What is the danger of an open circuit in the mains?

Types of damage

On the riser entrance of the

To begin with, in general terms, we will consider what a power grid of a city high-rise building is. The source of power in this case is a transformer substation, from which the wires are stretched to the main switchboard of the building. The voltage in the main shield is three-phase, that is, 380 volts. From here, the groups of wires for each apartment are already displayed. In the apartments themselves, the network is already single-phase - 220 V. If there is a breakdown of the total zero on the standpipe, this could cause the outage of household appliances. This leads to an inequality: in a three-phase power scheme, a phase skew occurs and instead of a symmetrical load, an asymmetric one is formed, passing through a four-wire circuit.

In simple words, this can be explained in the following way: from the main flap in the entrance to each individual apartment is supplied the same voltage - 220 V. If there is a breakdown of the zero wire, it can turn out that one apartment will receive 300 volts, and to another 170( as an example).The result is overvoltage and "undervoltage" will cause the electrical appliances to fail. Usually, if there is a zero damage, the technique that has an engine breaks: a washing machine, a refrigerator, an air conditioner, etc. Besides this, a fire can occur, which is even worse.

Inside the premises

Quite the opposite situation can occur when a zero is cut off in a single-phase 220 volt network, that is inside your apartment, private house or at the cottage. In this case, all the equipment will work, as it did before, but the result can be a person's electric shock. It happens because in the outlet you have not one phase but two. Now we will tell you what caused the emergence of a two-phase power network in the apartment.

From your input shield the current passes through the phase conductor, and since most electricity consumers are permanently connected to the network( the same chandelier), the breakdown voltage will go from phase to zero. The result - in the two holes of the socket there will be an electric current. But this is not the worst, becausethe main danger is that an electric shock can occur from any technique. The reason for this is an incorrect system for grounding the network in an apartment or house. If you connect the "ground" in the switchboard to the zero bus( which can not be done), when you touch the grounded housing of household appliances, you will immediately be shocked. Consequences, as you understand, can be deplorable. Immediately, we present to you the correct version of the protection against a ground fault in the house - a network with a grounding system TN S:

Summarizing the consequences of a zero-point in a three-phase and single-phase network, the following should be noted: if the zero wire on the riser is damaged,household appliances, and if the worker zero is damaged in the apartment, the threat will spread to you.

To see what can happen if the zero core is cut off, you can on this video:

fault How to identify the danger?

To find the fault location of 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 the wire in the wall, we told in the relevant article.

Another search option is visual inspection of the entire circuit. Review all wiring connections in the switchboard. Perhaps, zero was burnt on one of the machines, which is not difficult to determine and eliminate. If the break of the zero wire occurred on the riser, it's not your business, and the troubleshooting will be done by the housing and communal services or a special service that they will call to inspect the power transformer and the secondary circuit including.

How to protect the home electrical wiring?

To protect household electricity from the breakage of the neutral wire, you need to use special devices: monitoring relays and voltage limiters. We recommend that you connect these devices on the input shield to protect yourself from adverse effects.

Reasons for the phenomenon

Well, the last thing I would like to talk about - why there is a breakdown of zero in the apartment. The reasons can be many, but the most real, judging by the comments on the forums and personal experience can be identified:

1. Burnout of the zero wire in case of a voltage jump or short circuit.
2. Poor connection of conductors or weak contact.
3. Mechanical damage to the line by elements( for example, in strong winds) or by a person's negligence in repair work.
4. The wiring is old and simply wires are tormented by time.
5. Theft or evil intent( sometimes it happens).

Here we have considered the types and consequences of a zero-point in a three-phase and single-phase network, as well as ways to protect against this phenomenon and tips for troubleshooting. If you make the correct grounding in a private house, and also protect the wiring with special devices, then when zero breaks, no trouble will occur!

Also read:

• How to determine the phase and zero without instruments
• Why in the bathroom it beats the current
• What is better to put: a differential or an RCD?