W
wade88
Hi chaps,
i was asked to give a presentation to the company work force regarding electrical safety and the basic do's and dont's regarding the unfortunate event of an electrocution occuring or an injury arising from electricity. Ignore by all means as im sure its bread and butter to all of you but thought it wouldnt hurt to post a few bits from my presentation up as some of us may need a little refreshing once in a while. Feel free to correct any of it if you believe the info to be incorrect or just plain crap
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If the current passes through the chest or head there is an increased chance of death. From a mains circuit the damage is more likely to be internal, leading to cardiac arrest.
The comparison between the dangers of alternating current and direct current has been a subject of debate since the 1880's. DC tends to cause continuous muscular contractions that make the victim hold on to a live conductor, thereby increasing the risk of deep tissue burns. On the other hand, mains-frequency AC tends to interfere more with the heart's electrical pacemaker, leading to an increased risk of fibrillation. AC at higher frequencies holds a different mixture of hazards, such as RF burns and the possibility of tissue damage with no immediate sensation of pain. Generally, higher frequency AC current tends to run along the skin rather than penetrating and touching vital organs such as the heart. While there will be severe burn damage at higher voltages, it is normally not fatal.
It is believed that human lethality is most common with AC current at 100-250 volts, as lower voltages can fail to overcome body resistance while with higher voltages the victim's muscular contractions are often severe enough to cause them to recoil (although there will be considerable burn damage). However, death has occurred from supplies as low as 32 volts – bear in mind some hand held power tools, have batteries around 36 volts!
Electrical discharge from lightning tends to travel over the surface of the body causing burns and may cause respiratory arrest.
Point of Entry
The danger from an electrical shock depends on the type of current, how high the voltage is, how the current traveled through the body, the person's overall health and how quickly the person is treated.
Call 999 or your local emergency number immediately if any of these signs or symptoms occur:
i was asked to give a presentation to the company work force regarding electrical safety and the basic do's and dont's regarding the unfortunate event of an electrocution occuring or an injury arising from electricity. Ignore by all means as im sure its bread and butter to all of you but thought it wouldnt hurt to post a few bits from my presentation up as some of us may need a little refreshing once in a while. Feel free to correct any of it if you believe the info to be incorrect or just plain crap
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
If the current passes through the chest or head there is an increased chance of death. From a mains circuit the damage is more likely to be internal, leading to cardiac arrest.
The comparison between the dangers of alternating current and direct current has been a subject of debate since the 1880's. DC tends to cause continuous muscular contractions that make the victim hold on to a live conductor, thereby increasing the risk of deep tissue burns. On the other hand, mains-frequency AC tends to interfere more with the heart's electrical pacemaker, leading to an increased risk of fibrillation. AC at higher frequencies holds a different mixture of hazards, such as RF burns and the possibility of tissue damage with no immediate sensation of pain. Generally, higher frequency AC current tends to run along the skin rather than penetrating and touching vital organs such as the heart. While there will be severe burn damage at higher voltages, it is normally not fatal.
It is believed that human lethality is most common with AC current at 100-250 volts, as lower voltages can fail to overcome body resistance while with higher voltages the victim's muscular contractions are often severe enough to cause them to recoil (although there will be considerable burn damage). However, death has occurred from supplies as low as 32 volts – bear in mind some hand held power tools, have batteries around 36 volts!
Electrical discharge from lightning tends to travel over the surface of the body causing burns and may cause respiratory arrest.
Point of Entry
- Macroshock Current flowing across intact skin and through the body. Current traveling from arm to arm or between an arm and a foot is likely to traverse the heart and so is much more dangerous than current traveling between a leg and the ground.
- Microshock Direct current path to the heart tissue
The danger from an electrical shock depends on the type of current, how high the voltage is, how the current traveled through the body, the person's overall health and how quickly the person is treated.
Call 999 or your local emergency number immediately if any of these signs or symptoms occur:
- Cardiac arrest
- Heart rhythm problems (arrhythmias)
- Respiratory failure
- Muscle pain and contractions
- Burns
- Seizures
- Numbness and tinglingWhile waiting for medical help, follow these steps:
- The person may still be in contact with the electrical source. Touching the person may pass the current through you.
- Turn off the source of electricity, if possible. If not, move the source away from you and the person, using a non-conducting object made of cardboard, plastic or wood.
- Check for signs of circulation (breathing, coughing or movement). If absent, begin cardiopulmonary resuscitation (CPR) immediately.
- Lay the person down and, if possible, position the head slightly lower than the trunk, with the legs elevated.
| Electric Current (1 second contact) | Physiological Effect | Voltage required to produce the current with assumed body resistance:
| |||
| 1 mA | Threshold of feeling, tingling sensation. | 100 V | 1 V | ||
| 5 mA | Accepted as maximum harmless current | 500 V | 5 V | ||
| 10-20 mA | Beginning of sustained muscular contraction ("Can't let go" current.) | 1000 V | 10 V | ||
| 100-300 mA | Ventricular fibrillation, fatal if continued. Respiratory function continues. | 10000 V | 100 V | ||
| 6 A | Sustained ventricular contraction followed by normal heart rythmn. (defibrillation). Temporary respiratory paralysis and possibly burns. | 600000 V | 6000 V |
