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Commissioning or reconstruction of electrical wiring in a house or apartment is rarely complete without installing or replacing an electric meter. According to the standards, only specially trained people who have permission to work in networks with voltages up to 1000 V can perform work. But you can install all the elements, connect the meter to the load (electrical appliances), without connecting the power supply yourself. After that, you need to call a representative of the energy supply organization to test, seal and start the system.
Connecting the meter: rules and basic requirements
Precisely all the requirements are spelled out in the PUE, and the basic rules are as follows:
- Must be installed with weather protection. Traditionally, they are mounted in special boxes (boxes) made of non-combustible plastic. For outdoor installation, the boxes must be airtight and must provide the ability to control readings (have glass opposite the scoreboard).
- It is fixed at a height of 0,8-1,7 m.
- The meter is connected with copper wires with a cross section corresponding to the maximum current load (available in the technical conditions). Minimum cross section for connecting an apartment electric meter 2,5 mm2 (for a single-phase network, this is a current of 25 A, which is very small today).
- Conductors are used isolated, without twists and branches.
- With a single-phase network, the date of state verification of the meter is no older than 2 years, with a three-phase network – one year.
The installation location of the meter in apartment buildings is regulated by the project. The counter can be installed on the landing or in the apartment – in the shield. If placed in an apartment, then usually not far from the door.
In a private house, there are also several options. If the pole is in the yard, you can place the counter on the pole, but indoors is better. If, according to the requirements of the energy supply organization, it must be located on the street, they put it on the front side of the house in a sealed box. Automatic machines going to groups of consumers (various devices) are mounted in another box in the room. Also one of the requirements for installing electrical wiring in a private house: the wires must be visually visible.
In order to be able to carry out work on the electric meter, an input knife switch or automatic machine is installed in front of it. It is also sealed, and there is no possibility to put a seal on the device itself, as on a counter. It is necessary to provide for the possibility of a separate sealing of this device – buy a small box and mount it inside the apartment shield or put it separately on the landing. When connecting a meter in a private house, the options are the same: in one box with a meter on the street (the whole box is sealed), in a separate box nearby.
How to conduct electricity from the pole to the house, read here.
Two-tariff meters and the calculation of their efficiency are described here.
Wiring diagram for a single-phase electric meter
Meters for a 220 V network can be mechanical and electronic. They are also divided into one-tariff and two-tariff. Let’s say right away that the connection of a meter of any type, including a two-tariff one, is made according to one scheme. The whole difference is in the “stuffing”, which is not available to the consumer.
If you get to the terminal plate of any single-phase meter, we will see four contacts. The connection diagram is indicated on the reverse side of the terminal cover, and in the graphic image everything looks like in the photo below.
If you decipher the scheme, you get the following connection order:
- Phase wires are connected to terminals 1 and 2. The phase of the input cable comes to 1 terminal, the phase goes to consumers from the second. During installation, the load phase is connected first, after it is fixed, the input phase is connected.
- 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 connecting contacts is similar – first 4, then 3.
Pin lugs
The meter is connected with 1,7-2 cm stripped wires. The specific figure is indicated in the accompanying document. If the wire is stranded, lugs are installed at its ends, which are selected according to the thickness and rated current. They are pressed with tongs (can be clamped with pliers).
When connecting, the bare conductor is inserted all the way into the socket, which is located under the contact pad. In this case, it is necessary to ensure that no insulation gets under the clamp, and also that the cleaned wire does not stick out of the housing. That is, the length of the stripped conductor must be maintained exactly.
The wire is fixed in old models with one screw, in new ones with two. If there are two fixing screws, the far one is screwed first. Gently tug on the wire to make sure it is secure, then tighten the second screw. After 10-15 minutes, the contact is tightened: copper is a soft metal and is slightly crushed.
Learn how to wire your own home here. About the features of electrical wiring in a wooden house is written here.
This is about connecting wires to a single-phase meter. Now about the connection diagram. As already mentioned, an input machine is placed in front of the electric meter. Its rating is equal to the maximum load current, it works when it is exceeded, excluding equipment damage. After they put an RCD, which works when there is a breakdown of the insulation or if someone touches the current-carrying wires. The scheme is shown in the photo below.
The scheme is easy to understand: from the input, zero and phase are fed to the input of the circuit breaker. From its output, they enter the meter, and, from the corresponding output terminals (2 and 4), go to the RCD, from the output of which the phase is supplied to the load circuit breakers, and zero (neutral) goes to the neutral bus.
Please note that the input automaton and the input RCD are two-contact (two wires come in) so that both circuits open – phase and zero (neutral). If you look at the diagram, you will see that the load breakers are single-pole (only one wire enters them), and the neutral is supplied directly from the bus.
Watch the connection of the counter in video format. The model is mechanical, but the process of connecting the wires is no different.
The self-assembly of the electrical panel is described in this article.
How to connect a three-phase meter
There are three phases in the 380 V network, and electricity meters of this type differ only in a large number of contacts. The inputs and outputs of each phase and neutral are arranged in pairs (see diagram). Phase A enters the first contact, its output is on the second, phase B – input on the 3rd, output on the 4th, etc.
The rules and procedure are the same, only more wires. First, we clean, align, insert into the connector and tighten.
The connection diagram of a 3-phase meter with a consumption current of up to 100 A is almost the same: an input automatic meter-RCD. The only difference is in the distribution of phases to consumers: there are single- and three-phase branches.