In this technical note, we will study the principal effects of the electric current on the human body. One will see the conditions which are dangerous i.e how electrocution occurs and the precautions which one can take to protect oneself. One will also see the old theories on electrocution.
We immediately announce to the reader that the physiological process of electrocution is not entirely known and that certain aspects are still the subject of studies and discussions. Moreover, one will see it, the effect of a given current varies in some limiting from one person to another. Much more, the danger of death grows with the current one up to a certain value for then dropping.
Physiological effects of the current
The physiological effects of electricity depend on the current which circulates in the human body and not of the tension. Obviously, the current is function of the tension applied and the resistance of the circuit, including that of the human body. The effects depend on the path followed by this current in the human body as well as the frequency. It goes without saying the current which circulates between two fingers of the same hand will have less effects than the current which passes through the rib cage.
The dangers which we will describe correspond to those of a current who passes between the two hands or, between a hand and the feet. In the same way, in general, we will refer to currents of industrial frequency (60 Hertz) to a few thousands of Hertz.
There are two theories which are retained at present to explain electrocution. The bulbar theory was proposed by Arsonval in 1887. The effect is the respiratory stop and asphyxiates. According to this theory, one electrocuted must be treated by the artificial respiration, like one embedded.
The second theory is that of fibrillary tremor. According to this theory, death would come from the effect paralysing of the current on the core. The core enters then in disordered oscillations or tremors and death is fast.
These two theories are also valid and one or the other can occur in practise. According to the second theory, the artificial respiration is useless; however, because of the doubt which remains in a given case, the artificial respiration is recommended.
The physiological effects of the various intensities of current at industrial frequencies are given in Table 1. This table requires several comments. The values given are not absolute. They can vary in more or less than one factor two and even more than one individual with the other.
For example, the threshold of feeling can be 0.5 my for certain people and 2 my for others. In the same way, one gives 70 my for the threshold of fibrillation (fibrillary tremor). However, as the following value in the table shows it, it will be noted that 0,5% of the population will not undergo this effect even with a current almost four times more raised, that is to say 250 my.
Effects of the current on the human body at the frequency of the network
More than 5 has
Threshold of feeling
Feeling without pain
Threshold of the muscular loss of control
Respiratory threshold of paralysis
Cardiac threshold of fibrillation
Cardiac fibrillation almost some in 99,5% of the cases
Cardiac paralysis, cardiac arrest, can be reversible
Burns of fabrics
It is necessary to announce that the current necessary for a given effect is roughly proportional to the weight of the individual. Thus, one needs a higher current to electrocute an adult compared to a child. In the same way, in general, the men can resist a current higher than the women; that comes from the mass of the people and not of the sex. This relation of quasi-proportionality between the necessary current to produce a given effect and the mass also applies to the animals.
For example, a cow weighs approximately five times more than one human being and it can carry a current five times higher. One often believes, wrongly, who the animals are more sensitive than the human ones to the electric current; it of it is nothing. We will reconsider this point further.
The values given in Table L are valid for currents of which the duration is five seconds or more. The danger grows a little with the period of validity of the tension beyond five seconds. In on this side five seconds, the danger decrease with the period of validity of the tension. For short times (5s), the minimum current to produce fibrillation is given by:
where I is in my and T in seconds. The value of 116 applies to the case of light people and the other value to heavy people. It will be noted that for T = 5s, these equations give a current from 52 to 83 my. For a time of a cycle with 60 Hz, the current could be about an amp.
According to Table 1, a current of 20 my, although painful, can seem inoffensive. It is not always thus. Indeed, because of the muscular loss of control, the person cannot demolish herself of her influence. For example, if a hand is closed on a pipe, one will not be able to open it. One is thus "fixed" or "cold". The contact could not be broken.
Possibly, the stress associated with this contact will be able to paralyse the victim if nothing is done to release it. This current of muscular paralysis is the term quite descriptive English of "let-go current".
Even a current of a few milliamperes can constitute a danger under certain conditions. Following a low current, there are an unpleasant feeling and a movement of instinctive retreat which follows. This movement of retreat can constitute a serious danger under certain conditions like, for example, if the person is in a scale, a scaffolding or near machines moving. Thus very current of more than 1 my must be proscribed.
The current of about 100 to 300 my must be regarded as the most dangerous level. It is that which produces the cardiac fibrillation of which the effects are almost always irreversible, even when the current is removed after a few seconds.
Cardiac fibrillation is a disordered oscillation of the core. Higher currents, such that a few amps constitute a danger less than the preceding level although the danger is considerable. However, once the removed current, the victim recovers very often, but not always. The high currents often produce burns which can be surface at the contact points or even deep. Because of the powers concerned, there is heating of fabrics. This heating depends on the intensity of the current and the period of validity of this one.
The surface burns, although painful, are often without long-term consequences. They can be treated like other types of burns. However, it often happens that the burns are internes and of fabrics or the internal nerves can be damaged.
These burns will be able to require the cutback of the end of a member. A little later, one will be able to note that the member was damaged than envisaged more initially; it happens that one must carry out some successive amputations because of the internal burns. Moreover, in certain circumstances, of the internal vital bodies can also be damaged; it can then result death from it after a few days whereas the victim seemed well to have recovered initially. For these reasons, when the possibility is suspected that high currents circulated in the victim for a certain time, it is necessary to keep it under observation.
We remind the reader that the values of current given higher are in relation to currents which circulate in the body while passing from one member to another.
Other conditions can be much more dangerous. For example, a current of about 0,02 my which passes directly in the core can produce ventricular fibrillation. It is claimed that there are thus some cases of electrocution in the operating theatres. Thus, of the very weak currents even can be very dangerous if they circulate in particularly vulnerable areas. It goes without saying a current, for example, between the two upper limbs circulates in all the area of the trunk. This current is thus distributed on a great section; a small portion only of this current circulates in vulnerable areas.
It is interesting to note that the current necessary to produce dangerous effects for the human being is very small compared to the usual currents in a residence. A circuit is protected by a fuse from 15 A. a lamp from 100 W consumes a current of 0,8 A. the current required by a bulb of Christmas tree gives already a very unpleasant shock.
The values of currents given higher are in relation to currents of industrial frequencies. In D.C. current, the dangers of electrocution are much less. For a given physiological effect, one needs a D.C. current approximately four times higher than a AC current. Moreover, the phenomenon of loss of control of the muscles which solidifies the person on a conductor does not exist or, at least, is much less. While being based on this fact and some others, at the end of last century, Edison, in a battle with Westinghouse, had tried to make defend the use of the AC current. Edison claimed that the AC current was useful to anything else only electrocution. He even strongly insisted so that the first legal electrocutions are done with machines with AC current.
The physiological effects of the current decrease quickly when the frequency is high. Already, to 10.000 Hz, the necessary current to produce a given effect is multiplied by a factor from five to ten compared to the current with 60 Hz. It is often believed, wrongly, that this effect comes from the tendency of the current at the frequencies raised to circulate on the surface of conducting materials. This effect, for the human body is negligible except at the extremely high frequencies. The danger decrease because the nerves do not answer any more the frequencies raised because of the propagation time finished in the nerves. The effect of heating persists always however. This heating can cause death if it is appreciable. In the circuses, one often sees a person subjected to high voltages. One can note the sparks at the end of the fingers and it can light a fluorescent tube by holding it in its hands. That does not have anything exceptional. One uses simply a generator with high voltage and high frequency. Thus, the person easily carries currents of several tens of milliamperes without problem.
Another case to be considered is that of the intense currents for very short durations as the discharge of a capacitor. In this case, the danger is variable and depends on the moment when the discharge in the cardiac cycle occurs. Here, the danger is depend on the energy accumulated in the capacitor. It is generally considered that an energy of approximately 15 joules constitutes the limit of danger and that 50 joules constitutes a serious danger. This energy is calculated a capacitor easily in the case of by:
É = ½ CV² joule......watt * sec
where C is the capacity of the capacitor in farad and V, the tension in volts. It is seen, a capacitor of 100 µF (microfarad) charged with 1.000 V [50 joules] constitutes a serious danger. On the other hand, a capacitor of 0.001 µf charged with 10.000 V [0.05 joule] does not constitute any danger. It is about the case to which one is subjected when one takes a shock of static electricity by touching a metal object after having walked on a carpet. So that the danger exists, it is necessary that not only the stored energy is sufficient, but also that the tension is sufficiently high so that the current of discharge is dangerous.
A similar case is given by an inductance coil L (as a Henry) which carries a current I (in amp). When this current is stopped, it occurs an overpressure which can be dangerous. The stored energy is given by:
É = ½ LI² joule......watt * sec
In this case, energy is often much higher than that stored in a capacitor. However, this case is not very likely to occur in practise although it is not impossible.
Resistance of the body
It was seen, the physiological effect of electricity on the human body depends on the current. The current depends at the same time on the tension and the resistance of the electrical circuit. This electrical resistance includes that of the source, of the electrolyte which the body constitutes and of resistances of contact to the input and the output of the current in the body. Except for some exceptional cases, the resistance of the source can be neglected. The resistance of the body between two members is about 200 ohms. The greatest part of resistance is that of the contacts. This resistance is very variable according to the nature and of the surface of contact, the pressure, the moisture of the contact, the roughness of the skin. It changes even with the current which circulates and decrease with him. The skin itself constitutes an appreciable part of this resistance of contact. Thus, a wound will be able to affect it. With fairly high tension (a few hundreds of volts and more), the tension is sufficient to bore the skin. Thus, the film which the skin constitutes is destroyed and resistance falls in a Draconian way. That explains why tensions of 300 V and more are much more dangerous than 120 V.
This resistance can vary from 150 Ohm ⁄ cm² for a hand wet and soft on a metal part and up to 100.000 Ohm ⁄ cm² for a callous and dry hand of a workman. If the current circulates in the feet, it is necessary to also include the resistance of the shoes which is, it, very variable according to moisture, of the nature of the sole and the use of nails or wire to fix the sole. The measurements made by various researchers show that the total resistance of the body is about 2.000 Ohm or more under ordinary conditions of contacts. It can go down to 500 Ohm or even a little less in the case of good contacts on large surfaces and be as high as 200.000 Ohm in the case of specific contacts without pressure. A simple fortuitous contact with the hand on a conductor gives a resistance generally higher than 5.000 Ohm.
Thus, to 120 V, a fortuitous contact on a conductor gives a current of 120 ⁄ 5000 = 0.024 has or less. This current, although unpleasant, generally does not constitute any danger. Under other conditions, the such hand closed on a wet pipe and the feet on a very wet ground, the current could be with 120 ⁄ 1000 = 0.12 A. This condition must be regarded as very dangerous and almost always mortal especially if the victim remains fixed on the conductor. It is seen, a shock with 120 V is unpleasant but seldom mortal under the current conditions. On the other hand with a good contact on a solid object like a similar pipe, drilling machine and other cases, it is often mortal. In extreme conditions like the two hands on a wet pipe and the two feet in water, a tension of 20 V must be regarded as dangerous.
On a three-phase system with 600 V, the tension between a wire living and the ground are of 600 ⁄ V² 3. A fortuitous contact of the end of a finger mortal although not is normally not recommended. On the other hand, a contact moindrement well the fact must be regarded as dangerous. A contact with a pair of grips will be very often mortal.
By what precedes, it is seen, the tensions of a few hundreds of volts to approximately 1.000 V are most dangerous. To a few thousands of volts the current is too high to produce fibrillation.
For example 5.000 V, one ad interim = 5.000 ⁄ 1.000 = 5 A. In this case, if the contact is not prolonged, much victims survive, although there can be serious burns. It goes without saying, that with tensions more raised even, the burns, by themselves, are often sufficient to result in death.
In general, with high voltage, the resistance of contact is low since the skin is bored. There will be burns located at the contact points in addition to other burns. Obviously, a contact with 5.000 V, 5 has cannot be maintained a long time. The power is thus of 5.000 X 5 = 25.000 Watts. Such a power, if it were uniformly distributed on all the human body would raise the temperature of this one of approximately 0.2°C a second. It is known that a rise in temperature of the body of a few degrees results in death. There is worse however. This rise in temperature is not uniform and certain parts of the body will be heated much more quickly than what is given higher.
Certain sources with high voltage can not constitute any danger or a weak danger. It is the case if the source has an impedance internes very high. In this case, the current, even in the event of short-circuit, is limited to a low value, in on this side dangerous threshold. It is the case of the transformers for lighting with neon which, although the tension is several thousands of volts (to 15.000 V), the current of short-circuit is limited to 30 or 60 my. At once that the transformer outputs a certain current, the tension falls quickly. It is also the case of the circuit high voltage on the television sets, the system of ignition in the motor vehicles, the filters electronic and some different systems. It is however never the case in the lighting systems, of usual device and socket-outlets.
Electrification of the people
So that there is electric shock, it is necessary that the current enters the body in a place and kind elsewhere. We exclude the electrostatic shock here where there is a transfer of load of an object towards the human body or vice versa. Only one contact on a conductor cannot produce electrocution. If a person touches with a conductor with 10.000 V and that it is isolated from any other conductor, there will be no current which will circulate although the body is thus with this tension. The person will be in the position of the bird which is posed on a conductor with high voltage. The bird will not be made electrocute that if it touches simultaneously with two conductors or, still, with a conductor and an object put at the ground.
Figure 1 shows a typical system of feeding in a residence. This system is to 120 ⁄ 240 V and is also used even in commercial and industrial medium for the installations of low powers like lighting, the socket-outlets and various small apparatuses and devices electric.
Contact on a circuit with 120 ⁄ 240 V
A person who makes contact between conductors L1 and N or L2 and N is subjected to a tension of 120 V. If it makes contact between L1 and L2, it is subjected to 240 V.
These three cases occur occasionally but they are rather rare. On the figure, one shows also the conductor of continuity of the masses by the letter Mr. C’ is the naked conductor or with green insulator which is put at the ground and connected to the metal cases of the electric devices.
A fortuitous contact between L1 and m or L2 and m will produce the same effect as the contact between L1 and N or L2 and N. This type of fortuitous contact is more frequent than the preceding cases although it very often does not arrive. Between N and m, the tension is null and one can touch these conductors without danger, although that is not recommended.
The most frequent case is that where a person touches one or the other of the conductors L1 or L2 and makes simultaneously contact with the ground or an object put at the ground a such case, a structure or metal decline. Under this condition, the power is on through the person and turns over to the source by the objects put at the ground or by the ground itself. The resistance of the ground is very variable and depends on many conditions such as the nature and the moisture of the ground, the surface of contact and many other factors. This resistance can go from almost null to a few hundred ohms. In the majority of the cases, this resistance is low compared to that of the body and thus, it will not limit the current.
The Figure shows a three-phase system, for example, at 600 V. the neutral conductor is put at the ground. Each conductor has, B and C is with a tension of 600 V² 3 = 347 volts compared to the ground. A person touching simultaneously has and B, B and C or C and has will be subjected to 600 V. This case is rare.
The most frequent case is of affecting one of the conductors has, B or C and, simultaneously, touch the conductor N or the ground Mr. In this case, the person will be subjected to 347 V. One will have noticed that, in the networks single-phase currents to 120 ⁄ 240 V, the electric shocks are almost always to 120 V. In the three-phase networks, the electric shocks most current are with the nominal voltage divided by the square root of three.
Another case of danger which arises in practise is that where a metal mass becomes electrified because it makes contact with an alive electric conductor. Thus this metal mass becomes with the tension of the circuit. The famous Figure this case. On the left, we show the source V and, on the right, an unspecified load R in its case E.
Electrical circuit with electrified case
An alive conductor L feeds the load with 120 V and conductor N is the conductor of return. In dotted line, we show the conductor m of continuity of the masses which connects the case of the load to the ground.
Let us suppose that a fault occurs and that the alive conductor L comes in contact with the case. Under this condition, a high current will circulate in the conductor L to return to the source by the conductor Mr. This current high will quickly make open the fuses by supposing that the conductor of continuity of the masses has a low impedance. The system is thus protected.
Let us suppose now that the conductor of continuity of the masses m is not used or is open. Under this condition, following the fault at the point K, the case becomes electrified to 120 V.Toute anybody who will touch this case and the ground or an object which is connected there will take an electric shock which could be mortal if the contacts of the person on the case and the ground are good.
Let us note that if the case is put at the ground because it touches the ground or a floor of concrete, the continuous danger to exist. Indeed, the resistance of the return circuit which is done in the ground will be about a few tens to a few hundreds of ohms. To 120 V, the current will be, to the maximum, of a few amps and protections will not open. It is necessary that the path of return of the conductor of continuity of the masses has a low impedance to make open protections in the event of problems.
This conductor of continuity of the masses corresponds to the third leg or limits round on a socket-outlet or a card. This conductor is useless in normal functioning and does not carry any current. It is however of a great utility in the case of certain faults as one has just seen it.
Means of protection
There exist many means of preventing electrocutions. We will study some of them. With the preceding section, we already discussed the protection which constitutes an earthing and a conductor of continuity of the masses and we will not reconsider this point. There are effective solutions and obvious that we will not discuss here such of the fences, limitation of access, distance of the conductors, insulation of those and many other average mechanics or others which prevent the accidental contact. That makes the object of many codes and procedures. We occupy ourselves only principles here.
An effective way to protect the people is to make apparatuses with a double insulation. The apparatus (for example a drilling machine) is built in a normal way, with the conductors which are isolated from the case. Moreover, an additional insulation is added if the first level of insulation would become defective. That could be made with a case entirely built out of plastic. It would still be necessary that the chuck is electrically isolated from the other metal parts of the drilling machine. It is an interesting solution but which supposes a regular checking. Indeed, one of the two levels of insulation can become defective and there does not remain more but one then about it. This first defect will pass unperceived except if the apparatus is checked regularly.
To supply certain small apparatuses in dangerous places, one uses sometimes a transformer of insulation
Transformer of insulation
It is often used for the socket of shaver of a bathroom. It will be noted that the secondary circuit or of the razor is connected any more to the ground in some way only it is. If there is fault and that the case of the razor has suddenly touched with an alive conductor, that will not cause any problem because the person who uses the razor will not complete any and it will circulate no current.
It is often believed that the systems put at the ground are sedentary than the floating systems. It is true in much case, but not always like illustrated the preceding example.
Differential circuit breaker
The differential circuit breaker or of detector of leakage current to the ground (GFI, Ground Fault Interruptor), detects the current which goes to the load and which in cost. If these currents are not equal, it is that there is a leakage current with the ground and the system opens a switch after a very short time. In general, a difference of 5 my is sufficient to open the circuit but there exist other sensitivities. The time of opening is about milliseconds. It goes without saying that gets a very good protection against electrocution if there is a leakage current through a person towards the ground or the conductor of continuity of the masses. The circuit does not protect however from a contact between the conductor living and the neutral.
The Figure shows a schematic diagram of the operation of this system. The two conductors which feed the load pass through a magnetic core
Detector of escape to the ground
If the sum of the two currents in the conductors is null (the current towards the load is the same one as that which in cost), then the magnetic field is null and no tension is induced in the circuit B. If there is a leakage current towards the ground, there is a magnetic field in the core has and a tension induced in the reel B. This tension activates the relay R and opens the switch S. In practise, the electrical signal out of B is small. One adds a system of amplification to make operate the relay.
Production of a tension of neutral
For several years, one has known rather well the dangers of electricity with regard to electrocution. It goes without saying this knowledge can always be improved. This type of study is not easy since it implies internal human beings and phenomena with those. Certain experiments can be led without problems on the human beings. It is the case, for example, of the electrical resistance of the body or the effect of the low currents. For obvious reasons, it is not easy to make studies in cases which present dangers although that could be made in the case of legal electrocutions or following accidents. Even tests on animals comprise many restrictions and severe protocols.
Finally by protection measure all the parts metal of a house likely to be in contact with human or an animal must be to connect to the ground either with a specific case of connexion, or directly on the ground terminal of a socket
Risk run by the human body, crossed by a AC current (of 15Hz with 1000Hz):
Threshold of feeling - Feeling very weak
Threshold of not released - muscular Contraction
Threshold of paralysis - Paralysis ventilatory
Threshold of cardiac fibrillation irreversible
Effects of the passage of the AC current
Perception of the effects
0 to 1 my
Threshold of feeling according to the state of
Shock with the touch, brutal reactions
Contraction of the muscles of the members - crispations durable
4 minutes and 30 seconds
Beginning tetanization rib cage
Ventilatory paralysis and ventricular fibrillation
Ventilatory paralysis and ventricular fibrillation
To approach an installation with high voltage presents a mortal risk
You run a danger, even when you do not touch an element with high voltage. Indeed, when one is too much close to an element with high voltage, it is formed an electric arc which can put your life in danger. If a line with high voltage to lie on the ground following an incident, you hold with at least 10 metres and inform the services immediately, by calling the emergency number. The security distance differs according to the levels from tension. The more this one is raised, the more the distance increases. You always hold with at least 10 metres of any installation with high voltage. The conductors of a line with high voltage can oscillate laterally in high wind conditions (until a score of metres in certain extreme cases). In hot weather and when a line is under strong load, it dilates and subsides, (losing sometimes up to two metres height). The distance compared to a given point can thus change considerably. It will be advisable to hold of it account at the time of the determination of the security distances.
Access to installations with high voltage
The access to installations with high voltage by people not - authorised is strictly prohibited. Only the people having received an express permission have the right to penetrate there.
Climbing of pylons with high voltage
The climbing of pylons with high voltage by not qualified people presents a mortal danger. It is thus strictly prohibited. This prohibition is clearly indicated on each pylon. On the pylon itself, it can indeed happen that one is too much close to the onducteurs and that one starts a disruptive discharge. Elia does not assume any responsibility as for the consequences for such accidents.
Activities at the risk
In a certain number of activities, it is advisable particularly to pay attention to the possible risks that little has the proximity with installations to high voltage.
Construction, work using cranes, of lifts, ladders
Whoever wants to undertake building work near an air line or to carry out work using tools or of large-sized machines is held to consult a technical secretariat as a preliminary. This rule also applies when one must pass under a line with a transport unusual height.
To fly near our lines presents a danger of death. This is valid for the flights in the helicopter, sailplane, the private plane, ULM and the hang glider, but also for the practise of parachuting, the parapente or ballooning.
Any contact, even any too large proximity with an air line, starts a disruptive discharge which can have consequences mortals. Hold account owing to the fact that the visibility of a line with high voltage can be reduced by the reverberation, the fog or the rain.
Information on the localisation of the lines with high voltage can be obtained from the Ministry.
Fishing canes and other objects of big size
To fish near lines with high voltage can also present a danger. The materials of which fishing canes are made up are generally of good conductors of electricity. These canes are often very long and during a throw, the distances are often difficult to evaluate. Thus fish never near a line with high voltage and avoid passing under an overhead cable with a fishing cane.
It is also advisable to be conscious of the risks at the time of other activities (like the erection of a capital, pole of flags, antennas or other constructions of high size under a line with high voltage). Whoever wishes to set up this type of constructions of high size to less than 100 metres of a line with high voltage is legally held to consult the authorities as a preliminary proper.
This rule also applies to the plantation and the maintenance of trees in the vicinity of an air line. We request from the owners grounds located under a line at high voltage not to carry out plantations on both sides exceeding three metres height in a tape of twenty metres along the axis of the line with high voltage. This will avoid work of pruning when the trees push too much close to the conductors after a few years.
The practise of the kite or the model aircraft making near a line with high voltage can also cause a disruptive discharge. When an object is taken in lines with high voltage, never try from of to release it.
For all work with less than 100 metres of an installation with high voltage, it is obligatory to make contact as a preliminary with one of the technical secretariats. Those have all the necessary informations with the realisation of work under optimum conditions for security.
The height of the buildings located near a line at high voltage is subjected to certain legal limitations. The authorised height depends on the type of connexion, certain environmental factors (wind and temperature) and distance between two pylons. Before the beginning of any project or the delivery of very allowed to build, collaborators to the site go in order to take measurements height. The applicant receives then free an opinion written, on the basis of these measurement.
Work using machines of high size
Whoever wishes to work with cranes, lifts, general purpose excavators or objects of big size (like scales), must obligatorily consult a technical secretariat in order to be able to take the security measures which are essential. This is preliminary also for work of roof or on scaffolding to less than 100 metres of an air line.
Always respect the security distances and observe the following rules :
Take account of the wind and possible movements of the line and machines
You of the presence of a person ensure who will take care that the prescribed security distance is always respected during work
The deliveries of hardware must be also carried out remotely sufficient of a line with high voltage
It is essential that any person present on the building site is informed potential dangers and security measures to be taken.
Whoever wants to carry out excavation work must make sure that no underground cable with high voltage is hidden at the place where work must take place. It is thus obligatory to contact technical secretariats before the beginning of work. Those can provide a plan of situation of our installations taking again all the indications necessary: way, depth, width,
Excavation work near pylons with high voltage can have effects on the stability of the latter. Do not take any risk and consult here still our technical secretariats.
In the same way, during work with agricultural units of high size under lines with high voltage, it is advisable to take care that those do not touch the conductors and the pylons or too much does not approach any.
The interventions of the fire protection organisations in an installation of stations or cabins with high voltage are only authorised with the supervision of qualified personnel. Electrical installations must indeed be put not under tension before any intervention of fire control. In the same way, of the security measures must be taken at the time of operations of extinction to water close to a line with high voltage. At the time of an intervention, the scaling ladders can approach lines with high voltage dangerously. A fire under a line with high voltage can also cause a disruptive discharge or involve a rupture of the cable. An air line lying on the ground can also be under tension. You hold with good distance and do not touch it under any pretext.