What wire is needed to connect the hob: cross-section, type and installation diagram

Connecting a hob to an electrical network is a task that requires not only knowledge in the field of electrical engineering, but also strict adherence to safety standards. Errors at this stage can lead to overheating of the wiring, short circuit or even fire. This topic is especially relevant for motorhome and camper owners, where cooktops are often integrated into tight spaces with unique power requirements.

Many motorists who equip the living compartments of their vans or trailers are faced with a dilemma: which cable to choose for powerful equipment, if the standard on-board network 12V or 24V doesn't fit? In this article we will look at wire selection criteria for hobs of different power, nuances of connecting to networks 220V and 380V, as well as typical mistakes that are made when installing in an RV or garage.

Let us note right away: the rules for connecting hobs in stationary kitchens and mobile residential modules (for example, in campers or caravan trailers) have key differences. If in an apartment you can rely on the existing wiring (if it complies with the standards), then in a camper you will have to lay a separate line taking into account vibrations, limited space and the specifics of the power source (inverter or generator).

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1. The power of the hob and its influence on the choice of wire

The first step is definition rated power your hob. This parameter is indicated in the technical data sheet of the device and is measured in kilowatts (kW). Directly depends on power cable section, which must withstand the load without overheating.

Most modern hobs have the following power ranges:

• 🔥 Up to 3.5 kW - low power models (usually 2 burners) suitable for RVs with medium power inverters.
• ⚡ 3.5–7 kW - standard panels for apartments and houses that require a separate line.
• ⚡⚡ 7–10 kW and above - professional or induction panels, which are often connected to a three-phase network 380V.

In RVs and campers, panels are most often installed with a capacity of up to 3.5 kW, since more powerful devices require major upgrades to the electrical system (for example, installing additional batteries or a generator). However, even for low-power models Do not use standard car wires - they are not designed for such loads.

To approximately calculate the cable cross-section, you can use the formula:

I = P / U

where I - current strength in amperes, P - panel power in watts, U — mains voltage (220V or 380V). For example, for a panel with a power 3 kW under tension 220V the current will be 3000 / 220 ≈ 13.6 A. However this simplified calculation - actual current may be higher due to starting loads.

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2. Cable cross-section: table of power and current correspondence

In order not to make a mistake with the choice of section, be guided by Rules for the construction of electrical installations (PUE). According to them, for copper wires in household networks, the permissible long-term currents are as follows:

Core cross-section, mm²	Max. current for open wiring, A	Max. power at 220V, kW	Max. power at 380V, kW
1,5	19	4,2	11,0
2,5	27	5,9	15,9
4,0	38	8,3	22,4
6,0	46	10,1	27,3
10,0	70	15,4	41,6

Important! For RVs and campers, it is recommended to use a cable with cross-sectional margin of 20–30%, since vibrations and temperature changes accelerate the wear of insulation. For example, for a panel with a power 3 kW instead of 2.5 mm² it's better to take 4 mm².

Also consider core material:

• 🟠 Copper - the preferred option (lower resistance, higher permissible current).
• ⚪ Aluminum - cheaper, but requires a larger cross-section and is not recommended for mobile installations due to fragility.

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3. Number of cores: single-phase vs three-phase connection

The type of connection depends on the network to which you will connect the panel and its design. Let's consider both options:

Single-phase connection (220V) - The most common case for apartments, houses and RVs. Here it is used three-core cable:

• 🔴 Phase (L) - brown or red wire.
• 🔵 Zero (N) - blue wire.
• 🟢 Earth (PE) - yellow-green wire.

Three-phase connection (380V) - relevant for powerful panels (from 7 kW) in garages or workshops. Needed here five-core cable:

• 🔴🟡🟤 Three phases (L1, L2, L3) - brown, black, gray.
• 🔵 Zero (N) - blue.
• 🟢 Earth (PE) - yellow-green.

In RVs, a three-phase connection is extremely rare, as it requires a special generator or connection to an industrial network. However, if you are equipping a permanent garage with a powerful panel, this option may be worthwhile.

What happens if you confuse phase and zero?

If the phase and zero are connected incorrectly, the hob may not work correctly (for example, it may not heat at full power) or may not turn on at all. In the worst case, this will damage the panel electronics. This is especially critical for induction models with a sensitive control circuit.

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4. Cable type: which brand to choose?

Not all cables are suitable for connecting the hob. Optimal options:

For permanent installation (apartment, house, garage):

• 🏠 VVGng-LS — copper cable with non-flammable insulation, suitable for hidden and open wiring.
• 🏠 NYM — an imported analogue of VVG, with additional protection from moisture.

For mobile installations (van, camper):

• 🚐 PVS — flexible multi-core cable, resistant to vibrations.
• 🚐 KG — cable with rubber insulation, withstands temperature changes and mechanical loads.

It is strictly forbidden to use cables of the ShVVP or PVS type in RVs - they are not intended for stationary wiring and can melt under prolonged loads.

Also note flexibility class:

- Suitable for permanent installation single-wire core (hard cable).

- For mobile systems it is better to choose stranded core (flexible cable), since it breaks less during vibrations.

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5. Connection diagram: step-by-step instructions

Before starting work, make sure that:

Step 1: Select an outlet or terminal block

For powerful hobs (from 3.5 kW) standard household socket on 16A won't do. You will need:

• 🔌 32A socket (for single-phase connection).
• 🔌 40A socket or terminal block (for three-phase connection).

Step 2. Connecting the cable to the panel

There is a terminal block on the back of the hob. The connection diagram depends on the type of network:

• 🔹 Single-phase network (220V): phase (L) connect to the terminals L1, L2, L3 (connecting them with jumpers), zero (N) - to the terminals N1, N2, earth (PE) - to grounding.
• 🔹 Three-phase network (380V): phases L1, L2, L3 we connect to the corresponding terminals without jumpers, zero and ground - similarly.

Step 3: Check connections

After connection:

1. Test all wires with a tester to check for short circuits.
2. Make sure there are no exposed wires.
3. Close the terminal box with a cover.

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6. Common mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes when connecting hobs. Let's look at the most common ones:

❌ Error 1: Wrong cable section

Using a cable that is too thin will cause it to overheat. For example, for a panel with a power 7 kW cable 2.5 mm² will be overloaded (minimum required 6 mm²).

❌ Error 2: Lack of grounding

Grounding is often overlooked in RVs, but it's dangerous! If the insulation breaks down, the panel body may become energized. In mobile systems, the ground is connected to the vehicle chassis.

❌ Mistake 3: Using twists instead of terminals

Twists oxidize over time, especially under vibration conditions. All connections must be made via terminal blocks or solder connections.

⚠️ Attention! Campers and RVs should not use aluminum wires to connect cooktops. Vibrations lead to rapid destruction of aluminum strands at joints.

❌ Error 4: Connecting via an extension cord

Many "temporary" solutions (for example, connecting the panel through an extension cord) become permanent. This leads to overheating of the contacts and the risk of fire. The hob must be connected directly via a separate line.

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7. Features of connection in a campervan

Connecting a hob in a van or camper has its own nuances:

🔋 Power supply

In most cases, the panel is connected via inverter (converts 12V/24V in 220V). Important:

• 🔋 The inverter power should be at 20–30% higher panel power.
• 🔋 For panel 3 kW you need an inverter for at least 3500–4000W.
• 🔋 The inverter must be pure sine (pure sine wave), otherwise the induction hob may not work.

🔌 Cable laying

In the confined space of a van the cable must be:

• 🛡️ Protected from mechanical damage (for example, laid in corrugation).
• 🔥 Resistant to high temperatures (insulation should not melt when the panel heats up).
• 🌀 Have a length reserve for moving elements (for example, if the panel is installed on a retractable table).

⚠️ Attention! If the hob is connected to the on-board network via an inverter, be sure to install fuse on the positive line next to the battery. Its rating must correspond to the maximum current of the inverter.

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FAQ: Frequently asked questions about connecting hobs

Is it possible to connect a 7 kW hob to a regular 16A outlet?

No, the standard socket is on 16A designed for maximum power 3.5 kW (16A × 220V = 3520W). For panel 7 kW you need a separate line with a socket on 32A or direct connection via terminal block.

What cable is needed for a 3.5 kW induction hob?

For induction hob power 3.5 kW with single-phase connection (220V) copper cable is suitable VVGng-LS 3×2.5 mm². However, in the camper it is better to take PVA 3×4 mm² with a margin of cross-section.

Can I use an aluminum cable to connect the hob?

Technically possible, but not recommended, especially in mobile installations. Aluminum is brittle, oxidizes in air and requires a larger cross-section compared to copper. To be safe, choose copper cable.

Do I need an RCD for a hob?

Yes, RCD (residual current device) mandatory for protection against leakage currents. For a hob, an RCD is usually installed on 30 mA and automatic on 25A or 32A (depending on power).

How to connect the hob to a three-phase network in the garage?

For three-phase connection (380V) a five-core cable is required (for example, VVGng-LS 5×4 mm²). Phases L1, L2, L3 connected to the corresponding terminals of the panel, zero (N) and earth (PE) — to your contacts. Be sure to check the phase rotation!