In addition to the damage referred to above: External burns by temperature, external burns by projection of molten metal, external burns by U.V. (cancers), burns of the lungs by breathing of burning and/or toxic gases, eye loss by UV (electric arc at 6000°C in the blue/U.V. spectrum), fall due to electric shock, fire - explosion, poisoning by toxic fumes, eye loss by UV (electric arc at 6000°C in the blue/U.V. spectrum), fall due to electric shock, fire - explosion, poisoning by toxic fumes, wounds caused by mechanical projection
The intensity passing through the human body depends on: the voltage applied and the resistance of the path In 220 V, dry skin, the resistance of the human body is about 2500 ohms. Direct contact between the phase and the neutral, for example, therefore causes a current of 90 mA to pass through. U = R x I so I = U/R = 220/2500 = 90 mA. For phase-ground contact (ground), the resistance of the shoes is added. (Hence the interest of stools and rugs).
Direct contact:
Direct contact is the contact of a person with the active parts of energized equipment.
An active part can be an energy conductor or even a neutral conductor.
Indirect contact is the contact of a person with metal masses that are accidentally energized.
A mass is a metal part that is normally isolated from the active parts and grounded.
Electrification
- Does not cause death
- Muscle tetanization of the respiratory muscles
- Start of asphyxiation
- Burns: severe burns (to the 3rd degree) visible at the level of entry and exit of the current. Muscle masses and vasculo-nerve pathways are very exposed (renal and metabolic risk of rhabdomyolysis), burns by electric flash (lightning) dangerous for the eyes, burns by electric arc: for very high voltage currents, the air becomes a conductor and the person is electrified without touching the electrical conductor.
Electrocution
- Causes death unless treated promptly
- Respiratory arrest
- Ventricular fibrillation (disturbance of heart cells that start to shake)
- Cardiac arrest (the heart no longer assumes its role as a pump and can no longer return blood to the body).
In alternating current (multiply the values by 1.5 in direct current):
Current - 0.0005 A
220V power - 0.1 W — Quartz watch
Effects - Perception Threshold
Current - 0.005 A
220V power - 1 W — Mobile phone
Effects - Touch-let go
Current - 0.010 A
220V power - 2 W — Alarm clock radio
Effects - Threshold for not letting go Muscle contraction
Current - 0.030 A
220V power - 7 W — low consumption bulb
Effects - Blue syncope Respiratory paralysis
Current - 0.075 A
220V power - 16 W — Computer speaker
Effects - White Syncope Cardiac Fibrillation - Cardiac Arrest
Current - 0.100 A
220V power - 22 W — Live Box
Effects - Same + internal burn
Current - 1 A
220V - 220 W power — halogen living room lamp
Effects - Same + Chemical decomposition of blood Irreversible Destruction of the nervous system Certain death
Current - 5 A
Power in 220V - 1000 W - hair dryer
(source: INRS)
The resistance of the human body varies according to:
- Tension
- From its humidity
It also varies according to:
- The contact surface
- The condition of the skin
- Fatigue, health, age
(source: INRS)
Dry skin at 50V: 4000 ohm.
I=U/R = 50/4000 = 12mA (threshold of not let go)
The damage caused by the passage of an electric current in the body also depends on the electrification time.
AC1: Non-perception
AC2: Touch-let go
AC3: Muscle tension — not let go
AC3-4: Respiratory paralysis — Ventricular fibrillation
AC4: Internal burn - Irreversible chemical decomposition of blood - Destruction of the nervous system - Certain death
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