If you do not yet have a standby power plant and are only in the planning and selection phase, our articles How to Choose a Standby Generator and How to Use a Generator: Refueling, Starting, Breaking in and Maintaining may be useful sources of information on these questions.

Method number 1: connecting the generator to the house through an outlet

The easiest way to connect a generator to your home is to "plug" it directly into an outlet. The principle of this method is very simple: if a current source is connected to the outlet, then the voltage will be in neighboring sections of the electrical circuit. To connect the generator to the home network in this way, you need to buy a cord with two plugs or make it yourself from a cable and two plugs from extension cords or worn-out household appliances. One plug is inserted into the generator socket, the second - into one of the sockets in the house.

Attention: in some countries this method of connecting the generator is prohibited. Check local laws or consult a certified electrician.

It should be borne in mind that connecting the generator directly to the outlet is only allowed if the house is completely disconnected from the general power supply system (that is, you must first “cut down” the machine in the input shield or unscrew the plugs). Otherwise, part of the electrics produced by your equipment will go “outside”. And when the power supply is restored, the winding of the generator connected to the outlet can easily burn out from oncoming currents (and not in a figurative, but in a direct sense - the risk of fire is extremely high).

The scheme of connecting the generator to the house through a socket.

This connection method is only suitable for small and medium power generators. It is absolutely impossible to connect powerful power plants directly to the outlet due to the fact that some elements of the household electrical network may not withstand heavy loads. For example, a standard power cable with copper conductors with a cross section of 2.5 mm2, which is used for installing an in-house electrical network with a voltage of 230 V, can withstand a load of no more than 4.6 kW (and an aluminium cable of the same cross section - no more than 3.5 kW). The load on a 16A socket should not exceed 3.5 kW, and on a 10A socket - 2.2 kW. Exceeding the specified values will cause the wires and connectors to overheat and melt - a fire may occur.

Moreover, it should be noted that connecting the generator directly to the outlet will not always work as intended if the electrical network in the house is made according to modern rules using RCDs and separate machines for each consumer group. It is likely that only a group of outlets in the network circuit to which the generator set is connected will have voltage, and the remaining consumers will be “cut off” by automation (however, it all depends on the type, design and characteristics of the protective devices and circuit breakers mounted in the switchboard your house).

Given all of the above, the method of connecting the generator directly to a household outlet should be considered solely as an "emergency" option. It is highly discouraged to constantly use this scheme, and it is absolutely impossible to leave such a "collective farm" unattended for reasons of fire safety.

To connect the generator, you can use a socket pre-installed on the outer wall of a private house or garage.

Method number 2: connecting the generator to the house through a breaker

If the power goes out more than once a year, but more often, then it makes sense to “get confused” and slightly improve the home electrical network in order to provide an easy, reliable and safe way to connect the generator to the house. Modernization involves two steps: installing a three-position knife switch and laying an additional cable.

A three-position switch is a device for switching from the main network to the backup network or vice versa. Depending on the design, such devices are sometimes called toggle or reversing switches. They can also appear in online stores and catalogs of electrical engineering under the complex name "I-0-II transfer switch". It is advisable to choose a switch that is mounted on a DIN rail in an electrical panel. It is built into the power supply system after the electricity meter(so that the meter does not take into account the electricity produced by your generator). It is advisable to install an automatic switch between the generator and the knife switch (normal or differential with built-in overcurrent protection) - this will be safer and more reliable.

Wires (“phase” and “zero”) from the power supply network are connected to one pair of the upper terminals of the switch, and exactly the same pair of wires from the generator is connected to the second. The cable going to the consumers is connected to the lower terminals. By switching the breaker, the user can choose which of the branches will receive current - from the network or from the generator. The wires for connecting the backup power source are led outside the house (into the garage, shed or on the outer wall of the building) - to where the generator set will operate.

Scheme of connecting the generator to the house through the switch.

This method of connecting the generator to the house is relatively simple and inexpensive, despite the inclusion of an additional device in the power supply circuit. Therefore, it is he who is most often chosen to provide backup power supply.

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Method number 3: connecting the generator to the house through the ATS unit (ATS)

The two methods described above have a common drawback - each time the power goes out, you must manually insert the plug into the outlet or switch the breaker, and then perform the reverse procedure when the mains voltage appears. This shortcoming is deprived of the method of connecting the generator to the house through the automatic transfer unit.

The ATS unit is a special automation kit that is built into the power supply system in front of the switchboard or instead of it. The function of the automatic transfer unit is, as the name implies, to automatically switch between the main and backup sources of electricity. The ATS unit independently determines the presence or absence of voltage in the main network. If the electricity is lost, the automation instantly reacts and sends a signal to the generator to start via the control cable. The power supply has been restored - the automation shuts off the engine and turns off the backup source of electricity.

Scheme of connecting the generator to the house through the ATS unit (ATS).

On sale there are generator sets, in which the ATS unit is immediately integrated into the design (mainly stationary power plants) or included in the delivery set (as a rule, we are talking about mobile units). You can also buy a generator with a connector for the ATS unit, which is “out of the box” ready for integration into an automated system (but automation must be purchased separately). All such generators have electric starters and batteries, thanks to which the equipment can be started without human intervention.

The method of connecting the generator to the house using the automation unit is the most difficult and expensive to implement. But such a solution is beneficial and fully justified if electricity is lost frequently.

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230 V do not forgive mistakes

All methods of connecting the generator to the home network, described above, are by no means a guide to action. This article is for informational purposes only. It describes the general principles and gives an idea of what you need to buy to connect the generator to the house, and what changes you need to make to the household electrical network. But only specialists who have the appropriate knowledge and approvals should draw up a connection project and carry out work on the installation of a knife switch or ATS unit.

Attention : when connecting a generator to a house, do not ignore common sense and safety regulations. Incorrect connection of the backup power may result in network overload, short circuit or fire.