What cable is needed to connect the hob: selection, calculation, installation

A modern hob is a powerful electrical appliance that requires proper connection. Errors in cable selection can lead to overheating of the wiring, short circuit or even fire. This topic is especially relevant for owners of motorhomes and campers, where electrical panels are often installed in confined spaces with increased safety requirements.

Many motorists who equip the living compartments of their vans or trailers are faced with the need to connect the hob to the on-board network or an external power source. Unlike home conditions, it is important to take into account not only the power of the device, but also the features of automotive wiring, current limitations and the specifics of inverters.

In this article we will figure out what cable is needed for the hob depending on its power, type of connection (single-phase or three-phase) and operating conditions. You will learn how to correctly calculate the cross-section of wires, which brands of cables are suitable for automotive conditions, and what mistakes are most often made during installation.

1. Hob power: what determines the choice of cable

The first and most important parameter is hob power. The cross-section of the cable directly depends on it, which must withstand the load without overheating. Most modern panels have power from 3 kW (for compact models in motorhomes) up to 10 kW (for full-size induction cookers).

In automotive applications, power panels are more often used 1.5–3.5 kW, since they are compatible with inverters and on-board 12/24 V power supply. However, even such devices require proper connection. For example, induction hob Dometic Cooktop at 2.2 kW, if the cable is incorrect, it can cause voltage sags or trip the protection.

Key rule: The cable cross-section must correspond to the maximum current, which the panel consumes. To calculate, use the formula:

I (current, A) = P (power, W) / U (voltage, V)

For example, for the panel 3 kW under tension 220 V the current will be ~13.6 A. But this value must be multiplied by safety factor 1.2–1.3to take into account inrush currents and possible voltage surges in the vehicle network.

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

To avoid making a mistake with your choice, use the table for matching the hob power cable cross-section. The data is relevant for copper cable (in auto electricians, aluminum wires are not used due to fragility and poor flexibility).

Panel power, kW	Current at 220 V, A	Minimum cable cross-section, mm²	Recommended cable brand
1,5–2,5	6,8–11,4	1,5	PVA 3×1.5, ShVVP 3×1.5
2,5–3,5	11,4–15,9	2,5	PVA 3×2.5, VVGng 3×2.5
3,5–5,5	15,9–25	4,0	PVS 3×4, KG 3×4
5,5–7,5	25–34	6,0	KG 3×6, VVGng-LS 3×6
7,5–10	34–45	10,0	KG 3×10, PVS 5×6 (for 380 V)

Please note: Motorhomes often use flexible cables (for example, KG or PVS), as they are better able to withstand vibrations and frequent movements. Suitable for permanent installation in a garage or workshop VVGng - it is cheaper and more reliable in conditions of constant use.

⚠️ Attention: If the hob is connected via an inverter, the cross-section of the cable from the battery to the inverter must be 20–30% morethan from the inverter to the panel. This is due to voltage losses during conversion.

3. Cable brands: which one to choose for cars and garages

Not all cables are created equal for connecting hobs, especially in a caravan or garage environment. Here are the most common brands and their features:

• 🔹 PVS (Vinyl connecting wire) - flexible, multi-wire, ideal for moving connections. Suitable for connecting the panel to an outlet or inverter. Minus: does not like high temperatures (maximum +70°C).
• 🔹 KG (Flexible cable) — withstands up to +180°C, resistant to vibrations. Ideal for motorhomes where the panel may become hot or subject to mechanical stress.
• 🔹 VVGng (vinyl flexible non-flammable cable) - tough but reliable. Suitable for permanent installation in a garage. Not recommended for cars due to low flexibility.
• 🔹 SHVVP (flat vinyl cord) - cheap and flexible, but not designed for high loads. Can only be used for panels up to 2 kW.
• 🔹 PUGNP (Universal flexible wire) — an outdated brand, not recommended due to low reliability. It's better to replace with PVS or KG.

For motorhomes the best choice is KG or PVS with a cross-section 1–2 mm² larger than the calculated one. For example, for the panel 3 kW take it KG 3×4, not 3×2,5. This compensates for possible voltage surges from the generator or inverter.

4. Single-core or multi-core cable: which is better for the hob

Most often used in auto electrics multi-core cables (for example, PVS or KG), since they:

• 🔄 Flexible - do not break with frequent bending (relevant for motorhomes).
• 🛡️ Resistant to vibrations - insulation does not crack.
• 🔌 Easier to connect to the terminals of inverters and sockets.

However, they have a disadvantage: more resistance Compared to single-core cables (e.g. VVG). This means that with the same cross-section, a multi-core cable will heat up more. The solution is to take the cross section with a margin.

For permanent installation in a garage, you can use single core cable (for example, VVGng 3×4). It is cheaper and conducts current better, but is not suitable for conditions where mechanical stress is possible.

⚠️ Attention: If you connect the hob to three-phase network 380 V (relevant for powerful stoves in workshops), use four- or five-core cable (for example, VVGng 5×4). In auto electrics, a three-phase connection is rare, but if your camper is equipped with such a generator, do not forget about correct phasing.

5. Connecting the hob: step-by-step instructions

Now let's figure out how to properly connect the hob to the power supply. The instructions are universal for motorhomes, garages and workshops, but take into account the specifics of each case.

Make sure that the mains voltage matches the panel requirements (220V or 380V)|

Check the maximum power of the inverter (if connected via 12/24 V)|

Choose a cable with a cross-section 20% larger than the calculated one |

Prepare tools: crimping pliers, tester, electrical tape, terminals|

Turn off the power before starting work (remove the fuse or disconnect the battery) -->

Step 1. Selecting a connection diagram

• 🔌 Single-phase connection (220 V) - standard for most motorhomes. Used three-core cable (phase, zero, ground).
• 🔌 Three-phase connection (380 V) - relevant for powerful panels in garages. Required five-core cable (3 phases, zero, ground).

Step 2. Connecting the cable to the panel

There is a terminal block on the back of the hob. It is usually marked:

• L - phase (brown or red wire).
• N - zero (blue wire).
• PE - ground (yellow-green wire).

For three-phase connection there may be terminals L1, L2, L3. In this case, the phases are distributed evenly (for example, one burner per phase).

Step 3: Connect to an outlet or inverter

Often used in motorhomes special sockets for hobs (for example, Legrand or Schneider Electric at 20–32 A). If the connection is via an inverter, make sure that:

• 🔋 Inverter supports peak loads (for example, a 3 kW panel requires a minimum 3.5–4 kW inverter).
• 🔌 The cable from the battery to the inverter has a cross-section of at least 25–35 mm² (for 12 V) or 16–25 mm² (for 24 V).

What happens if the hob is connected incorrectly?

If you choose a cable with an insufficient cross-section, it will heat up, which will lead to melting of the insulation and the risk of a short circuit. If the phasing of a three-phase panel is incorrect, a phase imbalance is possible, which is why some of the burners will work weaker, and some will overheat. In RVs, it can also cause the inverter protection to trip or even damage the battery due to over-discharging.

6. Frequent errors when connecting the hob

Even experienced car enthusiasts sometimes make mistakes that can lead to panel failure or fire. Here are the most common:

• ❌ Using aluminum cable - in auto electrics this is unacceptable due to the risk of oxidation and poor contact.
• ❌ Connection via a regular 16 A socket - it is not designed for currents exceeding 3.5 kW. More powerful panels are needed 20-32 A power outlet.
• ❌ Lack of grounding — in a motorhome, grounding can be done through the chassis, but be sure to check the circuit with a tester.
• ❌ Ignoring inrush currents — when turned on, induction panels consume 1.5–2 times more than the nominal value. This must be taken into account when choosing an inverter.
• ❌ Twists instead of terminals — under vibration conditions, the twists quickly weaken. Use crimp sleeves or solder connections.

Critical error: connecting a hob with a power of more than 2 kW to the cigarette lighter or a standard on-board socket. This will lead to melting of the contacts and possible fire!

7. Additional accessories for secure connection

In addition to the cable, for a reliable and safe connection of the hob you may need:

• 🔌 Power socket and plug (for example, Legrand 32A or ABB 20A) - for panels with power from 3.5 kW.
• 🛡️ Difavtomat or RCD — protects against current leakage (especially important in motorhomes with a metal body).
• 🔧 Terminal blocks - for reliable connection of cables (for example, Wago 222 or screw terminals).
• 🔥 Heat shrink tube - for insulating connections at high temperatures.
• ⚡ Pure sine inverter - required for induction panels (a modified sine wave can damage them).

In motorhomes it is also recommended to install separate fuse to the hob line. For example, for the panel 3 kW the fuse will fit 20–25 A.

FAQ: Frequently asked questions about connecting hobs

Can a 3.5 kW hob be connected to a regular outlet?

No, a standard 16 A socket is rated for a maximum of 3.5 kW, but only under ideal conditions (high-quality wiring, no other loads). In reality, during prolonged operation, the socket and plug will heat up, which will lead to melting. For a 3.5 kW panel you need 20–25 A power outlet and a separate line with a cable with a cross-section of at least 2.5 mm².

What cable is needed to connect the hob via an inverter from a battery?

When connecting via an inverter, it is important to consider two areas:

1. From battery to inverter - the cable cross-section must be 25–50 mm² (depending on panel power and 12/24 V voltage). For example, for a 2 kW panel and a 12 V battery you need a cable 35 mm².
2. From inverter to panel - cross-section as for a regular 220 V network (see table above).

Also make sure that the inverter outputs pure sine (required for induction panels) and has a power reserve of at least 20%.

How does connecting an induction panel differ from a conventional electric one?

Main differences:

• 🔹 Induction panels require pure sinusoidal current (a modified sine wave from cheap inverters will damage it).
• 🔹 They have higher starting currents (1.5–2 times higher than the nominal value), so the cable and inverter must be spared.
• 🔹 Sensitive to grounding quality - if the grounding is poor, errors may occur or shut down.

Can I use an extension cord for my hob?

Use an extension cord for the hob highly not recommended, especially in a motorhome. If you cannot do without it, follow the rules:

• 🔌 The extension cord must be with a cross-section of at least 2.5 mm² and no more than 3 meters long.
• 🔌 Use extension cord with grounding and a 16–25 A plug/socket.
• 🔌 Do not twist the cable - this leads to overheating.

Ideally, the hob should be connected directly via a separate line.

Do I need to install a separate machine on the hob?

Yes, separate circuit breaker required. It protects the cable from overload and short circuit. Recommendations:

• 🔹 For panels up to 3.5 kW - automatic 16–20 A (type C).
• 🔹 For a 3.5–5.5 kW panel - automatic 25 A.
• 🔹 For three-phase panels - a three-pole circuit breaker (for example, 3×16 A).

In motorhomes they also install RCD 30 mA for protection against current leakage.