials that catch on fire from heating or ignition by electrical currents. High voltage contact burns can burn internal tissues while leaving only very small injuries on the outside of the skin.
  • Muscle contractions, or a startle reaction, can cause a person to fall from a ladder, scaffold or aerial bucket. The fall can cause serious injuries.

Prevent Electrical Accidents Around Machinery

  • Guard live electrical components with covers or other permanent barriers to prevent accidental contact by workers and their tools.
  • Get training on electrical safety.
  • Assume electrical equipment and lines are live.
  • Lock and tag out machinery that has been identified as an electricity hazard.
  • Assure that machines remain off while they are shut down for maintenance.
  • Know and observe the company's electrical safety work practices.
  • Install ground fault circuit interrupters (GFCIs) in areas that are wet or damp as they will interrupt the electrical circuit should there be a surge of electricity sufficient to cause death or serious injury.

Electrical equipment can also be locked behind an enclosure, in a room, or at an elevated height. These areas should have restricted access and warnings against unauthorized entry. Permanent markings on electrical equipment with the voltage, current or wattage provide power output information for workers.

Electrical boxes and equipment are best stored in areas free from moisture, chemicals, and excessive temperatures. Electric cabinets with ventilation holes need to remain clear to allow air circulation. Electric parts that ordinarily spark or arc require covers and isolation from combustion sources. Equipment should be securely mounted to the surface that it rests on.

  • Know where the breakers and boxes are located in case of an emergency.
  • Label all circuit breakers and fuse boxes clearly. Each switch should be positively identified as to which machine it is for.
  • Do not use outlets or cords that have exposed wiring.
  • Do not block access to circuit breakers or fuse boxes.
  • Do not touch a person or electrical apparatus in the event of an electrical accident. Always disconnect the current first.
  • Check and adjust all safety devices before each job.
  • Ensure all machines have a start/stop button within easy reach of the operator.
  • Each machine should have only one operator at one time. However, everyone should know how to stop the machine in an emergency.

For more information about safety around machinery, please visit the Canadian Centre for Occupational Health and Safety website at

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