How to determine the ground wire

When installing a socket or other elements of electrical wiring, the need to connect a cable in a junction box, the question arises of how to determine where which wire is of the three available. Where is phase wire, as a rule, it is not difficult to determine - just use an indicator screwdriver for this. The question then becomes: where is the working conductor from the remaining two wires, and where is the protective ground conductor.

If the conductors are not marked, that is, they do not have corresponding tags indicating where which wire is, then for many this becomes a problem. In this case, it is necessary to determine exactly where which wire is, since in case of an erroneous connection, negative consequences are possible - a short circuit or electric shock. Below we will try to answer the question of how to determine the ground wire in home wiring.

What is zero, phase and grounding:

• Grounding - the third wire in a single-phase network (through it the current flows into our apartments), it does not carry a work load, but serves as a kind of fuse,

• Zero (with an open circuit, for example in a socket, there is no voltage on the neutral wire),

• Phase - phase wire through which current flows.

Wire color coding

Cables and wires may have color marking. If the wiring was installed in accordance with all the rules, and each of the conductors of the wiring lines was connected strictly according to the colors that are generally accepted for the phase, zero and ground conductors, then there will be no problems finding where which conductor will arise.

In accordance with the PUE, the working neutral conductor is marked with blue or blue, and the protective grounding conductor with yellow-green striped. As for the phase conductor of home electrical wiring, it can be one of the following colors - white, black, brown, red, gray, purple, pink, orange and turquoise. Manufacturers of cable and wire products can choose one of the following colors for marking the phase conductor.

Another question is whether the connection was made correctly. To be sure that the wires were connected by color correctly can only be done if the wiring was done independently.

In all other cases, it cannot be guaranteed that all wiring lines were connected strictly in color and, therefore, if you need to connect certain elements to the wiring, you cannot focus on the color marking of the conductors in order to avoid connection errors.

In this case, to determine the ground wire, you must use other methods, which we will consider below.

Ground wire detection using a multimeter

When it comes to wiring, first of all, you should remember about safety measures and de-energize the wiring every time when it will be necessary to work with bare cores and other conductive elements. For example, if it is necessary to strip the cores of the cable or connect the cable to an outlet.

So, we have three wires - phase, zero and ground, which are not marked in any way. The phase conductor, as mentioned at the beginning of the article, is easy to determine using an indicator screwdriver. Other conductors can be defined with a multimeter.

We set the multimeter to the range of measuring AC voltage above 220 V. Depending on the type of multimeter, the values ​​of the measured voltage may differ, but in any case you need to choose a limit above 220 V.

We measure alternately between the phase conductor and one of the remaining ones, then between the phase and the other conductor. The larger of the two values ​​is the voltage between the phase conductor and the working zero, respectively, the smaller the voltage will be between the phase and ground conductor.

It should be noted that many electricians advise the considered method of determining the ground and ground wires, without even specifying which grounding system for electrical wiring.

This recommendation regarding the search for ground wire is relevant only. for TT configuration networks, that is, for those cases when the home wiring has an individual grounding circuit, and the neutral conductor of the electrical network is used exclusively as a working neutral wire.

As for the most common in our time network configuration TN-C-S, then for such a network the above recommendation is irrelevant.

This grounding system provides for the separation of the combined conductor into a working neutral and protective conductor directly in the building, that is, in fact, these conductors are electrically connected to each other, from the separation point to the measurement location, approximately the same distance and, correspondingly, the same resistance.

Therefore, in this case, the measurements will show the same voltage value, differences of several volts cannot be a sign that this is a neutral wire or ground.

In TN-S configuration networks, this method is also not relevant. In these networks, the working neutral conductor and the protective ground conductor are divided throughout the mains from the power source to the consumer. The resistance of the wires of the power line is different and, accordingly, the difference in voltage measurements between the phase and the alternating zero and ground conductor is due solely to the difference in resistance.

The method of disconnecting the neutral wire

In order to accurately determine the ground wire in the wiring, you must perform the following manipulations. The first thing to do is disconnect all electrical appliances from the network so that no current passes through them into the neutral wire of the electrical wiring.

Then, in the electrical distribution panel, it is necessary to disconnect the neutral wire by disconnecting it from the input circuit breaker or from the zero bus, from which the zero is branched into other lines. Thus, the entire wiring will have a phase conductor and protective grounding.

We take a multimeter and alternately measure the voltage between the obviously marked phase conductor and two others. In this case, the voltage will only be shown between the phase and ground conductor, which can be immediately marked. There will be no voltage between the phase and neutral conductors, since it is disconnected in the shield. Perhaps there will be a small value, up to a dozen volts - this is the so-called induced voltage.

Wiring proverbial

You can determine the ground wire of a home electrical wiring by conducting calls. This method is relevant for those cases when the location of the zero and ground conductor is known at one end of the cable to be dialed, and there is no marking on the other.

In this case, it is enough to de-energize the wiring and determine the beginning and end of each cable core by the method of checking the integrity of the wires. For example, in the junction box of one of the rooms of the apartment, the phase, neutral and protective conductors are marked, and the cable connected to this junction box does not have any markings.

Before carrying out work, the electrical wiring must be completely de-energized. For dialing, you can use the usual home-made lamp, batteries and wires, or a multimeter in the dialing mode.If the cable length is relatively small, for example, within a room, then wires of the required length can be used to connect to both ends of the cable.

For long sections, for example, from the distribution panel to the outlet of one of the rooms, it is better to use a core known at both ends. To do this, while the wiring is not de-energized, you must use the indicator to find the phase conductor and mark it on both ends of the called section.

After de-energizing the wiring, you should connect one probe of the multimeter (or homemade) to the marked wire, and the other probe to one of the two remaining wires.

At the other end of the called area, we alternately touch two wires to the previously marked wire and, thus, determine the second end of the wire and mark it at both ends.

In conclusion, it should be noted that if there is a need to determine the ground wire, it is better to immediately mark it so that in the future it would not be necessary to repeat this procedure.

For this purpose, you can purchase a heat-shrinkable or polyethylene tube of flowers corresponding to the generally accepted core marking, which was mentioned at the beginning of the article, or use tags for this purpose.