A malfunction in which two phases are immediately detected in the outlet is a common phenomenon in household practice. Only an experienced specialist who knows electrical matters can find its cause. However, with a competent approach, it is possible to independently solve the problem. To do this, you need to familiarize yourself with the principles of the formation of the supply voltage, which is supplied to each consumer via electric networks.
Normal distribution of potentials in sockets
Before you understand why there are two phases in sockets at once, you should know that a pair of supply conductors is supplied to the apartment through the electrical wiring line, one of which is called phase, and the second is zero. The potential of 220 Volts acts only on one of the terminals of the sockets, and on the second it is equal to zero. You can verify this if you use a conventional indicator screwdriver.
The presence of two potentials (phase and zero) is a prerequisite for the operation of any power supply system.
If there is no one phase in the outlet or for some reason zero has disappeared - you will not be able to get the difference of their values (220-0 = 220 Volts), called voltage. Therefore, if zero disappeared in sockets, and it is not known how to find it, you should familiarize yourself with the principle of potential formation before starting a search. The situation is much more complicated when, instead of zero, another phase appears on the second terminal. To eliminate this malfunction, you need to understand the causes of its occurrence.
The causes of the appearance of two phases
The appearance of a phase on two wires at once can be explained by the following set of circumstances:
- A broken wire in the input panel of a house or apartment.
- Its damage is at the input or inside the junction box.
- Contact break in the “zero” connection in only one outlet.
- Shorting the phase wire to the zero core due to insulation damage.
To understand why the indicator shows the phase at once on both wires, the reason that caused each of these phenomena will need to be considered separately.
If there is no zero in the outlet, first of all, you should find the place of its disappearance (break). A possible option is damage to the cable at the entrance to the house or apartment, as a result of which the “zero” will disappear in all outlets installed inside the building and in separate rooms. In addition, the contact may be broken anywhere in the electrical circuit, including at the input or inside the junction box, which will lead to malfunction of only a few outlets.
The second case concerns those of them that are connected within this room to this particular distribution unit (that is, about half), and in all other installation products the normally working “zero” will be preserved.
If there is a malfunction only at the input to a specific outlet, the disappearance of zero and the appearance of the second phase will be observed only in it. In order for the situation under consideration to form completely - the voltage fell on the dangling zero contact - it will be necessary for the bare phase wire to accidentally close on it.
A variation of the latter case is the option when the zero core is not broken, and the phase wire with damaged insulation is closed to ground contact. This will also lead to the appearance of two high potentials in this outlet at once.
Possible consequences and danger of two phases
When there are 2 phases in a particular outlet at once, it is necessary first of all to worry about how this threatens the people who use it. This situation is unacceptable for the following reasons:
- The potential difference between the terminals of the outlet will be 220-220 = 0 Volts.
- The voltage will drop, connected household appliances will not work.
- There is a danger due to the disappearance of the protective earth circuit, which in old houses acts through an earthen conductor (due to the lack of a local circuit).
In this case, there is no need to talk about any protection at all, the consequences may be unacceptable to people. An ignorant electrician, considering that as regards the neutral wire (in blue insulation), may be under high voltage. Therefore, it is prescribed in the normative documentation when disassembling the installation products that it is necessary to check by means of an indicator that there is no phase on both terminals.
In this situation, all or only light switches connected to this distribution box will also stop working. This is explained by the fact that a phase potential appears on the neutral wire connected to the chandelier connected to the corresponding contact of the socket, and the voltage difference becomes equal to zero.
Troubleshooting Tips
If two high potentials (2 phases and a grounded zero - for new installation products with three contacts) act on the terminals of the sockets of the old model - this situation requires urgent intervention. Since it is associated with a break in the zero core, first you need to find the exact location of the damage using visual inspection methods plus the necessary tool. To do this, you will need to take actions depending on the nature of the damage.
When the problem concerns all the outlets of the living rooms of the entrance or a certain apartment, you should call an electrician who has access to the distribution cabinet and the opening machine. If the malfunction is observed only in the apartment (on one / several junction boxes or in a separate outlet), it is possible to fix it independently. To do this, you need to do the following operations:
- Disconnect the introductory machine located in the common corridor and supply voltage to the entire apartment.
- Inspect the distribution box, at the input of which, or inside, a malfunction is allegedly hidden.
- If you find an obvious break (bad contact) of the incoming or outgoing wires from the box, you must restore the broken circuit using the simplest tool - a soldering iron or a screwdriver.
- If a malfunction occurs only on one of the outlets, remove its cover and carefully examine all the contacts.
- If a loose fastener is found on the zero terminal, tighten it using a screwdriver.
In order for the second phase to disappear and the chandelier to start burning again, it will also be necessary to isolate the damaged phase core from the already restored “zero”.
Only if you follow the relevant instructions can you eliminate the detected malfunction observed in all, half or only one outlet. The appearance of two phases, regardless of the total number of outlets involved, most often occurs when the rules for using household electrical products are violated.
