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International Conference on Systems, Signal Processing and Electronics Engineering (ICSSEE'2012) December 26-27, 2012 Dubai (UAE) The Effect of Electric Current on the Human Body A. Ouazani, A. Khellassi, I. Habi Tetanizationmuscle: From 7to 8 mA muscles contract. When the intensity reached 10-15mA, clenching of the hand (for a contact hand - hand orhandfeet) on the seized items is such that it is possible to let go: the tetanisation which may extend to the arms and legs. For currents above 25 mA, the trajectory of current in the body may include the respiratory muscles and result in death from asphyxiation. The blocking of the chest can harm the heart and therefore result in electrocution (fatal accident). -Fibrillation of the heart: Fibrillation heart is uncoordinated contraction of muscle (cardiac arrhythmia cycle and loss of synchronism). During fibrillation, the heart's electrical activity is disordered, which prevents effective contraction of the heart. Abstract—Two parts are considered in this study: -In the first one the physiological effects are analyzed: the first sensations due to electric current (the currents are not dangerous in this case), the tetanisation which can have serious consequences especially if the time of current flow is important, cardiac fibrillation which is very dangerous and often results in electrocution and burns. -The second part comprises a non-exhaustive study of the various factors involved in the physiological effects of electric current such as the current, the electrical impedance of the human body, the time of passage of current, the trajectory of current through the human body, the frequency of the current. Keywords— accidents, burns, electric current, electric energy, electric shock, fibrillation, frequency, voltage. I. INTRODUCTION When cardiac contractions are anarchic, the heart can no longer fulfil its role of pump and the person becomes unconscious and not breathing. If this condition is prolonged, irreversible damage appear followed by the death of the victim. -Electrical burns: burns are the most common consequence of accidents due to the electric current. The seriousness of electrical burns is related to all the physical parameters of the accident: current, voltage and time of current flow. Burns due to high voltages are of particular gravity, because in addition to local burns, they appeared deep burns along the current flow in the muscle masses. The arc burns are due to the exposed intense heat and concerns especially parts (hands, face, eyes), but can reach a significant portion of the skin surface and be aggravated by ignition of clothing. Electrothermal burns are due to the passage of electric current and related to the heat and their importance is directly related to the law W = ITU. In the mixed burns, electric arc and the passage of electric current together result in superficial and deep burns. E LECTRICAL energy is today the form of energy most commonly used. It is easy to transport and transform into other forms of energy. In any electrical installation the risk of electrocution (nonfatal accident), electrocution (leading to death) and fire are real. When a person is in contact with two electrodes, it passes through the body an electrical current. The intensity of this current depends on several factors. The danger depends on both the current, time of current flow through the body, the trajectory followed by this current and many other factors which are discussed partially. The different physiological responses encountered when an electric current passes through the human body are numerous and require analysis not only electricians but also by medical specialists (cardiologists, neurologists, occupational physicians ...). II. PHYSIOLOGICAL EFFECTS Perception-current: the current flow of very low intensity is perceptible by a tongue by giving a tangy sensation. Beyond and slightly higher intensities it becomes perceptible to the skin and causes a tingling sensation, then pain. III. FACTORS INVOLVED IN THE PHYSIOLOGICAL EFFECTS OF ELECTRIC CURRENT A. Ouazani, is with the University of Boumerdes Algeria email:[email protected] yahoo.fr ). A. Khellassi, is with the University of Boumerdes Algeria. I. Habi , is with the University of Boumerdes Algeria (email:[email protected] ). A. Current The electrical currents based on their values provoke different physiological actions on the human body. Some 207 International Conference on Systems, Signal Processing and Electronics Engineering (ICSSEE'2012) December 26-27, 2012 Dubai (UAE) C. Body impedance: The impedance offered by the human body to the current flow is not linear. Its value varies in very large proportions and the current through the human body is obviously a function of the impedance. For the same person, the impedance varies with several factors (contact points, the skin condition, the duration of contact, the contact voltage ...). values are interesting to know, what are the thresholds? -Perception thresholds: To 0.45 mA current is percept at the tongue. Beyond and from 0.3 to 3mA the flow of alternating current (50Hz) becomes noticeable at the skin and causes a tingling sensation and pain. Experiments on 169 people showed that the sensation occurs on average for a current of 1.086 mA from Dalziel . For IEC (International electrotechnical commission), the current value perception is 0.5 mA [3,4]. Note that these are average values and depend on several factors. Hence from Dalziel the value of current perception ranges from 0.3 to 99.7 mA . D. Time of current flow: The danger is even greater than the time of passage of current through the human body is big. So the danger is the same for a current of 30mAfor 5 seconds and 300 mA for 0.5 seconds. Indeed during time of current flow, the body impedance decreases and the current through the body increases. Several authors have developed empirical formulas for the current fibrillation versus time of passage through the human body (8.9). Thus according to Dalziel and C.E.I.: Non-threshold drop For currents above the current perception, sensation becomes unpleasant and reached all the hand (touch hand or hand to foot) and can lead to muscle contraction. The threshold of release is not defined by the IEC as the maximum current that can be tolerated by a person. The threshold for non-release depends on several factors. Among these factors include time since the electrical impedance of the human body decreases, implying a contact voltage for a defined increase in the intensity of the current through the human body and lead to death within a few minutes. For example the current value of non-release is set at 10 mA by the IEC  and at 16 mA by Folliot and Dollin [6,7]. -Threshold of ventricular fibrillation: The threshold for cardiac fibrillation depends mainly on the value of the current, time of current flow in the body and the current trip. For a time of passage of current greater than the cardiac cycle(approximately one second), most authors consider that the fibrillation is between 25 mA and 100 mA [3, 4,5]. Towards 25-30 mA, if the circuit cut occurs quickly, the danger of electric shock is unlikely. This explains the choice of this threshold by lawmakers and manufacturers of protective relays acting quickly on the switchgear. Ih= 165 √t and Ih= 10 + 10 t The values for the currents fibrillation are very different, which can be explained by the different experiences of different models in different conditions. E. Time of current flow: The current trajectrory has a great influence on the danger, the electric current circulates through the highest conductance of the human body. These are the trajectories that can harm the heart that induce ventricular fibrillation. Thus according to the IEC the danger to the trajectory from hand to foot is 3.8 times larger than that from hand to hand. F. frequency: The vast majority of common household and industrial distributed at a frequency of 50-60Hz which are the most dangerous frenquencies. For frequencies above 50Hz, the current becomes less dangerous. At 1000Hz the values of current perception, the not release and fibrillation are 2.1 times, 6.68 times and 14 times higher than for a frequency of 50Hz. B. Voltage: The value of the voltage does not represent the danger criterion, the criterion being the current through depends on the contact the body and the current voltage and the value of the electrical impedance of the human body. Thus the means of protection do not refer to the current that is not easily measurable, but the value of touch voltage. The IEC believes that voltages lower than 50V are not dangerous [3,8]. G.Other influences: They are very numerous. Among them are: -age, -Health, -the physical, -the size, -the psychological state, 208 International Conference on Systems, Signal Processing and Electronics Engineering (ICSSEE'2012) December 26-27, 2012 Dubai (UAE)   -room temperature -the ambient atmosphere, the moisture-, -Elevation .......    Table I : Summary curre nt (mA) 0,045 0.5 to 1 6-8 10 15,5 20 30 50 70 to 100 >500 Effects of electric current Sensory level language Perception threshold depending on the state of the skin, light muscle contractions Perception skin shock to the touch Electrical shock, muscle contraction, Threshold defined by the non-release C.E.I. Impossibility of self-liberation of the current Electric shock, tetanization of the thorax, possibility On ventilatory asphyxiation if t is greater than 3 minutes if the current path of interest to the diaphragm (contact by hand) Electric shock, tetanization of the thorax, possibility of ventricular fibrillation if t is greater than one minute Possibility of ventricular fibrillation with a probability greater than 50% and if t is greater than 1.5 of the cardiac cycle Ventricular fibrillation with a probability greater than 50% if t is less than 0.75 of the cardiac cycle; burns Nerve centers destroyed; internal chemical composition, burns veryimportant; almost immediate death IV. CONCLUSION: The statistics of accidents show that the percentage of accidents due to electric current is very low, where as those of deadly accident is much higher. The widespread use of electricity leads to many accidents that can be very serious and a sizeable percentage results in death. The study of the effects of electric current on the human body and that of the electrical impedance of the human organism are essential. A non-exhaustive part has been studied in the present work. REFERENCES     A. Ouazani, Théorie et pratique pour l’amélioration de la sécurité dans les installations électriques.Thèse de doctorat, Moscou 1990. C.F. Dalziel, Electric shock hazard. IEEE Spectrum, 1972.vol.6 N2. Effets du courant passant par le corps humain ». Commission électrotechnique internationale, rapports de la C.E.I, publication 479.1, 1984. C. Remond, Les effets du courant électrique traversant le corps humain JEEE N538 ,1986. 209 Ray Frisch, All about electric shock. Radio electronic, 1985, vol.35 N8. P. K. Dolin, La sécurité dans les installations électriques. Moscou, Energoatomizdat, 1984. D. Folliot, La connaissance des risques : physiopathologie des électrisations, JEEE, N462 ,1980. Effets du courant passant par le corps humain . C.E.I, rapports de la C.E.I, publication 479, 1974.. C.F. Dalziel, Lethal electric current. IEEE Spectrum 1968, vol.6 N2.