How to determine the phase and zero of a multimeter

It is easier to work when the electric supply circuit of the house is grounded correctly, we will show that there is always a way out. We will explain how to understand where the phase is, and how to find out where the zero is. Grab your favorite M890S!Let's see how to determine the phase and zero with a multimeter.

. The simplest methods for finding the phase, zero by an

multimeter. Properly organized house ground loop eliminates problems. First, the isolation of PEN is yellow-green. It is impossible to confuse with the brown( red) phase, blue neutral. Sometimes, the wiring is laid, violating the requirements, colors are confused, absent altogether( aluminum cable).Phase search multimeter carried out by a simple algorithm:

  1. Suppose the apartment has three wires: phase, zero, earth.
  2. We put the multimeter on the alternating voltage range of 750 volts, we begin to test the wiring in pairs.
  3. There will be 230 volts between the phase and any other wire( effective value), the earth-neutral jumper approximates 0.


The access shield has at least five wires, three phases. The further process is determined by the fantasy of local electricians. Good masters hang stickers A, B, C indicating the location of the phases. Grounding is yellow-green, neutral is more often blue.

Adjacent phases voltage 380( 400) volts. High-rise apartments are sometimes supplied with two phases. Electric stoves with power above 10 kW try to divide consumption. Reduced wiring requirements. We advise you to immediately take a marker, mark the insulation with the desired colors. A house devoid of grounding usually receives two wires: a phase, a neutral. The transformer substation drives three phases. How many will be in the apartment, you should find out.

Problems will start when there is no wire marking, the phase comes alone. Between the dangerous wires the voltage will be. .. zero!

  • Two wires carry a phase, neutral one, forgot to ground the ground. Between the supply conductors round zero, when evaluating the neutral wire, we get 230 volts. The situation looks like the phase conductors have become neutral and zero. Made a mess when laying - what can you do? It is required to look for an additional source of support. Suitable screwdriver indicator.
  • Two wires of one phase, the second pair - ground, neutral. They will show zero in pairs, 230 V crosswise. Use the reference guide.

There is no probe screwdriver, with the help of a tester, no matter how you call the wiring, the problem will remain. A reference source, guaranteed grounded, is required. Approaches:

  1. A lightning conductor's ground loop often leads along the outer wall of a building, a strip of steel touches the end of the balcony. Goes vertically down. Grounded, suitable for the chosen target with two reservations: rust a file with a file, perform work when the sky is cloudless( beware of lightning).
  2. The simplest way out would be a bathroom faucet. The pipes are now plastic. But inside there is an excellent electrolyte - water with dissolved hardness salts. Touch the black probe of the crane sleeve tester, take measurements relative to the pivot point. Use the sidewalls of copper, brass, aluminum fittings. There would be water.

    Indicator Screwdriver

  3. On the platform, the steel body of the shield, if not grounded, is planted( short-circuited) on a zero( neutral) wire. Take measurements relative to the selected reference point.
  4. Gas pipe - a taboo for those who want to start grounding, is at zero potential, in contact with the ground. You will find chipped paint, use accessory for the purpose of( cutting the paint yourself is forbidden) phase identification, neutral, grounding.
  5. For the above reasons, batteries made of cast iron, aluminum, have become recognized as a good guideline. The main thing is to ensure close contact. How to check? Call two points of the body. Resistance is units of ohm - the norm. Provided that the heating is on. According to regulations, the pump casing is grounded, the probability of error is low.
  6. It is not recommended to use sewer pipes as a supporting ground source. The conductivity conditions are determined by the amount of. .. drains.

Due to the variety of methods, unreliability is recommended to conduct tests before starting serious work. Measure the potential between the specified landmarks, the outlet phase. Is the distance between the reference point large? We take extension cord. Particularly good is the power filter of a personal computer, equipped with a characteristic illuminated button. Phase on the left, the left pin of the plug( depending on which side to turn) is marked with a marker.

Then we call with an outlet( without power, of course), we make a mark with the right side. We explain, it is possible to do without it, it is better to set aside the jokes with the electrician. It remains to find the phase, using the M890S.We put the range above 380 volts( between the two phases), begin to measure the potential difference between the terminals and the shield. We believe that the further algorithm is clear.

Correctly measure phase consumption.

Measure the phase load. To put the right machines, keep uniform consumption. According to the rules of a three-phase network, each branch is loaded in the same way, avoiding distortions on the supplier’s side. Let us estimate which phases enter the apartment. Easier to look at the access shield. An inexperienced person must stop trying to climb there. Easy to get an electric shock.

The house is old - in sight you will see a large steel plate, which is clearly connected to the hull. The signified is neutral. The house is powered by a three-phase voltage of 380 volts. Each apartment is supplied more often with one phase. Three clips are observed in addition to the grounding terminal. Look where the wires go: automatics, knife switches( according to the bill of apartments).A typical number of site neighbors of three simplifies the analysis task.

Now we know the method of finding the phase with a multimeter, we can safely( with caution, observing safety measures) poke probes. Take the trouble to set the correct range, do not burn the device. Measure or confirm or deny assumptions. Phases two - each load equally. Examine the junction boxes, most of the old houses are under the ceiling( large round holes of the wall).Turning off the supply of the apartment, armed with a tester, understand where and what is going. Use the radical method - cut off one stopper, see where the power went.

The load of the two phases is uneven - correct. It is better to do for machines and traffic jams, which will have a positive effect on reducing the cost of the equipment of the switchboard. On top of this, we say that the rules of work provide for the implementation of such activities in the number of at least two persons. One is sure to insure and is ready to cut off the supply of energy, cut off the current-carrying core or kick away the person suffering from an electric shock from a dangerous area.

Flat two-phase power supply system

How to measure three-phase voltage with an

multimeter In this section, we’ll rather discuss the specifics of three-phase networks. Most multimeters can measure voltages up to 750 volts AC, which is enough to work with serious industrial networks. Each house is supplied from three phases. And the fact that the industry is called neutral, we call the neutral wire.

Enterprise networks are of two types:

  1. The mechanisms with insulated neutral do not use the neutral wire. Inside the load, the phases are equalized, the currents flow through the same wires, of which there are a total of three. If you look for a neutral, there is no line. Three wires of phase, relative to the ground will show a voltage of 230 volts, between them - 380.
  2. A grounded neutral is a neutral wire. It is marked with the letter N on the boxes. It is useful to look at the schematic diagrams of industrial devices shown on the case. It will help to understand the layout.

Having mastered the methods of working with three-phase voltage, everyone can better understand the electrical wiring of a multi-storey building. Where four cores rise from under the shield: three phases and a neutral.

Phases of the car

Electric networks help many objects. A car is considered a relatively simple device. The basis of the supply is a battery of 12 volts( actually - 14.5 V), a generator, the output voltage level of which is regulated according to variations of turns. Voltage after rectification is suitable to feed the battery on-board network. The generator shaft is activated by the battery through a special regulating device.

Three-phase Larionov

The Larion phase circuits rectified by the diode bridge feed the car. Popular today technique. There are six diodes. Phases merge mechanical union after straightening a single highway. Provides maximum power. Sensitive components of the car( on-board computer), additionally rectify the unstable current. To extend the life of the device.

Next, the voltage goes to consumers. Janitors, display system, lighting, ignition. The on-board computer may issue a coded message: it's time to check the phase sensor. The element that uses the Hall effect determines the position of the engine camshaft. Equipped with similar washing machines, assessing the speed of rotation. Auto determines the angular position of the shaft. The sensor emits pulses, evaluating the parameters which the computer will receive the necessary information.

Auto sensors are stuffed. Two terminals are energized, the third generates a signal. To check, let's look at the scheme: the location of the nodes. Then close deal dialing. Simulating the conditions of the formation of pulses, use a permanent magnet.

The question of how to determine the phase and zero with a multimeter on a car disappears. The support is the car body - weight. Understandably, the generator only works when the engine is running. Inside the apartment we are looking for a phase and zero, here the mass is given a priori. Punched insulation can be caused( for example, rectifier bridge diodes).On the car is easier to measure three phases with a multimeter. Actual value indirectly said. About 20 volts( considering the loss of a non-ideal bridge).

Errors of users of the multimeter

Chinese multimeters are configured to work, even if the probes are not set correctly. Break the device by accident. Avoid the method: plug the black wire into the high current measurement connector, the red one into place. Try to measure the alternating voltage of the high-voltage line - repair is provided. Do not use wrong ranges. Renounce trying to measure alternating voltage by applying a constant scale. Phase verification will be the last in the life of a multimeter.

The device is disabled by a large voltage of alternating polarity. Others( for example, incorrect probe polarity) are not so bad.

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