what is the difference between neutral and ground and got the best answer
Answer from Cat Obormot[guru]
The neutral wire goes to the power source, the ground wire is connected to the planet of the same name.
There are power circuits in which the zero is connected to ground (grounded neutral),
and circuits where the zero is not connected to ground (circuit with an isolated neutral).
Answer from Tosha[guru]
No
Answer from Olya[active]
Grounding can be considered as a specific type of grounding.
Answer from Mikhail Levin[guru]
zero is the wire through which current flows. (In a regular socket, one wire is zero, the other is phase).
The ground is a separate wire, grounded and running without any interrupters along the way. Used for grounding device housings (refrigerator computer, washing machine).
IN normal conditions the potential of zero and ground is 0. That is, there is zero resistance between them, in fact it is one and the same.
But this is only in normal cases.
If you have a large load, such that the voltage in the network drops, zero no longer coincides with ground. In my house, if you plug in a couple of heaters in the rooms, a washing machine, a microwave and a kettle, the volt remains 180. In this case, the phase relative to the ground “drops” to 200, and the zero rises to 20 (just measure the 0-heating battery with a voltmeter.
It’s even worse if something burns in the pipeline. If the neutral wire burns/falls off, all the insides of the devices will be under voltage of 220 volts. This is where the “ground” comes in handy - it won’t burn out, nothing is connected to it, and the body of the same washing machine won’t kill you.
And in our old houses, idiots even hung plugs on both wires. As a result, if the plug is triggered at zero, all the devices are out of phase, and there is darkness in the apartment...
Answer from Oleg[guru]
GROUNDING FOR THE PROTECTION AND SAFETY OF THE USER. ,
and ZERO is like a channel for incoming energy.
Answer from Shark[master]
zero - a constant output for electricity exists for a stable electrical load. chain
grounding - output for excess (external from the circuit) electrical flows. current, unlike zero, exists for a stable load so that there are no electrical fluctuations. current.
If we consider low-current networks (up to 1 kV), then grounding can be neglected (use zero, since in such networks drops do not pose a danger to the circuit and are eliminated with the help of section stabilizers), but on energy carriers (over 10 kV) grounding is indispensable. because you can turn into a shish kebab.
Answer from Edward[guru]
zero is a number, and grounding is a process))
Details
Zeroing - will it protect or kill?
Hello, friends!
In this article we will talk about what zeroing is, where it is used, as well as the main errors in its design. The topic is not easy, and there are constant debates on forums.
It is interesting that often even electricians cannot correctly say how grounding differs from grounding. Let's figure it out. First, let's see what the PUE says about zeroing.
Grounding in electrical installations with voltages up to 1 kV is the intentional connection of parts of an electrical installation that are not normally energized with a solidly grounded neutral of a generator or transformer in three-phase current networks, with a solidly grounded output of a single-phase current source, with a solidly grounded midpoint of the source in direct current networks.
Simply put, grounding is the connection of the body electrical appliance with neutral wire.
Now let's see what the PUE tells us about grounding
Grounding of any part of an electrical installation or other installation is the intentional electrical connection of this part to a grounding device.
In simple words, grounding is the connection of the body of an electrical device with a ground electrode. A ground electrode is a structure made of metal pins driven into the ground.
Now let's look at how the most common power supply systems for apartment buildings work.
old, Soviet system TN-C
More modern system TN-C-S
Both schemes use a combined neutral conductor PEN, which is grounded at the transformer substation.
The main difference between them is that in TN-C-S the combined conductor is divided into a working zero and a protective conductor. This is done in the introductory common building panel (ACB). In this case, re-grounding must be done.
If you look closely at the diagrams, it becomes clear that the working zero is always connected to ground, that is, grounded. And the question arises: what, exactly, is the difference between grounding and grounding? After all, by connecting the body of the device to the working zero, we actually connect it to the ground.
In fact, there is a difference. It lies in the principle of action.
Grounding is designed to drain current to ground. This reduces dangerous voltage on the body of the device or device.
Grounding is intended to create a short circuit effect during phase breakdown on the housing. At the same time, the machine is activated and turns off the emergency line.
Thus, grounding and grounding in TN systems work simultaneously, so to speak, in one bottle. Therefore, the 3rd protective contact in Euro sockets in TN systems is both grounding and neutralizing.
Based on this, it is correct to talk about a combined conductor PEN, a working neutral conductor N and a protective conductor PE. At the same time, even electricians do not always understand the difference between PE and N, but it is very significant.
Usually, when some “electrician Uncle Vasya” talks about grounding, he means various kinds of collective farms such as jumpers in sockets and the like connecting the protective wire to the neutral wire. And it's dangerous.
Incorrect zeroing can, instead of protection, cause a tragedy. And such pseudo-protection occurs very, very often.
Let's figure out how protective grounding is done correctly and what absolutely should not be done.
Remember, the division of the combined conductor into a working zero and a protective zero must be done in a common house input device (IDU). And from there the protective conductor must go to the floor panels, and from them to each apartment.
Thus, we get a five-wire riser: 3 phases, working zero and protective zero. In this case, we are not talking about the so-called grounding, since each apartment receives a separate protective wire (TN-C-S and TN-S systems). It needs to be connected to the third contact of the sockets.
In old houses with non-modernized wiring, there is usually a four-wire riser: 3 phases and a combined neutral PEN (TN-C system). This is where the complete chaos and terrible mistakes begin.
It all starts in the floor panel. Often it makes an independent division of PEN into PE and N.
This option has the right to life, but only if important rules. Here are the main ones:
Rule 1. In single-phase circuits, it is prohibited to separate the neutral wire (PUE - 1.7.132).
How to determine which network is in your home? In relatively old houses, the access risers are four-wire: three phases and one combined zero (PEN). That is, three-phase risers are used, respectively a three-phase circuit.
In very old houses, Stalin and Khrushchev buildings, a two-wire riser is often used, in which there is only a phase and a working zero. Distinctive feature such houses - the absence of access panels. The risers go in the shafts between the apartments, and in the apartments themselves there are specific “humpbacked” shields. In such houses, as a rule, a single-phase network is used.
Rule 2. The combined PEN conductor must have a cross-section of at least 16 mm for aluminum or 10 mm for copper.
That is, the zero riser must have a cross-section no less than the specified one. In many houses the cross-section is smaller; in this case, it is impossible to divide the combined zero into protective and working. If you have a Soviet-built house with gas stoves, then in 80% of cases the riser in it is weak.
Rule 3. Once PEN is separated into PE and N, they cannot be recombined.
Here, I think, no explanation is needed.
Rule 4. The protective conductor PE must not be disconnected.
That is, you cannot install machine guns and other disconnecting devices on it.
Rule 5. You need to separate PEN BEFORE all machines, switches, switches.
It’s better to do this: take a brass busbar and screw it to the shield so that there is contact between them. Make a branch from the zero riser through a separate nut to this bus. Connect the PE protective wires from the apartments to the bus.
If at least one of these rules is not followed, then it will not be protection, but a life-threatening collective farm.
A little more about what not to do
1) Connect the protective and neutral contacts in the socket with a jumper. This is one of the most dangerous mistakes!
If the zero burns out, is damaged, or is accidentally disconnected, dangerous phase voltage will immediately appear on the housing of all devices connected to such sockets. In this case, neither the RCD nor the machine will work. Hello death.
The same effect will occur with a random change of phase and zero.
2) Place the neutral and protective conductors on one screw in the shield
PE and N must be on different terminals (busbars). Moreover, each wire from a separate apartment must be clamped with a separate screw.
3) Zero to an ungrounded (non-zeroed) shield.
Typically, all panels have direct contact with the zero or protective riser (zeroed). But sometimes there is no contact, for various reasons. For example, the connecting wire fell off. Grounding such a shield can lead to the appearance of dangerous voltage on its body.
In practice, this kind of jambs are found all the time, in various options and combinations. I can advise you not to be lazy, study the PUE, and also not trust your wiring to dubious individuals.
For safe work on various electrical installations and conductors, a connection of open metal taps to the ground and a network connection to a neutral cable are used. But few novice craftsmen know exactly the difference between grounding and neutralizing electrical installations and electrical equipment.
Definition of grounding
Grounding is the deliberate connection of exposed parts of electrical equipment that are energized to a special ground tap, busbar or other protective equipment. This could be reinforcement in the ground, part of an electrical installation or other devices. This approach, according to the PUE, is a mandatory measure of deliberate protection of both residential and non-residential assets. This is also stated in the rules and requirements of GOST 12.1.030-81 SSBT (electrical safety and system of occupational safety standards).
Photo - diagramIn almost every modern house a TN-C-S or TN-S grounding scheme is installed. But in buildings old building There is often no grounding at all, so apartment owners in such buildings have to organize the ground on their own. This system is called TN-C. This is done by connecting the tap to the grounding loop, which can be located directly in the ground near the building or near the transformer booth.
Figure TN-C
Theoretically, such a wiring upgrade could be organized by a special installation company, but this is rarely practiced. More often to the panel on the floor (in apartment building) the ground is supplied, and the remaining wires are connected to it.
- If a phase hits an open metal tap of any electrical device, then voltage appears in it. The same happens if, for example, the cable insulation is broken. The human body is an excellent conductor of current; if you touch such a tap, you will receive a strong electric shock. Grounding will help avoid this;
- Stray currents go into the grounding conductor, this guarantees life protection;
- Particularly dangerous is the voltage that reaches heating radiators. In this case, all batteries in the house become current conductors. But if the ground is installed, then all the voltage will go through the conductor.
Photo - land version If it is not possible to establish a full grounding circuit, then other methods are used. For example, it is now very common to connect portable grounding pins (portable busbars). Their operation is no different from a standard stationary outlet, but at the same time they are much more practical in their functionality.
Photo - portable splint Zeroing purpose
Grounding and grounding are sometimes confused with each other, so what is the difference between the two? Zeroing is applied according to the PUE only for industrial installations and is not a guarantee of safety. If a phase hits the open part of the device, then the current does not flow out. After this, the two phases are coupled, and, as a consequence, short circuit. The neutral conductor is necessary for the rapid response of a differential circuit breaker to a short circuit, but not to protect a person from electric shock. Therefore, it is customary to use it only in production, where a quick power shutdown is required in case of an emergency.
Photo - zeroing diagram Is it necessary to do grounding in a private house or apartment? No, this is not necessary, and is even fraught with various negative consequences. Say, if the neutral wire burns out, then large quantity electrical devices, to which it was connected will break due to the extremely high voltage surge. It is worth remembering that your safety will not suffer if, along with grounding, you also arrange grounding, install an RCD and a safety switch.
Photo - the principle of zeroing How to set the grounding so that the device connected to it does not burn out:
- You must use three-core insulated wire. One core is allocated for phase, the second for zero, the third for grounding;
- Ground connects at the very end electrical installation work to the body of the safe conductor to the grounding loop, etc. The most practical is a special grounding tap at the switchboard;
- For safety reasons, be sure to install various switches power supply and other protective installations.
Video: what is the difference between grounding and grounding
Main difference
The most important thing to remember is that grounding and grounding circuits have different protective effects. Zero guarantees a quick response to potential changes or current leakage for protection installations. Accordingly, at high voltage, all energy consumers are switched off: lighting fixtures, computers and other machines (including machine tools, transformers).
Photo - the difference between grounding and grounding Grounding ensures potential equalization and protection against electric shock. Earth is more often used at home; its installation can be easily done with your own hands. But there is no guarantee that the fuses will quickly respond to a leak. The best option to increase the safety guarantee is the combined use of grounding and grounding of networks and open parts of machines.
Before installing any of these protection options, you must obtain permission to carry out the work. Additionally, the protective conductor is calculated, earth is connected to each consumer in the home, and protective equipment is installed.
If you independently organize the power supply for your apartment, office or garage, this means that the responsibility for safety also lies with you. To protect electrical networks and your health (and sometimes life), grounding and grounding are used.
In what cases is protection required?
When there is physical (more precisely, electrical) contact with the body of a phase conductor, or a circuit element to which voltage is currently applied, two dangers arise:
The system of grounding and grounding of electrical equipment provides protection against the considered hazards, or at least minimizes the consequences. Many inexperienced home-grown electricians confuse these two concepts. Or they deliberately use the working zero when organizing grounding.
This is especially true in old high-rise buildings, where a separate grounding loop is not provided. If the power supply lines are fully operational, this is not so dangerous. However, if damaged neutral wire
on the highway, or deterioration of contact at the terminal connections, the working zero loses electrical connection with the real “ground”.
You rely on phase protection and work with an electrical appliance without fear. At a critical moment, the protection does not work, and in the best case, equipment damage occurs, and in the worst case, a fire or electric shock occurs.
Important! Using a working zero to protect users is prohibited!
- Protective grounding and grounding are fundamentally different in the way they are connected to the physical ground. If you use zero as grounding, troubles can occur:
- For example, you grounded the boiler to working zero. In the event of a phase breakdown on the housing, the residual current device (RCD) may not operate. Through water, from a hot tap, tension is transferred to you. If you are in the bathroom, you will be exposed to a life-threatening electrical current; You are using an electric stove located next to the radiator. Feeding system hot water
The main requirement for any electrical household appliance is safe operation. This is especially true for equipment in contact with water. With absence additional protection even a small problem with electrical wiring (burning through the insulating layer, a hole between the turns of the motor) is dangerous. Electric potential appears on the body of the faulty device. In this case, a person or animal who touches the body may receive an electric shock. To avoid this, protection methods such as grounding and grounding have been developed.
Grounding tasks
The artificially created contact between the electrical installation and the ground is called grounding. Its task is to reduce the voltage on the device body to a level that is safe for living beings. In this case, most of the current is diverted into the ground. For a grounding system to work effectively, its resistance must be significantly lower than that of the rest of the circuit. This requirement is based on the property electric current
always choose the least resistance in your path.
Note! Grounding is used exclusively in electrical networks with an isolated neutral.
The fault current is sometimes insufficient when using a ground electrode with a relatively high resistance for the response of protective devices. Therefore, another task of the grounding system is the increase in emergency fault current.
- Types of grounding devices: Lightning protection. Retracted impulse currents
- , entering the system as a result of lightning strikes. Used in lightning rods and arresters.
- Workers. Designed to maintain normal operation of electrical installations. Used in both normal and emergency situations.
Protective. They protect people and animals from electric shock passing through metal objects in the event of breakdown of phase conductors.
- Grounding devices can be natural or artificial: Natural include hardware
- , the main function of which is not to drain current to the ground. Such grounding conductors include pipelines, reinforced concrete elements of buildings, casing lines, etc.
For the grounding system, you cannot use pipes intended for transporting flammable substances (both gases and liquids), aluminum parts, and cable sheaths. Objects coated with an anti-corrosion insulating layer are also not suitable for this purpose. It is prohibited to use water supply and heating pipes as grounding conductors.
Technical design of grounding systems
There are several connection schemes with different composition protective and working conductors:
- TN-C;
- TN-C-S;
The type of grounding is indicated by the first letter in the designation:
- I - current-carrying elements do not touch the ground;
- T - the neutral of the power supply is grounded.
The method of grounding open conductors is determined by the second letter:
- N - direct contact between the grounding point and the power source;
- T - direct connection with the ground.
After the hyphen there are letters indicating the method of functioning of the protective PE and working N neutral conductors:
S - the operation of the conductors is ensured by a single PEN conductor;
C - there are several conductors.
TN system
Grounding of the TN variety includes subsystems TN-C, TN-S, TN-C-S. The oldest of these subsystems, TN-C, is used in 3-phase four-wire and 1-phase two-wire electrical networks. Such networks are usually found in old buildings. Despite its simplicity and relatively low cost, the system does not provide sufficient level safety, and therefore is not used in new buildings.
The TN-C-S subsystem is used for renovation of old buildings. It is relevant where the working and protective conductors are combined at the input. The use of TN-C-S is necessary for system renovation when computer or telecommunications equipment is installed in an old building. This grounding is transitional type between TN-C and the most modern subsystem - TN-S. TN-C-S is a relatively safe and financially accessible grounding scheme.
The difference between the TN-S subsystem and other types of such equipment is the location of the working and neutral conductors.
They are installed separately, while the neutral protective PE conductor combines all the existing conductive elements of the electrical installation. To avoid duplication, create a transformer substation equipped with main grounding. An additional advantage of the substation is the ability to reduce the length of the conductor running from the cable entry into the equipment to the ground electrode.
TT system In this grounding system, current-carrying are in direct contact with the ground. In this case, the electrodes do not depend on the grounding device of the substation neutral. TT is used when, for technical reasons, it is not possible to build a TN system.
IT system
In this system, the neutral of the power supply does not touch the ground or is grounded using a high-impedance electrical installation. The circuit is popular in situations where it is necessary to connect sensitive equipment (hospitals, laboratories, etc.).
Zeroing
The process of zeroing consists of combining metal elements, not under voltage with a grounded neutral of a step-down 3-phase current source. A grounded terminal of a 1-phase current generator is also used. Grounding is used to provoke a short circuit in the event of breakdown of the insulating layer or penetration of current into a non-current-carrying element of the equipment. The meaning of a short circuit is that after this the circuit breaker is triggered, the fuses blow, or other protective measures are turned on. Zeroing is used in electrical installations with solidly grounded neutral.
If you install a residual current device on the line, it will trip due to the difference in current strength between phase and zero. A circuit breaker installed in addition to the RCD will allow both devices to operate in the event of a breakdown or to connect the fastest connecting protection element.
When installing the grounding, it should be borne in mind that a short circuit should lead to melting of the fuse or tripping of the circuit breaker. If this does not happen, the free flow of the fault current through the electrical circuit will cause voltage to appear on all neutralized objects, and not just at the site of the breakdown. The voltage indicator is the product of the zero resistance and the circuit current, which is very dangerous when a living creature is shocked.
It is necessary to carefully monitor the good condition of the neutral conductor. When it breaks, voltage appears on all neutralized elements, since they automatically come into contact with the phase. For this reason, it is prohibited to install any protective devices (other than switches and fuses) on the neutral conductor, due to which a break occurs when triggered.
To reduce the risk of electric shock when the neutral conductor breaks, every 200 meters of the line are created additional grounding, as well as on the end and input supports. The resistance level on each new ground electrode should not be higher than 30 Ohms.
The difference between grounding and zero
The main difference between grounding and neutralizing is the purpose of the systems. Grounding is needed to quickly reduce the voltage to an acceptable level. The task of grounding is to completely turn off the current in the area where a breakdown occurred on the housing or other non-current-carrying element. Zeroing is associated with a decrease in the potential of the housing during the period between the circuit and the power supply being cut off.
Grounding is not used in new buildings. In new buildings, a 3-wire cable with phase, neutral and ground is laid (1-phase system) or a 5-wire cable (three phases, neutral and ground) in a 3-phase system. The most commonly used circuit is TN-S, but TN-C-S is also found.
Is it necessary to ground in an apartment?
It is not worth using grounding in order to protect residents and electrical installations in the apartment - there are situations when a refrigerator (or other device) is grounded, and a current breakdown occurs. Incorrectly performed electrical installation is also common (the electrician could have mixed up the wires and connected a phase instead of zero). In such cases, household appliances fail even before the circuit breaker operates.
Installation of a residual current device, differential machine or circuit breaker is only necessary together with grounding.
Requirements for grounding and grounding
All electrical installations and circuits equipped with neutral wire insulation require the installation of a protective system (grounding or grounding).
There are several rules that should be followed when creating a protective system:
- Grounding must be done for installations with a solidly grounded conductor with a power of up to 1000 volts. Grounding is not done in such systems.
- Grounding should be provided with a 380 volt transformer. In a neutralized system, the secondary voltage should not exceed 380 volts, and the step-down voltage should not exceed 42 volts.
- When zeroing, connection from the separating transformer to only one electricity consumer is allowed. Current rating protective device- up to 15 amperes. Grounding or grounding of the secondary winding is not allowed.
- When grounding zero in a 3-phase electrical circuit, it is necessary to install protection against current breakdown. Mount it in the neutral conductor or phase from the lower voltage.
- Protective grounding or grounding must be created in outdoor installations, as well as in special hazardous conditions work. The voltage rating is 42 volts ( alternating current) or 110 volts (DC).
- For voltages above 380 volts (DC) and 440 volts (AC), protection is required regardless of other conditions.
The following are subject to grounding:
- electrical installation housings;
- equipment drives;
- frame parts and metal structures of distribution cabinets and switchboards;
- secondary transformer windings;
- steel cable sheaths;
- busbars;
- cables;
- metal pipes for wiring;
- electrical equipment installed on moving elements.
As for housing, grounding and grounding are necessary for electrical household appliances with a power of more than 1300 watts.
Metal products such as bathtubs and shower trays, suspended ceilings are subject to grounding to equalize potentials. To ground air conditioners, electric stoves
or similar consumers of electricity with a power of over 1300 watts use a dedicated conductor. It should be connected to the mains neutral.
Note! The cross-sections of the phase and neutral conductors must be the same.
A detailed list of electrical installations that require protection by grounding or grounding is specified in the Electrical Installation Rules. The PUE is an official document; all standards are specified in it. The document also establishes a list of equipment for which protection is optional.