What is the danger of an interruption of the neutral wire in the mains?
Types of damage
On the riser porch
To begin with, in general terms, consider what the electric network of an urban multi-storey building represents. The power source in this case is a transformer substation, from which wires are stretched to the main switchboard of the building. The voltage in the main shield is three-phase, that is, a network of 380 volts. From here, groups of wires to each apartment are already derived. In the apartments themselves, the network is already single-phase - 220 V. If a common zero break occurs on the riser of the entrance, this can cause the failure of household appliances. This leads to inequality - in a three-phase power circuit, phase imbalance and instead of a symmetrical load, an asymmetric load forms in the four-wire circuit.
In simple words, this can be explained as follows: from the main panel at the entrance to each individual apartment the same voltage is applied - 220 V. If there is a break in the zero wire, it can happen that 300 volts go to one apartment and 170 volts to the other (as an example). The result - overvoltage and "undervoltage" will cause electrical appliances to fail. Usually, if zero damage occurs, equipment with an engine breaks down: washing machine, refrigerator, air conditioning, etc. In addition, a fire may occur, even worse.
Inside the living room
The very opposite situation can happen when zero breaks in a single-phase 220 Volt network, that is, inside your apartment, private house or in the country. In this case, the consequence may be a person's electric shock. This happens because in the outlet you will have the same phase on both terminals. Now we will tell you what caused the appearance of the so-called second phase.
From your input shield, the current passes through the phase wire, and since most consumers of electricity are constantly connected to the network (the same chandelier), when the circuit breaks, the voltage will switch from phase to zero. Result - an electric current will be present in the two holes of the outlet. But this is not the worst thing, because The main danger is that electric shock can occur from any equipment. The reason for this is the wrong grounding system of the network in the apartment or house. If you connect the “ground” in the switchboard to the zero bus (which cannot be done), when you touch the grounded housing of household appliances, you will immediately be shocked. The consequences, as you know, can be dire.Immediately we bring to your attention the correct option for protection against a zero break in the house - a network with grounding system TN-S:
To summarize the consequences of a zero break in a three-phase and single-phase network, the following should be noted: if the neutral wire is damaged in the riser, the danger spreads to household appliances, and if the working zero is damaged in the apartment itself, the threat will spread to you.
To see what can happen if the zero core breaks, you can in this video:
How to identify a hazard?
To find the place of damage to the neutral wire, you can use a special tester that can accurately show where the break occurred even under the walls, as shown in the photo below (if the wiring is hidden). About, how to find a wire in the wall, we told in the corresponding article.
Another search option is a visual inspection of the entire circuit. View all wire connections in the switchboard. Perhaps zero burned out on one of the machines, which is not difficult to determine and eliminate. If the breakage of the neutral wire occurred on the riser of the staircase, then it’s not your business and the housing and communal services or a special service that they will call to inspect the power transformer and secondary circuit including will troubleshoot.
How to protect home wiring?
To protect the household electrical network from an open circuit, you need to use special devices: monitoring relays and voltage limiters. We recommend that you connect these devices to the input shield to protect yourself from adverse effects.
Causes of the phenomenon
Well, the last thing I would like to talk about is why there is a zero break in the apartment. There can be many reasons, but the most real, judging by the comments on the forums and personal experience, we can distinguish:
- Burning of the neutral wire at power surge or short circuit.
- Poor connection lived or poor contact.
- Mechanical damage to the line by the elements (for example, in strong winds) or by carelessness of a person during repair work.
- The wiring is old and the wires are simply exhausted by time.
- Theft or malicious intent (sometimes this happens).
So we examined the types and consequences of a zero break in a three-phase and single-phase network, as well as ways to protect against this phenomenon and tips for troubleshooting. If you do proper grounding in a private house, and also protect the wiring with special devices, then when the zero breaks, no ills will happen!