Why do you need non-disconnect lines in the shield and how to make them

A modern electrical panel in an apartment or a private house is not the usual two traffic jams on the meter, but a rather complicated input-distribution device. In which each consumer group is protected by its circuit breaker and RCD. One of the not quite ordinary groups are non-disconnect lines. What is it and how to connect them to the dashboard, we will describe further.


Non-disconnected lines, groups or chains is a conditional concept. It is understood as electrical appliances that are connected separately with respect to other electrical appliances. Non-disconnectable include power circuits:

  • security systems and alarms;
  • refrigerators;
  • circulation heating systems;
  • septic tanks and stuff.

Let's see what the non-disconnect lines in the shield are for! Let's say you are going to leave and in this connection you want to turn off the electricity in the house in order to protect yourself from emergency situations. However, if there are products left in the refrigerator, they will melt and disappear, and in winter the water in the heating system will freeze and pipes will be damaged, which is especially important in a private house or in the country.

Those who have installed video surveillance or alarm will have a problem - the system will be de-energized. Of course, security systems are connected through an uninterruptible power supply, but usually the capacity of its battery is selected for a period from several hours to a day of battery life.

In this regard, there is a need to separate the non-disconnected lines from the rest of the power network of the house.

Shield layout

Standard option

To begin, consider the electrical circuit of a typical electrical panel without non-disconnectable circuits, it looks like this:

Switchboard assembly diagram

  • AB1 is an introductory machine, usually installed in a metering panel in a private house, and in an apartment - in a floor board.
  • AB2 is an introductory machine or circuit breaker in an apartment switchboard.
  • AB3-7 are group automatic machines for light, sockets, electric stoves and other consumers.

Here, if you need to disconnect the apartment, disconnect all circuits without exception. Let's look at what to include in a group of non-disconnected lines in more detail.

To connect additional circuits that will not be disconnected with the main power supply circuit, you need to do branch before the opening switch in the electrical panel with group AB. That is, up to AB2, if we consider the previous scheme.

Non-disconnectable groups in the shield

Then on this scheme everything will be similar to the previous one, only AB8-AB10 - these will be circuit breakers that are not switched off by the opening breaker or automatic machine. From them the alarm system, refrigerators and other will be powered.

Circuit with RCD

We supplement the circuit with differential protection, so the circuit with non-disconnectable lines and RCDs will look like:

Scheme with fire and group RCD

You can learn more about what an RCD is from our article: https://my.electricianexp.com/en/chto-takoe-uzo-i-kak-ono-rabotaet.html. Naturally, the scheme above can be modernized at your discretion, for example, by adding a fire-protective RCD, adding an RCD for each group of consumers, or by replacing a bunch of AB + RCDs with difavtomaty and save space in the electrical panel.

For example, in this diagram, a fire protection RCD with a large tripping current (for example 300 mA) and two group RCDs of 30-50 mA are at the input.

Scheme with an introductory RCD

Circuit with voltage relay

If you have an unstable power grid - it will protect voltage relay.

Circuit with voltage relay and RCD

However, sometimes disputes arise regarding the connection of non-disconnect circuits in such a case. Sometimes they are connected to the voltage relay, but then you need to remember that in case of accidents on the line (phase imbalance) This equipment will be in danger.

Circuit with contactor or starter

To disconnect the main consumers by pressing 1 key, you need to connect them through actuator or through contactorminus non-disconnect lines. To do this, you can use a simple light switch or toggle switch.

Switchboard layout with contactor

In order to gain control of the main part of the electrical network of your housing via the Internet via Wi-Fi, you need to add a relay to the previous Wi-Fi circuit, replacing it with a switch. To do this, you can use the Sonoff relay, which was popular at the time of writing:

Wiring diagram with wifi relay


Non-disconnected lines are a fairly important concept in electrics. Their purpose is that these circuits can improve the reliability of the operation of important electrical systems in your apartment or home. Indeed, if the main machine is knocked out, they will continue to work. The above schemes are easy to upgrade or scale to your needs. Their organization in three-phase circuits is no different from the above example, with the exception of phase distribution of consumers, the number of poles of the contactor and other switching devices.

We list the advantages and disadvantages of this approach to the design of the circuit board.


  1. Uninterrupted operation of security systems, refrigerators, pumping equipment for heating, water supply and sanitation.
  2. Greater convenience during repair work both on the main and equipment that does not turn off. That is, there is no need to disconnect consumers in whose chain repairs will not be carried out.

There is only one significant drawback - there may be errors of electricians who first see your electrical panel. After turning off the introductory machine, voltage will remain on some consumers. Therefore, you need to correctly assemble the shield and sign the machines.

Now you know how to make non-disconnect lines in the shield and why they are needed. We hope that the provided schemes helped you understand the issue and choose the most suitable option for assembling the shield for your own conditions!

Surely you do not know:

(6 votes)


  • Anton Dilev

    Allow me. But is it possible that in the scheme where the non-disconnected lines are shown for the first time (the second scheme in the article) does the AV2 automaton not disconnect the zero line? Does this not only make these lines disconnectable, but also dangerous?

    To answer

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