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100% way out of the situation when there is no protective ground

October 20, 2016
Specialization: master of interior and exterior decoration (plaster, putty, tile, drywall, wall paneling, laminate, and so on). In addition, plumbing, heating, electrical, conventional cladding and balcony extensions. That is, repairs in an apartment or house were done on a turnkey basis with all the necessary types of work.

Currently, approximately 95% of household appliances are manufactured with the need for grounding. This is especially true for those units that are associated with water:

• dishwashers;
• pumps;
• electric water heaters;
• washing machines, etc.

When such a device works without protective grounding, it can shock, which was more than felt by housewives who have automatic machines.

Grounding in its absence

Note. There are four types of grounding: protective, working, grounding and grounding.

What is protective earth and ground fault

We will not go into terminology, but we will find out in the basis what is needed for everyday life. Let's start with the definition - grounding is the intentional connection of a grounding device from a certain point of electrical equipment or a network.

• of all four types of grounding, we are only interested in two - protective and short circuit to the case;
• the essence of protective grounding is to drain the current to the ground, if a phase current enters the mass, from which the RCD is triggered;
• in new houses, a working ground is provided, that is, there is a special bus on the electrical panel where the third core is connected;
• but in the old houses from the time of the construction of Stalin, Khrushchev and Brezhnev, such a function is not provided;
• everything is explained here quite simply - during their construction, there was simply no need for grounding;

• in old houses there is no way to make a protective ground, so here you can make a short to ground, the diagram of which you see above;
• the essence of such a connection is as follows - zero is shunted with ground and if the phase current enters the case, then a short one occurs, from which a residual current device (RCD) is immediately triggered - it must be installed!

A residual current device for household appliances, if connected to only one of them, should not exceed 16A. Otherwise, there may be a delay with the shutdown.

Themselves with mustaches

In front of you is an electrical panel, which is located on each entrance area. Everything located on that floor is powered from it - there can be two, three, four or even five (depending on the type of building).

On the right side of the photo you see the bus to which the cores are connected - this is zero. But if the shield had a ground, then there would be another bus of the same type, to which you would connect the third ground wire.

Sometimes a short to ground is made right here, on the shield - that is, a wire is pulled from the electric boiler from the ground terminal (or from the casing) and connected to the neutral bus. Personally, I don’t see the point in this - why go so far if everything can be done on the spot.

In the picture above you see the panel of the GORENIE boiler, where on the left there are blocks for connecting wires - phase, zero and earth, which are located from left to right. Also there is a shunt jumper connecting zero to ground.

Agree, this is much more convenient than dragging a separate wire to the shield in the entrance, and connecting it to zero there. It is noteworthy that such a small jumper performs the same function as a long wire, so I advise you to do just that.

Those residents who have old-style electric boilers, where an earth terminal is not provided, can also make the same connection. After all, as you understand, the point is to short to the case, therefore, shunt zero directly with the casing. Do not forget that the boiler should be connected through the RCD.

A short to ground can be arranged through the outlet by shorting the zero and ground terminals, as shown in the photo. In this case, it is better to pass the wire from behind (it is not difficult to pull out the socket from the socket), but here I left it in front for clarity.

To carry out the actions, turn off all electrical appliances in the apartment and find the zero terminal on the outlet with the indicator. If the devices are not turned off, then zero will glow, like the phase, and it will be difficult for you to determine it.

Then, with a piece of wire with a cross section of at least 0.5 mm2, install a jumper between zero and ground - absolutely all devices can be connected here.

In fact, in this way you can save yourself and your family not only from unpleasant sensations, but also, in some cases, save life and health, since everyone's perception of electric shock can be different.

These are far from empty words, and in any RES or PES you can be provided with many fatal cases from electric shock, and at low voltages.

Conclusion

For those who doubt, I propose to conduct such a test at home - take a battery-powered indicator and check the machine during operation - in 90% of cases it will light up! For sensitive people, this is expressed in tingling with an electric current.

The option I proposed removes this problem completely and 100%. If you have any suggestions, notes or questions - join my blog on this page.

And for a more detailed acquaintance, especially for you, I made a video - look!

October 20, 2016

If you want to express gratitude, add a clarification or objection, ask the author something - add a comment or say thanks!

If, when touching the refrigerator, you feel light and unpleasant tingling, it means that current is leaking to its case. And this is a direct threat to your health and even life!

The lower limit of sensitivity of dry skin of the human hand is 30-40V. Permissible norm for health - 36V.

On the body of the refrigerator may be present up to 110V alternating current! This is almost half the mains voltage (220V).

Hence the simple conclusion: if your refrigerator began to “fight”, immediately call the master VseRemont24 to your house.

Note! The problem of current leakage to the refrigerator case may not be hidden in the refrigerator itself, in outlet to which it is connected!

Modern refrigerators are quite powerful appliances that “pull” a lot of electricity. The refrigerator must be connected to grounded euro socket!

If your house does not have three-phase wiring to “ground” (and the probability of this is very high!), It makes sense to do this, as well as reinstall the correct outlet.

If you have a ground in your outlet, check if the contacts are oxidized, this may lead to the fact that grounding does not occur.

Note that most refrigerator manufacturers, when creating their “smart” units, expect that they will be connected to grounded sockets!

A refrigerator, on the body of which current passes, must be used strictly forbidden! Remember that such a refrigerator should never be touched with wet hands, especially while the motor is running. Also, do not touch the refrigerator and the heating battery at the same time.

The situation is especially dangerous when the refrigerator is installed on a metal stand.

After the first time you feel a slight electric shock, turn off the refrigerator and call the VseRemont24 masters! It is especially important to do this if there are children and animals in the house.

The master of VseRemont24 will arrive at the most convenient time for you with a special diagnostic device - a megohmmeter. This device allows you to detect exactly where the insulation of the wiring is broken, because it is precisely wiring problem- the most common reason that the refrigerator whiling away.

Faulty in the refrigerator may be:

• fork,
• electric wire,
• wire connected directly to the motor-compressor,
• thermostat knob.

Any of these details are mastered by VseRemont24 quickly and efficiently will replace to a new, “native” for the brand and model of your refrigerator.

Repair of a refrigerator that is beating with current, as a rule, does not take much time, the malfunction will be eliminated within an hour!

The master will give you the exact price after diagnosing and finding out the reasons for the breakdown. In addition, the repair price always depends on the brand and model of the refrigerator.

Do not doubt that after the repair carried out by a highly qualified VseRemont24 master, you will be safe again, and the refrigerator will be a properly working household appliance.

In today's article, I would like to tell you about such a phenomenon as a short circuit in a computer. Yes, right inside the system unit!

A short circuit (abbreviated as short circuit) occurs, as a rule, due to a violation of the insulation and contact of conductive elements with each other. Also, "short circuit" can be caused by the ingress of a foreign metal object inside the system unit.

It may seem to you that in this way it will not be possible to cause a short circuit in the computer and no foreign objects will be there? I will give one example: my friend made an order (for a client), screwed the motherboard, installed other components. The computer lay on its side for ease of assembly. The acquaintance did not notice how he dropped one of the mounting screws. The metal screw fell unsuccessfully, covering (shorting) the adjacent contacts of one of the motherboard microcircuits.

Then the following happened: after applying voltage (turning on the computer), at the point where the “tracks” touched the screw, a friend saw a spark that flared up, in fact, a short circuit. After that, the board was hardly "pushed" under the guarantee.

Let me give you another example, when a short circuit was caused by water that got into the computer, well, at first it was snow, and then water :) The situation was as follows: I had to urgently carry out the prevention of the old one. Dust has accumulated in it - the sea. Gotta blow it. I open the window (it was winter and a little snow fell), I put the open computer on the windowsill and start blowing dust out of it with a vacuum cleaner.

The bad thing was that while I was doing this, a certain amount of snow swirling in the air managed to get into it, but I took this into account and decided for myself that I would let the computer settle and dry before launching. But, as happens in such cases, His Majesty Chance intervened! :) While I was away from the office, the boss gave the command to my partner to urgently bring the "machine" into working condition and give it to the employee.

From the words of a partner: "I turned on the computer, the fan on the processor swung and the system unit turned off ..." As you know, water is an excellent conductor of electricity. The snow melted and moisture formed, after applying voltage, a short circuit occurred in the computer, which led to its emergency stop.

In the latter case, I had the hope that the next morning (when everything was dry) the computer would turn on. I saw something similar before. And this time we were lucky - the next day everything worked again (no oxidation or destruction of the printed "tracks" on the board occurred under the influence of moisture) and the computer still works. So be aware of the possibility of such a situation!

So, after so many letters, let's move on to the practical part of the article and analyze the cases of a short circuit with a few examples. We had one system at work. At first everything was fine, but after a while it started to reboot spontaneously. It got to the point that - five or six times a day. Testing for potential, as well as nothing anomalous, was revealed.

The power supply was replaced with a known good one - the same thing, the whole complex of diagnostic procedures was carried out, and with the same lack of a positive result. All power cables and the surge protector itself, coming from the power outlet, were replaced.

I must say that the room was quite noisy, so I only then heard, sometimes occurring at an arbitrary moment in the system's operation, a barely audible crack coming from the system unit. The crackling in the computer was heard sometimes quite distinctly, but visually no signs of sparking or short circuit were found.

Since the computer did not seem to be going to "die" here and now, I decided to carry out experiments further. And then, right during the diagnostics, a thing happened that finally convinced me that we were dealing with a short circuit in the computer. Visually, it looked like this: the next time you turned on the fan, it didn’t start and after three or four seconds the computer turned off with a click. Computer turns on and then immediately turns off! It looks like it's short circuit protection. We suspect that the motherboard is shorting to the computer case. And, apparently, from its reverse side.

I played around, it means (with the same result) a little more and decided: since the PC didn’t burn out right away, we’ll repair it! :) I must say right away that the malfunction was successfully fixed, and below I want to tell you in detail what and how I did.

To begin with, let's look under the lid :) Here is our place of work:

Our task at the moment will be to completely remove the motherboard from. A short circuit, apparently, occurs at the place of its contact with the rear wall (under the mounting screws).

First, we need to disconnect all power connectors and data cables. For beginners in this matter, the places marked in the photo above may be the most difficult. This:

• 20 (or 24 pin)
• 4-pin connector for powering the processor via a 12 Volt line

Let's remind ourselves how it's done.

As you can see from the photo above, there is a special latch-latch on the seat itself, on which the connector mount is thrown and fixed behind it. In order to remove the connector without any effort, you need (in the place indicated by the cross) to press it with your finger, the mount will come out from under the protrusion and the entire connector can be easily pulled out.

Next in line is the multi-pin power supply of the motherboard:

With him - a similar situation: with a finger we press the plastic latch, it - comes out from under the ledge - we pull the entire connector towards ourselves in the direction indicated by the arrows.

The remaining elements of special clamps do not have, so you can handle them without difficulty. Here is what I got in the process of dealing with a short circuit of the computer:

As you can see, the board is completely free of all cables, except for signal wires, wires for the "start" and "reset" buttons. It is not necessary to disconnect them, in our case.

What do we need to do now? Actually, find and unscrew all the mounting screws. This is how we do it with a Phillips screwdriver (highly desirable - magnetized):

There can be from six to ten such screws. We unscrew them all and carefully remove the board from the case.

We remove it to the side and pay attention to the mounting bushings, of which we have six here. Screws are screwed into them, fixing the textolite base.

I propose to slow down a bit and reflect on why we are doing all this? Since a short circuit in a computer occurs at the point of contact between the motherboard and the case, it would be logical to assume that it is these attachment points that should be isolated!

A crack in the computer (short circuit) can also occur at the point of contact of the mounting screw with the board itself. Therefore, we will carry out double insulation. And we will carry it out with the help of ordinary insulating washers made of thin thick cardboard.

Cardboard base, half a millimeter thick with a hole in the middle. You can make such washers yourself by knocking them out of thick paper (about 250-300 grams per square meter) using a hollow metal tube. Well, or if you don't feel sorry for the time and nerves - cut it out with scissors by hand :)

So, we put our insulator on the screw:

We pass it through the hole in the board and - Attention!- on its other side, we put another insulator, and screw the mounting sleeve onto the remaining free part of the screw thread.

Thus, we have organized double protection against short circuits (on both sides of the screw).

Now it will not cause a short circuit in the computer, since it physically no longer touches its metal case. This is what our isolation looks like:

Our work on the fight against short circuit is almost finished. Now we just have to install the motherboard back into the case and screw the mounting sleeves into the corresponding holes on the back wall.

Let's, for clarity, remove the second side cover and see what is under it?

Pay attention to how many (at first glance, superfluous) threaded holes are made on the back wall. The fact is that different manufacturers of motherboards can arrange holes for fasteners on their products in different ways. And in this situation, case manufacturers should get out and provide for all possible installation options. That is why, in a good case, the back wall looks like it was discharged with a clip of a machine gun :)

We evenly tighten all the bolts, connect the data cables and power cables:

I can say that this "ward" of ours is still briskly spinning all his fans, and his owner recalls a short circuit in his computer as a moment, although unpleasant, but has long faded against the background of other exciting events :)

A classic of the "genre" can be considered an incident that happened recently at our place of work. It is very indicative for two reasons: firstly, it shows us what a short circuit is, and secondly, what are its consequences if the computer protection does not "see" the short circuit in time and does not react to it.

Came to us at work to repair an old PC. Of these, we make terminal clients. If you are interested, you can read about it. The power supply has failed. As a result, the computer does not turn on. In such cases (for primary diagnosis), I usually use a test good block. I just plug it in and if the computer “starts up”, then it’s immediately clear that the reason is in the power node.

Here I gave it to someone and substituted the first old PSU that came to hand. I wish I hadn't done this, of course, but, on the other hand, then we wouldn't have had some interesting photos :) So, I set it up, so I turned it on .... and heard a loud "clap!" in the area of ​​\u200b\u200bthe old one, which was equipped with a computer. "Short circuit!" flashed through my head. The old power supply did not have time to "react" and let the computer turn on! As a result, a "breakdown" of the board component occurred at the place of the short circuit.

Moreover, what is interesting: after the pop, I saw how the component on the map flared up and started to burn! Yes Yes. It is to burn, with such a cheerful tongue of flame! :) Quickly pulling out the power cable, I proceeded to inspect the fire. Let's explore together!

We clearly see a burnt place on the board. By the specific smell, it could be assumed that one of the capacitors caught fire. Let's take the board out of the case and take a closer look at it:

This is true! As a result of a short circuit, one of the capacitors ignited on the board. We can call him. We are convinced that it is still "pierced" (moreover, in both directions).

Everything is exactly as we expected: it did not go into protection mode and allowed the short circuit to fully manifest itself. As a result, I repeat, we have these "wonderful" photos :)

Note: in approximately the same (only more intelligent) way, using a laboratory power supply, motherboards and other elements are checked for a short circuit in them. Voltage is forcibly applied to the board (previously set on the scale of the laboratory unit) and they look at which of its components starts to heat up excessively or behave abnormally?

We did it from the heart, with a twinkle, as they say! :) The voltage was too high and the element flared up.

This is not the end of our story! It was experimentally established that although the computer motherboard remained intact, its hard drive failed. It is no longer detected in the BIOS (moreover, the system "saw" another delivered HDD). With a deeper diagnosis (by palpation), it was revealed that one of the controller microcircuits is overheating. Moreover, this is the classic temperature at which hard drive microcircuits usually "are ordered to live long."

Here is the element that overheated (the temperature of the wall of a hot cup of tea - you want to pull your finger away).

To be honest, I have never tried to measure such a temperature, but then I myself became curious. Decided to do it! Let's use our infrared non-contact thermometer (pyrometer). Let's place it over the "injured" chip and measure it.

What is protective earth? What is its scope?

Protective earth is an intentional electrical connection to earth or its equivalent to non-current-carrying metal parts of electrical installations that may be energized.

The scope of protective grounding is three-phase networks with voltage up to 1000 V with an isolated neutral and above 1000 V with any neutral mode.

What is a short circuit to the electrical installation case? What is the main cause of a short to ground? Short circuit to the body - an accidental electrical connection of the current-carrying part with metal non-current-carrying parts of the electrical installation.

In what case and how dangerous can a person touch the body of an electrical installation isolated from the ground?

If the electrical installation is isolated from the ground, then in the event of a phase-to-case short circuit, touching the installation will be just as dangerous as touching the phase wire, a person standing on the ground or on another conductive base may be under a touch voltage ** almost equal to the phase voltage of the network - 220 V. In this case, a life-threatening current will pass through the human body

I h = Uetc/Rh=Uf/Rh= 220/1000 = 0.22 A = 220 mA

where Upr - contact voltage, V; Uph - phase voltage, V; R is the resistance of the human body, taken as 1000 ohms in calculations.

What is the principle of operation of protective earthing?

Operating principle protective grounding of electrical equipment is to reduce the contact voltage to safe values Uetc, caused by a short circuit to the body. This is achieved by reducing the potential of grounded equipment f 3 (by reducing the resistance of protective grounding R 3 ),

In what way, when shorted to the case, can the potency be reducedgrounded equipment?

Reducing the protective earth resistance R 3

When a phase is shorted to the body of a grounded installation, what determinestouch voltage?

Then, in the event of a phase short circuit to the body of a grounded electrical installation, the contact voltage Upr under which the person touching the body will be, will be -

Uetc= f 3 - phos

where f 3 - the potential of the body of a grounded electrical installation, V; phos - the potential of the base (platform) in the place where the person stands, V.

Will safety increase with an increase in the resistance of the protectivegrounding?

No, because the principle of protective grounding is achieved by reducing the potential of grounded equipment f 3 (reducing the resistance of protective grounding R 3 ), and also by increasing the potential of the Phos base in the place where the person stands, to a value close to the potential of the grounded equipment.

At what minimum AC voltage should protective earthing be carried out in all cases?

According to the Electrical Installation Rules, protective grounding should be carried out: at a voltage of 380 V and above alternating current in all cases;

What is a grounding device? Which distinguishtypes of grounding devices?

A grounding device is a set of ground electrodes - metal conductors - electrodes 7 that are in direct contact with the ground, interconnected by a strip 6, and ground conductors 3 connecting the grounded parts of the electrical installation 1 with the ground electrode.

Depending on the location of the grounding conductor relative to the grounded electrical equipment, two types of grounding devices are distinguished: remote and loop.

What is a group grounding? What are its benefitsschistva before single?

IN loop grounding device(see Fig. 2) use a group of ground electrodes, consisting of several parallel-connected single ground electrodes (electrodes) 7, which provides the lowest resistance to protective grounding.

With a group ground electrode in the zone of current spreading, an increase and equalization of potentials on the surface of the site is observed. As a result, the contact voltage is reduced and, consequently, the safety of people working on the protected site is increased.

What are the advantages of a loop grounding device? How far apart should the electrodes be placed in it?

In the event of a short circuit to the body of the electrical installation, the flow of current into the ground from all the electrodes of the ground electrode occurs simultaneously (see Fig. 2). On the potential distribution chart on the surface of the protected site, obtained by adding the potential curves from each electrode separately, it can be seen that with a group ground electrode in the current spreading zone, there is an increase and equalization of the potentials on the surface of the site. As a result, the contact voltage is reduced and, consequently, the safety of people working on the protected site is increased.

When placing the electrodes at a distance of no more than 8 - 10 m from each other, the maximum values ​​of the contact voltage in this case will not exceed the permissible levels.

What is allowed to be used in enterprises as naturalgrounding conductors?

As natural grounding you can use: various metal structures of buildings that have a connection to the ground; reinforcement of reinforced concrete structures; lead sheaths of cables laid in the ground, water and other metal pipes, with the exception of pipelines for flammable liquids, flammable or explosive gases, as well as pipelines covered with insulation to protect against corrosion.

What is used as artificial ground electrodes?

For artificial grounding Usually vertical and horizontal electrodes are used. Steel pipes buried in the ground, steel angles, metal rods, steel bars, etc. are used as vertical electrodes. Strip steel or round steel bars are used to connect vertical electrodes.

What value should be the resistance of the protective earthinstallations up to 1000 V? How often should it be monitored?

When current drains from the case to the ground 1 3 (see Fig. 1) through a low protective ground resistance Rz, which in electrical installations with voltages up to 1000 V should not exceed 4 ohms.

On the value of what parameter of protective grounding depends on the effectthe activity of his action? How often should this parameter be monitored?

From the value of protective grounding resistance Rz.

In accordance with the requirements of the Rules for the Installation of Electrical Installations, the control of protective grounding resistance is carried out before grounding is put into operation and periodically, but at least once a year.

How does the contact voltage change with increasing distancebetween a person and a ground conductor?

The tension is rising. Then, in the event of a phase short circuit to the body of a grounded electrical installation, the contact voltage Tsch, under which the person touching the body will be

And SCH = f 3 - phos,

where f 3 - the potential of the body of a grounded electrical installation, V; phos - the potential of the base (platform) in the place where the person stands, V.

What is nullification? INtoWhat electrical networks does it apply to?

Zeroing is a deliberate electrical connection with the zero protective conductor of the housing and other metal non-current-carrying parts of the electrical installation, which may be energized.

Grounding is used in networks with a dead-earthed neutral.

What is called a zero protective conductor? Than zero prowater differs from the zero protective conductor?

Zero protective conductor PE called a conductor connecting zeroed parts, for example, the body of an electrical installation with a dead-earthed network neutral.

Zero protective conductor should be distinguished from neutral wire N, which is also connected to a solidly grounded neutral, but is intended to supply current to electrical equipment.

What is the purpose of the zero protective conductor?

Purpose zero protective conductor - the creation of an electrical circuit with low resistance so that the short-circuit current Ikz is large enough to quickly operate the protection.

In what case does grounding eliminate the danger of electric shock?

Zeroing is used to eliminate the danger of electric shock in case of contact with metal non-current-carrying parts of electrical installations that are energized due to a short to the case.

What is a short circuit to the electrical installation case? What is the mainreason for a short circuit?

Short circuit to the body- accidental electrical connection of the current-carrying part with metal non-current-carrying parts of the electrical installation.

The main reason for a short circuit to the case is damage to the electrical insulation of live parts under voltage.

In the event of a short to the body and the absence of zeroing under whicha person can turn out to be yarn by touching the body?

If the electrical installation is isolated from the ground, then in the event of a phase-to-case short circuit, touching the electrical installation will be just as dangerous as touching the phase wire - a person may be under the contact voltage Upr, which is almost equal to the phase voltage of the network - 220 V.

What is the principle of zeroing? Which device has the maximumcurrent protection provides more safety?

Operating principle zeroing - the transformation of a short circuit to the body into a single-phase short circuit between the phase and the neutral protective conductor, as a result of which the maximum current protection is triggered - fuses or circuit breakers, and automatic disconnection of the damaged installation from the mains is ensured.

When protected by circuit breakers, greater safety is ensured.

What devices are used as overcurrent protection? What is the response time for each device?

The speed of switching off the electrical installation from the moment the voltage appears on the case is 5 - 7 s when the electrical installation is protected by fuses and 1 - 2 s when protected by automatic switches.

On what parameter of the zero protective conductor does the effect depend?the activity of the zeroing action?

What will be the path of the current in the event of a short circuit to the body of a zeroed electrical installation?

What factor determines the speed of protection operation? What value should this factor be according to the requirements of the PUE?

According to the instructions of the Electrical Installation Rules (PUE), the short-circuit current must be at least 3 times the rated current of the fuse link or circuit breaker release.

Based on the results of the research, name the factors thaton which the effectiveness of the zeroing action depends.

From short-circuit current, which must be at least 3 times the rated current of the fuse link or circuit breaker release.

For what purpose should the zero protective conductor have a repeatedgrounding?

To reduce the risk of electric shock that occurs in the event of a break in the neutral protective conductor RE and the phase is shorted to the installation case behind the break point (Fig. 4), the neutral protective conductor must be re-grounded.

What reduces the risk of electric shock when the neutral protective conductor is broken, which has re-grounding?

.

In the event of a break in the neutral protective conductor, which has a repeatgrounding, when shorted to the case, what will be the current path? Why notcurrent protection works?

If the zero protective conductor is re-grounded, then when it breaks, the current circuit through the ground will remain, as a result of which the voltage of the zeroed electrical installations located behind the break will drop to approximately 0.5 U . Therefore, re-grounding significantly reduces the risk of electric shock when the neutral protective conductor is broken, but cannot completely eliminate it.

Why is it forbidden to install in a zero protective conductorfuses, switches, switches?

In the zero protective conductor, it is forbidden to install fuses, circuit breakers and other devices that can violate its integrity.