How to connect a meter yourself: single-phase and three-phase meters

Commissioning or reconstruction of the electrical wiring in a house or apartment rarely takes place without installing or replacing an electric meter. According to regulations, the work can only be performed by specially trained people authorized to work in networks with voltage up to 1000 V. But you can install all the elements, connect the meter to the load (electrical appliances), without connecting the power supply yourself. After that it is necessary to call a representative of the energy supplying organization for testing, sealing and start-up of the system.

Connecting the meter: rules and basic requirements

Exactly all the requirements are spelled out in the PUE, and the basic rules are as follows:

• It must be installed with protection from the effects of weather conditions. Traditionally mounted in special boxes (boxes) made of non-combustible plastic. For outdoor installation, the boxes must be airtight and must provide the possibility of controlling the readings (have a glass opposite the scoreboard).
• It is fixed at a height of 0.8-1.7 meters.
• Connection of the meter is made by copper wires with the cross-section corresponding to the maximum current load (it is in the technical conditions). The minimum cross-section for connecting the apartment electricity meter is 2.5 mm2⁽ for a single-phase network it is a current of 25 A, which is very small today).
• Conductors are used insulated, without twists and branches.
• For single-phase network the date of state verification of the meter – not older than 2 years, for three-phase – one year.

The place of meter installation in apartment buildings is regulated by the project. The meter can be installed on the staircase landing or in the apartment – in the switchboard. If it is installed in the apartment, it is usually not far from the door.

In a private house, too, there are several options. If the pole is in the yard, you can place the meter on the pole, but better – in the room. If, according to the requirements of the energy supplying organization, it must be on the street, put it on the front side of the house in a sealed box. The automatons going to consumer groups (various devices) are mounted in another box in the room. Also one of the requirements when installing electrical wiring in a private house: the wires must be viewed visually.

In order to be able to carry out work on the electric meter, an input switch or automatic machine is installed in front of it. It is also sealed, and it is not possible to put a seal on the device itself, as on the meter. It is necessary to provide the possibility of a separate sealing of this device – buy a small box and mount it inside the apartment panel or put it separately on the staircase landing. When connecting the meter in a private house, the options are the same: in the same box with the meter on the street (the whole box is sealed), in a separate box next to it.

How to conduct electricity from the pole to the house read here.

Two-tariff meters and calculation of their efficiency are described here.

Wiring diagram of a single-phase electric meter

Meters for the 220 V network can be mechanical and electronic. They are also divided into single-tariff and dual-tariff. Let’s say at once that the connection of any type of meter, including two-tariff, is made according to the same scheme. The difference is in the “stuffing”, which is not available to the consumer.

If you get to the terminal plate of any single-phase meter, you will see four contacts. The connection scheme is indicated on the reverse side of the terminal cover, and in the graphical representation everything looks like the photo below.

If you decipher the scheme, the following connection order is obtained:

1. To 1 and 2 terminals are connected to the phase wires. On the 1 terminal comes the phase of the input cable, from the second comes the phase to the consumers. When installing the first one, the load phase is connected, after it is fixed – the input phase.
2. To terminals 3 and 4 the neutral wire (neutral) is connected according to the same principle. To the 3rd contact neutral from the input, to the fourth – from consumers (automatic machines). The order of connection of contacts is similar – first 4, then 3.

   

The meter is connected with wires stripped by 1.7-2 cm. The specific figure is specified in the accompanying document. If the wire is stranded, lugs are installed on its ends, which are selected by thickness and rated current. They are pressed with pliers (can be clamped with pliers).

When connecting, the bare conductor is inserted as far as it will go into the socket located under the contact pad. It is necessary to make sure that the insulation does not get under the clamp and that the stripped wire does not stick out of the housing. That is, the length of the stripped conductor must be maintained precisely.

The wire is fixed with one screw in the old models and two screws in the new models. If there are two fixing screws, the farthest one is screwed in first. Slightly twitching the wire, make sure that it is fixed, then tighten the second screw. After 10-15 minutes, the contact is tightened: copper is a soft metal and a little crumpled.

How to make your own wiring in the house read here. About the features of wiring in a wooden house is written here.

This is what concerns the connection of wires to a single-phase meter. Now about the connection scheme. As already mentioned, before the electric meter is put an input automatic circuit breaker. Its nominal value is equal to the maximum load current, triggers when it is exceeded, excluding damage to the equipment. After putting the RCD, which is triggered by insulation breakdown or if someone touched the current-carrying wires. The scheme is presented in the photo below.

The scheme for understanding is simple: from the input zero and phase come to the input of the protective automatic machine. From its output they fall on the meter, and, from the corresponding output terminals (2 and 4), go to the RCD, from the output of which the phase is fed to the load circuit breakers, and zero (neutral) goes to the zero bus.

Note that the input circuit breaker and input RCD two-pin (two wires go in) to open both circuits – phase and zero (neutral). If you look at the diagram, you will see that the load circuit breakers are single-pole (only one wire goes to them), and the neutral is fed directly from the busbar.

See the meter connection in the video format. The model is mechanical, but the process of connecting the wires is no different.

About the independent assembly of the electric panel is described in this article.

How to connect a three-phase meter

In the 380 V network there are three phases, and electric meters of this type differ only in the large number of contacts. The inputs and outputs of each phase and neutral are located in pairs (see the diagram). Phase A enters on the first contact, its output on the second, phase B – input on the 3rd, output on the 4th, etc.

The rules and order of operation are the same, only a greater number of wires. First we strip, align, insert into the contact connector and tighten.

The scheme for connecting a 3-phase meter with a current consumption of up to 100 A is almost the same: input circuit breaker-counter RCD. The only difference is the phase distribution to consumers: there are one- and three-phase branches.