Why does the phase disappear and what to do in this case

Imagine that you came home and turned on the light - the lamp did not light up, after which you found that there was no voltage in the outlet, while the machines or plugs were intact and turned on. Further inspection may show that phase or zero has disappeared in the circuit. In this article, we will consider why this can happen and what to do if there is no phase on the switch, in the socket, or on the chandelier.

Reasons for the lack of phase

It should be said right away that the phase disappears for one single reason - there is no contact. It doesn’t matter if the cable is broken or the disconnector is open at the transformer substation. Moreover, everything is said for a three-phase and for a single-phase network.

Also, not everyone knows that a single-phase 220V network is one of the phases of a three-phase network with a linear voltage of 380V, and between the phase and zero in this case it turns out 220V. Let's look at what to do if the phase has disappeared using different situations as an example.

Lighting does not work

If there is no light, but the sockets are working, first check the voltage in the lampholder cartridge. In this case, you can check the presence of phase with an indicator screwdriver, but be careful - it is likely to make a short circuit. About, how to use an indicator screwdriver, we told in a separate article.

Check cartridge connection

If there is nothing there, there may be a problem in connecting the wires to the cartridge, if everything is in order with this - then, most likely, the phase in the switch or junction box has disappeared.

Poor junction box

This often happens when the switch contacts seem to close, but there is no connection between them, and also if the wires were poorly clamped in the terminal block of the switch. To check the circuit breaker, you need to remove it from the wall and ring if the contacts are closed when the circuit breaker closes, and at the same time check whether the voltage comes to it.

Light switch test

If there is no voltage at the switch, the problem is in the junction box or in the wiring between it and the switch. If the phase disappears when the light is turned on - you have short circuit in a cartridge, lamp, or on the line from the switch to the lamp.

The outlet does not work

In sockets, the phase can also disappear. This is easy to verify if you remove the non-working outlet and inspect the quality of the connections to the wires. If the connections are good, then you need to know how the sockets are powered. In total, two connection schemes are distinguished:

  1. A train.
  2. A star.

A loop is when each next outlet is connected to the previous one in parallel, and a star is when a separate line goes from each outlet to the electrical panel or junction box.

Outlet wiring diagrams

Then in the first case, you need to check the status of the terminal blocks and contacts in the previous working socket, and in the second case, inspect the junction box.

Terminal extension

In one room

If there is no phase in one of the rooms, pay attention to the electrical panel.If each room is switched on by a separate machine, the machine may have been knocked out to this room, or it may have failed. In the first case, look for problems in the wiring of the room, and in the second, replace the machine.

Emergency state of machine terminalsIf all rooms are powered by one circuit breaker, then the problem is in the junction box from which this room is powered.

There is no light in an apartment building

If you find that the problems with the supply of electricity are not only for you, but also for all the neighbors in the riser, it means that one of the three phases has broken off either in the input electrical panel of the house or in some of the access panels. This happens when burning off zero and phase imbalancewhen, due to overvoltage, the load and its currents are unevenly distributed between consumers. As a result, the contacts of one of the compounds cannot withstand and burn out.

The effect of burning zero

In this case, you can’t fix the malfunction yourself, you need to contact the management company or the supplying organization so that they send the electricians on duty.

Less commonly, two phases disappear. In this case, as in the previous ones, you need to check the status of the circuit breaker terminals on your apartment panel and, if all the contacts and terminals of the circuit breakers are outwardly serviceable in it, call a team of electricians.

Self-troubleshooting in the access control panels is dangerous because you cannot fully disable all lines and hang up prohibition posters.

In a private house

If you find that the voltage in the network has disappeared, look at the input machine, if it is knocked out, turn it on. If after turning on the machine the voltage did not appear - the problem is in entering the house. Loss of contacts on the machine is also possible. And if, when turning on the machine, it immediately knocks it out - there is definitely a short circuit either in the wiring, or in some of the connected devices.


For an electric motor, the operation mode on two of the three phases is emergency and extremely undesirable. Also, in three-phase networks, due to the disappearance of one of the phases, the load uniformity of the transformers and the network as a whole is violated. For a three-phase electric stove, this mode of operation is not so dangerous - some burners simply will not work for you. All this leads to increased current in the neutral wire, its possible combustion and further development of emergency situations.

In conclusion, I would like to note that the solution to the problem of lack of voltage in the apartment or on a specific line essentially consists in checking all the connections and switching equipment of this line. There are only two reasons for it - either a phase imbalance, or a burnout of the conductor due to poor contact or increased load. We strongly recommend: when working in wiring, turn off the power and, if possible, work in attorneys dielectric gloves. Do not interfere with access panels and electrical networks - it is better for electricians to do this from the organization on whose balance this network lies.

Now you know the reasons why there is a situation when there is no phase on the light switch, outlet or on the chandelier itself. We hope the tips we provided help you solve your problem!

Related materials:

(3 votes)

Add a comment