How to connect the oven and hob, diagrams

There are usually two scenarios for connecting the oven and hob:

• household appliances are already in the kitchen, and you know their characteristics;
• the purchase is only planned, their technical data is not known.

In both cases, the connection can be made in two ways:

• through a socket into which the plug of the connecting cord is connected;
• through a permanent connection, which is preferable in situations where the equipment is permanently connected to the network.

In the article, we will consider all the above scenarios and methods, tell you how to calculate wiring and other important connection nuances.

It will be about connecting a separate hob and oven to one cable.

The origins of the problem

Often in the kitchen of an apartment or a private house, only one electrical outlet is provided at the equipment connection point. This is how the living quarters were designed, especially for old houses.

At the same time, we face the task of ensuring the simultaneous connection of two independent loads, each of which has its own electrical input.

This situation becomes critical when the electrical equipment:

• has a high power, which does not allow solving the task through a multi-socket extension cord or tee;
• due to its purpose, it was not originally designed for frequent connections and disconnections.

An additional complicating factor is that the electrical appliances located at this load point, in our case, the oven and the hob, must function simultaneously, and it is not possible to solve the problem by alternatively connecting one of the devices to another point.

The described situation occurs when it is necessary to ensure the operability of an electric hob and an electrically heated oven, which are not always made in the form of a monoblock device.

Designers and builders, by default, used to consider these two devices in terms of power consumption as a single unit and, accordingly, laid only one cable at the connection point specified in the project.

Now the situation has changed and all possible options are taken into account.

Rationale for separate connection

The PUE states that a dedicated cable with a separate circuit breaker should be used to power household loads whose power exceeds 3,5 kW. This means that a radial scheme must be implemented for the power supply.

In our case, the hob often has a power that is higher than one kilowatt. Despite the fact that the oven is a less powerful device, there are models that consume one and a half or more kilowatts.

Therefore, these two devices can be considered as a whole not only from the point of view of their functional purpose: cooking, but also from the point of view of the load.

Preliminary remarks

When connecting the oven and hob, a number of requirements must be met regarding wiring and the circuit breaker:

They include:

• the wire is known to be good;
• withstands continuous maximum load;
• contains the required number of working cores, zero and ground;
• complies with all safety standards.

When choosing a machine, it makes sense to be guided by the values ​​​​of 25 A for a total load power of up to 5 kW and 32 A for a higher power (see table below).

Table. Limits for 220-volt single-phase wiring for cables with a conductor cross section of 4 mm².

Selection of the cross section of the cable cores

In continuation of the above, the oven and hob must be connected through a cable whose cross section will ensure their simultaneous operation at maximum power. Otherwise, a separate line is laid for the second device with a cable cross section of at least 2.5 mm².

But before making calculations, it is important to get the initial data:

• cable cross-section material (aluminum, copper);
• maximum power consumption of devices;
• according to what scheme the wires are laid (open, in a box or closed).

If there is power data in the accompanying documentation of the connected equipment, you can even not perform arithmetic operations.

To do this, just refer to the table above, which is an excerpt from the relevant provisions of the regulatory part of the PUE in the 7th edition and contains information on the maximum load capacity of a cable with a core cross section of 4 mm².

From the data presented in the table, it is immediately clear that

• in most cases, modern electric stoves and ovens do not require connection to a 3-phase network;
• to implement the idea, cables with a 4-mm cross-section of cores are enough;
• in the absence of strict budget restrictions, it is advisable to use a cable with copper conductors, which gives a 30% gain in load;
• laying the cable in the box does not reduce its load capacity.

The latter is explained by the fact that the box does not restrict air circulation, i.e. due to the large gaps does not reduce the efficiency of air cooling even at full load.

Selection of household appliances based on the possibility of existing wiring

Let’s go a little deeper into the topic so that everything is clear.

If you are only planning to buy an oven and a hob, then it is important to understand whether the existing wiring can withstand the total power of both devices, and not a short-term, but a continuous load.

To do this, you need to find out what cross section the wires have and, based on this, make calculations or use ready-made tables.

Use a caliper to measure the cross section of the wire. A regular ruler will not work, as measurements will have a large error.

Do the following:

• De-energize the cable.
• Strip the insulation of one core at least 1 cm.
• Take measurements with a caliper.

Next, use the formula from the school course: S=π×d²÷4.

Where:

• S is the desired cross-sectional area.
• D is the measured diameter.
• P = 3.14.

For example, measurements showed a core diameter of 2.4 mm. We carry out the calculation: 3.14×2.42÷4=4.52mm². The recommended figure is from 4 to 6 square millimeters.

In new houses, built after 2001, the conductors are usually copper, in old ones they are mostly aluminum.

Further, according to the table below, you can find out how much power this cable can withstand.

Knowing the power that the wiring laid in the wall can withstand, you can go to the store and select household appliances based on its characteristics and taking into account that it will be connected to one point. All data can be found in the technical data sheet.

Otherwise, if household appliances have already been purchased, and the cable section is not enough, you will have to draw another line from the shield.

Often in cables, wires with a cross section of 2.5 mm are used.². Therefore, it is advisable to consider them as an example for a 220V network.

As can be seen from the table above, such a wire will withstand:

1. Closed wiring – current 21A, power 4.6 kW for a copper conductor and current 16A, power 3.5 kW for an aluminum conductor.
2. Open wiring – current 30A, 6.6 kW for copper and current 25A, power 5.2 kW for aluminum core.

Therefore, it is advisable to use wires with copper conductors.

But in most cases, the cross section is 2.5mm² will be missed, so it is advisable to consider wires with a cross section of 4 mm². As they say – “With a margin.”

Here are the relevant numbers:

1. Closed wiring – current 27A, power 5.9 kW for a copper conductor and current 21A, power 4.6 kW for an aluminum conductor.
2. Open wiring – current 41A, 9 kW for copper and current 32A, power 7 kW for aluminum core.

It is wires with a cross section of 4 mm² and more is recommended to use for simultaneous connection of two household devices.

Focusing on amperes, we also select a circuit breaker, for example, if the wire can withstand a current of 27A, then it is advisable to choose an AZ for 32A (why overpay), this is quite enough.

About the demand factor

The demand coefficient is calculated by the formula Кс=Рр/Рн, where:

1. Рр – design power.
2. Рн – the total power of electrical consumers, in our case, the oven and the hob.

In simple terms, if the demand coefficient is 1, this means that it is possible to simultaneously use all electrical appliances of the same network at maximum power. But in practice this rarely happens.

For example, 0.7 indicates that electrical appliances are used individually or simultaneously, but not at maximum loads, provided that they are connected to one point.

Below is a table for calculating the power consumption of an apartment, taking into account the demand factor.

What do we want to say? And what if with a wire with a cross section of 4mm² and its load capacity of 5.9 kW, you can purchase electrical appliances that consume more power in total.

For example, you liked certain models of oven and hob, which consume a total of 8 kW at maximum loads. But you do not plan to use these electrical appliances in this mode.

We multiply 8 kW by a demand factor of 0.7 (you can take less, but this figure is the most optimal), we get 5.6 kW, which suits you perfectly.

Connection options

You can connect electrical appliances to the network in detachable and one-piece ways.

Detachable connection is based on the use of a plug and socket, which are pre-mounted on the cable: connected equipment and wiring, respectively. It is convenient and practical.

Permanent connections are made through the terminal block. The advantages of this connection method are a strong and reliable connection of contact pairs, lower cost.

Connection via socket

In practice, the following main versions of sockets are used, which are schematically shown in the figure below:

• assembly of two single sockets with a separate cable for each of them;
• assembly of two single sockets with a common cable;
• monoblock socket with two seats for plugs.

Options for the end section of the wiring for connecting the hob and cabinet, from top to bottom:

• with an individual cable and a machine for each outlet;
• with the installation of a monoblock double socket and a common machine;
• using a daisy chain connection of two sockets and a common machine.

Given the high power consumption of electricity, monoblock sockets with three or more seats are not used in this connection method.

The type of socket used is significantly limited if the panel and/or oven cable is reinforced with a plug. It is impossible to change it to another, since in this case, at least, the factory warranty terminates.

When connecting, it is advisable to use socket modules with different form factors, which are available, including in a double monoblock version.

This simple technique provides the simplest, but at the same time effective connection scheme.

The connection of the hob socket and the plug to the wire is shown below.

Connection via terminal block

Such a connection is carried out in two cases:

• if the connecting cable of the hob or oven does not have a plug;
• if a terminal block is installed as a mains connection element on the device itself.

Figure 4 shows both of these cases in a schematic form.

In the latter case, for connection, connect two terminal blocks with a cable: the device itself and the linear one, and the cable itself is not included in the device delivery set and is purchased separately.

This option is time-consuming to implement, but does not limit the distance between the cabinet / hob and the power cable outlet point, and also allows you to very accurately select the length of the connection cable and avoid loops.

Most often, the functions of a linear terminal block are performed by the so-called barrier block.

This type of terminal block got its name due to the presence of a ledge-barrier that separates the fastening components of the input and output sides of the device.

The block can be installed openly on the wall or mounted inside the cutting box, for which it has the appropriate mounting holes for screws or screws.

Features connecting the panel and cabinet to the barrier block

There are two things to keep in mind when connecting.

The first of them is that the connection of the panel and the cabinet to the linear terminal block, regardless of the version of the connection block of the device itself, is always carried out according to the star scheme, which is shown in a schematic form on the left side of the figure.

The use of the loop diagram on the right side of the figure is not recommended due to the fact that the fixing elements of the hob terminal block are not initially designed to connect two wires to it.

The second feature is that, given the high currents flowing through the socket, it is necessary to provide a low contact resistance in the area where the panel/oven cables connect to the block contact.

To achieve this effect, run:

• reinforcement of individual cable wires with lugs (an example of such a component is shown in the figure below);
• the use of a special crimping tool for their installation.

The correctness of the connection is additionally checked by the color of the insulation of individual cable cores, their purpose is additionally controlled by the accompanying documentation of the device.

Scheme of connection to the machine.

Connecting the Gorenje electric hob

Before starting work, be sure to study the technical characteristics of the selected model with a connection diagram.

Make sure there are jumpers.

Install jumpers between 1 – 2, 4 – 5 pins.

We unscrew the cable clamp, pry it with a screwdriver and take it out.

We connect the wires according to the scheme.

We fix the cable with a clamp.

Next, we pump up the hob in the ways described above.

Conclusion

As you can see, the oven and hob as separate devices, if such a need arises, can be purchased separately with subsequent connection to one power cable.

The implementation of such a procedure fully complies with the requirements of the provisions of the relevant sections of the current version of the PUE.

The connection process itself is implemented according to the usual scheme of working with household electrical appliances, is carried out taking into account simple additional restrictions, does not require the use of special tools and, subject to certain accuracy, can be carried out even with the level of knowledge of a high school physics course.