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August 12, 2017 18:06

How to determine the phase and neutral

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When mounting sockets and light switches, connecting household appliances is necessary to determine the assignment of the posting.How to determine the phase and "zero", as well as a grounding conductor?This simple task for professional electricians sometimes bewilders those who are not familiar with the electrical network device regulations.Let's try to sort out this issue.

device household electrical networks

Domestic electrical network at the entrance to the distribution panel are line voltage AC 380 Vtrehfaznogo.Wiring in apartments, with rare exceptions, has a voltage of 220 V, since it is connected to one phase and the neutral conductor.In addition, properly mounted household wiring must always be grounded.In the homes of old buildings grounding conductor may not be.Thus, when mounting electrical wiring and needs to know what each of the two or three wires.

should also know the rules of the connection of various devices.When installing the usual socket connection of the phase and neutral conductors to the terminals in any order, and the ground wire, if present, are connected to copper or brass bus.The switch is connected to the live wire, so that when it is turned off in the fixture holder has not been stress - this will ensure safety when changing lamps.Complex household appliances in a metal case must be connected in accordance with the mandatory marking of wires, otherwise the safety of their use is not guaranteed.

equipment and instruments

Before electrical work and determine the phase and zero in the wiring, it is necessary to prepare the necessary instruments and tools:

  • dial or digital multimeter;
  • indicator screwdriver and tester;
  • Marker;
  • pliers;
  • Knife for stripping insulation.

You also need to figure out where the protective equipment: circuit breakers or fuses, RCD.They are usually installed in the control panel on site, or at the entrance to the apartment.All operations on the connection of electrical equipment and cleaning of wires should be carried out when disconnected machines!

Rules of work with tester and multimeter

phase check using the indicator screwdriver conducted as follows: a screwdriver pressed between thumb and middle finger of the hand without touching the bare part of the sting.The index finger is put on metallicheskiypyatachok from the end of the handle.Sting graze bare wire ends, at the touch of a phase conductor LED lights.

We determine the phase and zero with the indicator screwdriver

determines the phase and zero with the help of a screwdriver indicator

multimeter measures the voltage between the conductors.To do this, the device is set to limit the AC measurement marked with «~ V», or «ACV» and a value greater than 250 (usually in digital devices choose between 600, 750 or 1000).Probes simultaneously touch the two conductors and determine the tension between them.The household power it should be 220V ± 10%.

sometimes to determine the grounding conductor is necessary to measure the resistance.To do this, put a limit on the multimeter measurement «Ω» or with the call icon.

Instructions on using a multimeter

instructions on using a multimeter

Attention!In resistance measurement mode, touch to the phase conductor and the grounding circuit will cause a short circuit!This is possible electrocution and burns!
visual method for determining

If the wiring is done according to the rules, to determine the phase, zero and earth conductor can be in color isolation.Grounding has two-tone yellow-green color, the isolation of the neutral conductor is blue, or blue, and the phase wire can be white, black or brown.Be sure to connect, you can use visual inspection, at the same time check that the color of the insulation is not only plate, but also in the distribution boxes.

sequence of visual inspection

  1. Open the flap and check the circuit breakers.Depending on their design load amount may be different.Through the machines may only be connected to phase or phase and neutral conductor.The grounding conductor is connected to the bus is always right.Check the color coding of the wires.
  2. If the panel color of the cable insulation, leaving the apartment, abuse, unpack all the boxes and inspect the stranding.They colored insulation zero and the ground wire and should not be confused.
  3. By phase distribution boxes are connected to switches.Installation is often performed two-core wire having other colors isolation, for example, white and blue and white.It should not confuse you.
  4. When installation is complete with matching color isolation, is sufficient to check the phase wire with the help of a screwdriver indicator.
Definition phase and zero in the two-wire network

If your wiring is no grounding wire, you need to find only the phase wire.Make it easier just using a screwdriver indicator.

Indicator screwdriver will help us to determine the phase and neutral

Indicator screwdriver will help determine the phase and zero

  1. Turn off the circuit breaker and strip the insulation of the wires at a distance of 1-1.5 cm with a knife.Dissolve them in the distance, which excludes accidental contact wires.
  2. Turn on the circuit breaker.Indicator screwdriver alternately touch the stripped ends of the wires.Glowing LED will indicate the phase wire.Note
  3. his marker or colored tape, turn off the circuit breaker and make the necessary connections.
  4. When connected lighting is also necessary to ensure that the switch is connected to the phase conductor, otherwise, when changing light bulbs will not be enough to turn off the switch, it is necessary each time completely de-energize the apartment turning off the machine.

Definition phase, zero and earth wire

If the network is three-wire, but the wire is made of the same color, or you are not sure it is properly connected, it is necessary to determine the purpose of the conductors prior to installation of each network element.

The definition phase and zero ground wire

Definition phase and zero ground wire

  1. Determine the manner described above using a live wire indicator screwdriver and check its marker.
  2. To determine the zero and the ground wire will need a multimeter.As you know, stress can appear due to phase imbalance in the neutral wire.Its value is usually not greater than 30V.Set the multimeter to measure AC voltage mode.One probe touch the phase conductor, the second turn to the two other wires.Where the voltage value is less than, the second wire will be the neutral conductor.
  3. If the voltage value is the same, it is necessary to measure the resistance of the ground wire.To do this, it has a certain phase wire should be isolated to avoid accidental contact with it.Multimeter put in resistance measurement mode.Find deliberately grounded element, such as a pipe or the battery.Stripping paint if necessary, and touch one probe multimeter to the metal, while others turn to the conductors, the purpose of which is unclear.Resistance grounding wire with respect to the grounded elements should not exceed 4 ohms, the resistance of the neutral conductor will be larger.
  4. resistance measurement can also be misleading, if the neutral is grounded in the shield.In this case, you need to find a grounding conductor connected to the bus inside the panel, and turn it off.After this, you need to take a cartridge with a lamp and connected the wires to clean the ends and connect one lamp wire to the phase wire, and the second - in turn to the other two.The lamp lights up at the touch of a neutral conductor.

If all these measures do not lead to the desired result, it is better to turn to a professional electrician, who with the help of special devices produce vyzvonku all circuits.Do not forget that we are talking primarily about safety.

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