Electrical Safety
How electricity injures through shock, burns, falls and fire, what causes electrical accidents at work, and the protective measures, work practices, PPE and first aid that reduce the risk.
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7.1 The Basics
An electric circuit is the complete path of the current. It has a source of electricity, a conductor and a load, such as a lamp, tool or heater. Electric shock happens when the body becomes part of the circuit.
| Term | Meaning |
|---|---|
| Current | The movement of electricity, measured in amperes (amps). |
| Volts | The unit of electrical force. |
| Resistance | Restriction to the flow of electricity. |
| Conductor | A material, such as metal, that lets electricity flow easily. |
| Insulator | A material, such as glass, porcelain, plastic or dry wood, that resists the flow of electricity. |
| Grounding | A conductive connection to the earth, at zero volts, that acts as a protective measure. |
| GFCI | A ground fault circuit interrupter. It cuts off the flow of electricity when it senses a loss of proper grounding or a very small leak, and so lowers the chance of injury or death. |
| Wire gauge | A measure of wire size. In the American wire gauge, smaller numbers are thicker wires. |
7.2 Accidents and Injuries
When current enters the body it can cause shock, burns, falls and fires. The main causes of electrical accidents at work are:
- defective or improper tools
- use of tools or equipment very close to energised parts
- overloading outlets with too many appliances
- repairing tools or equipment while the power is on
- working near power lines, especially at height
Metal surfaces and parts can also become energised if there is a break in the insulation of the wiring, so touching a machine can cause a shock.
Burns
Burns are the most common injuries from electrical incidents. There are three types:
- Electrical burns. Current flowing through the body can damage tissue and the heart.
- Arc and flash burns. The high temperature of an electrical arc or explosion near the body causes these.
- Thermal contact burns. Skin touches overheated equipment, or clothing catches fire.
Indirect injuries
A shock can make a person fall. A worker who is shocked at a height may be seriously hurt or killed by the fall rather than by the electricity.
7.3 Hazards and Protection
Electrical hazards come from inadequate or damaged wiring, exposed electrical parts, wires with bad insulation, ungrounded systems and tools, overloaded circuits, damaged power tools and equipment, and power lines.
Protective measures
- Proper grounding of systems and tools.
- Fuses and circuit breakers, which break an overloaded circuit.
- GFCIs, particularly in damp places and for portable tools.
- Guarding live parts, so that no one can touch them by accident.
- Double insulated tools, which are built so that the user is isolated from live parts.
Safe work practices
- Keep work places and walkways clear of electrical cords.
- Use barriers and guards to prevent injury from exposed energised equipment.
- Plan the work, use PPE and post warnings.
- Isolate equipment from its energy sources with lockout/tagout before work on it.
- Do not repair electrical equipment unless you are qualified.
Essentials of safe work
- Plan every job.
- Use the right tools for the job.
- Follow procedures, drawings, diagrams and other documents.
- Isolate equipment from energy sources, with lockout/tagout.
- Be trained to do the job properly.
- Use suitable PPE.
7.4 Personal Protective Equipment
PPE protects the body from electrical hazards. Wear a non-conductive hard hat, footwear that protects the feet, and rubber insulating gloves, hoods, sleeves, blankets and matting where the work calls for them. Keep ladders non-conductive near electrical work.
7.5 First Aid
- Do not touch a person who is still in contact with a live source. Turn off the power first, or move the person away with a dry non-conductive object if you cannot switch it off at once and you can do so safely. A rescuer who touches the victim can be shocked too.
- Call emergency services at once for anything beyond a minor injury, since an electric shock can cause heart problems that appear later.
- When a person has been burned, cool the burn with water or saline until the skin is back to normal temperature.
- Avoid moving the victim, who may have broken bones or internal injuries.
- Give first aid as appropriate, including CPR if you are trained and the person is not breathing, and keep the victim as comfortable as you can.
A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.