It can happen to experienced engineers too. Stay carefull.

It can happen to experienced engineers too. Stay carefull.

Injuries caused by electric shocks

The effect of electricity on the body depends on the amount of current and the length of time the body is exposed to it. The higher the current, the less time a human can survive the exposure.

The path of electricity through the body is also critical.

For example, current passing through the heart or brain is more life-threatening than current passing through the fingers. It takes approximately 1,000 milliamps (1 amp) of current to light a 100 watt bulb. Here are the effects you can expect from just a fraction of that current for a few seconds.

The figures illustrate that a small amount of current for a few seconds or more can be fatal (see figure 1).

It is the amperage that kills or injures. But the voltage, which pushes the current through the body, is also important.

When a victim is exposed to household voltages, he or she may suffer a muscle spasm and may be locked on to the electrical source until the circuit is turned off, or until the victim is dragged clear, often by the weight of his or her body falling clear of the contact.

Relatively long periods of contact with low voltage are the cause of many electrical fatalities in the home or at work.

Amount of CurrentEffect on a Human
 1 to 4 milliamps Can just be felt
 5 to 9 milliamps Increasing pain
 10 to 20 milliamps Cannot let go
 21 to 50 milliamps Severe pain, muscular contractions
 Above 50 milliamps May be fatal, destruction of tissue (burning), stop breathing

At very high voltages (on power lines, for example), the victim is often quickly blasted clear of the circuit. This results in less internal damage, such as heart failure, but terrible surface burns on the body at the entrance and exit of the current.

Note:

All electrical shock and burn accident victims should receive prompt standard first aid treatment, followed by professional medical attention, regardless of the severity.

Electric shock current situations

Figure 2 – Electric shock current situations


Effects on the body

Any victim of electrical shock should be examined for the following effects on the body:

  1. Contraction of chest muscles, causing breathing difficulty and unconsciousness.
  2. Temporary paralysis of the respiratory organs resulting in failure to breathe.
  3. Ventricular fibrillation of the heart (mainly from lower voltages).
  4. Burns to tissue at the entrance and exit points (mainly from higher voltages). 5. Fractures caused by muscle spasm.

Effects of electric shock effects on the body

Figure 3 – Effects of electric shock effects on the body


Notes:

  • Electricity always seeks the easiest path to ground. If you touch an energized wire or another energized object and the ground at the same time, you may get killed or injured.
  • It must be kept in mind that before any treatment can be given to the victim, the danger must be removed. In some cases, the circuit can be turned off. In other cases, it cannot.

How to Cope with Electrical Injuries

Situation 1:

Cardiac arrest. Heart action may stop if control centres of the heart are paralyzed.

Action:

Start cardiopulmonary resuscitation immediately.

Situation 2:

Ventricular fibrillation. This condition is more likely to be caused by a shock of relatively low voltage. The heart muscles lose the rhythm and throw the heart into spasms.

Action:

Start cardiopulmonary resuscitation immediately.

Situation 3:

Breathing stops. Electric shock often causes breathing to stop.

Action:

Start artificial respiration immediately and monitor the pulse to ensure that blood is circulating. If a flow of oxygen to the lungs can be maintained by artificial respiration until the paralysis wears off, normal breathing will usually begin again.

Situation 4:

Electrical burns. Current passing through the body generates heat and may cause blisters on the skin. If the current is strong enough, it may destroy body tissue and result in severe electrical burns. The outward appearance of electrical burns may not seem serious, but they are often very deep and are slow to heal.

Action:

Standard emergency procedure for burns. Prompt medical attention is required to prevent infection. Examine the victim for an exit burn as well as an entry burn.

Involuntary Muscular Reaction

Involuntary muscular reaction is an effect of electric shock that has been experienced by everyone who has made accidental contact with an electric circuit.

Even household currents may cause the victim to react so he or she is unable to let go and clear himself or herself of the contact.

If the current is strong enough, this involuntary muscular reaction can be sufficiently violent to cause serious damage to muscles and bones. In addition to freezing the victim to an energized conductor, involuntary muscular reaction may cause a victim to jump or fall which could result in a more serious injury.

Reference: Electrical Safety Handbook for Emergency Personnel – Energie NB Power


About Author //

author-pic

Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears. Professional in AutoCAD programming and web-design. Present on



5 Comments


  1. A>Yougaraj
    Aug 20, 2014

    Good, useful articles


  2. Mr.Shankar Khangal
    Jul 17, 2014

    5 Very good site.


  3. Mr.Shankar Khangal
    Jul 17, 2014

    Graduate Electrical Engineer with 44 years experience. Very good site.


  4. C B DESHMUKH
    Jun 06, 2014

    Dear sir,

    very nice presentation made by you we really appreciate for your work well done keep it up.


  5. José Jamal
    Jun 02, 2014

    É um artigo muito interessante, aprendi novas coisas sobre o perigo da electricidade. A informação está bem estruturada e exposta de uma forma clara. Obrigado por partilhar o que tem de mais precioso.

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