Essential Electrical Safety Standards and Current Hazard Levels

Factors Affecting Electrical Shock Risk

Risk varies with age, sex, health status, and other factors. For example, women and children are often more vulnerable than men. This vulnerability is frequently attributed to differences in skin type and resistance.

Effects of Electric Current on the Human Body

The severity of an electrical shock depends heavily on the current intensity (measured in milliamperes, mA):

• 1 to 2 mA: Tingling sensation.
• 9 mA: Muscle contraction; the person can usually let go.
• 10 mA: Bearable pain threshold.
• 15 mA: Tetanization (involuntary muscle contraction). Stiff arm.
• 25 mA: Tetanization of chest muscles, potentially leading to asphyxia if prolonged.
• 50 mA: Ventricular fibrillation of the heart (requires immediate artificial respiration and heart massage).
• 1 A (1000 mA): Certain death if contact is sustained.

Electrical Fire Risks

Fires in electrical installations are typically caused by:

• Overheating of facilities due to higher consumption or poor contacts.
• Short circuits caused by direct contact between phase and neutral conductors.

Voltage Risk for Birds on Wires

When birds perch on aerial conductors, they do not suffer any electrical discharge because they are not subjected to a differential potential (voltage difference) across their body.

Safety Voltage Limits (SELV/PELV)

Maximum safety voltage limits vary depending on the environment:

• Dry Locations: Maximum safety voltage 50 Volts.
• Wet Locations: Maximum safety voltage 24 Volts.
• Submerged Locations: Maximum safety voltage 12 Volts.

Installation Protection Devices

Installations must be protected against overheating and short circuits by a Main Circuit Breaker (ICPM) and the assembly of independent circuits, which are often protected by individual circuit breakers (MCBs or PIAs).

Golden Rules of Electrical Safety

1. Never inspect an installation or perform work on it without first disconnecting the energy supply.
2. Ensure nobody can reconnect the power. It is best practice to put up a warning sign or remove the fuses.
3. Before working, use a tester to verify the line is de-energized (zero voltage).
4. Always use the correct tools for the job. Do not use damaged, worn, or outdated equipment.
5. The protective conductor (ground wire) cannot be disconnected, removed, or used for other purposes.
6. Before working on an electrical device, disconnect it. After completing the repair and before connecting the unit to the outlet, thoroughly check the work done.
7. Before inserting a fuse, ensure its amperage rating is correct for the circuit it protects.
8. When working on an installation, it is advisable to wear shoes with rubber soles.

First Aid for Electrocution Victims

In the event of an electrocution incident, follow these steps:

1. As the first step, disconnect the power supply.
2. Separate the affected person from the contact point, without touching them. Pull on their clothes or use a cane or other non-metallic element.
3. If breathing stops, perform rescue breathing (CPR).
4. Do not cover the victim with blankets or give them alcohol.
5. Rub their body with your hands to activate blood circulation. This must be continued until medical help arrives.
6. In no case should you lose your calm. Remaining calm allows you to help the electrocuted person most efficiently and avoid secondary accidents.
7. Immediate medical help is required if the case is serious.

Calculating the Appropriate Cable Section

1. Calculate the rated current that will pass through the conductor.
2. Consult the appropriate cable sizing table for the specific application.