Induction Hob Installation in Rotherham: Will Your Cooker Circuit Cope?

Induction hobs are brilliant. They’re quick, they’re easy to clean and they’re far more efficient than the old ceramic ones. The trouble is, they’re catching a lot of people out.

A really common call I get goes something like this. The new kitchen is nearly finished, the hob’s sat in its box, and somebody has just noticed the old cooker circuit might not be up to it. Or worse, it’s already been connected and the trip keeps going every Sunday dinner.

I’m Mat from MP Electrical, and I’ve been an electrician for over 25 years. Here’s what I’d want any homeowner in Rotherham to know before they buy or fit a new induction hob.

Quick answer

Many induction hobs are rated at around 7.2 to 7.4kW, which is a big load. An older cooker circuit, especially one shared with a separate oven, may not have the right cable, protective device or control unit for it. Get a qualified electrician to check the existing circuit before the hob is bought or fitted, so any upgrade can be planned rather than rushed.

What is a cooker circuit?

Most homes have a dedicated cooker circuit. That means one cable running from the consumer unit (your fuse board) to the kitchen, feeding only the cooking appliances and nothing else.

It’s separate from your kitchen sockets because cookers draw far more power than a kettle or toaster. Giving them their own circuit, with its own protective device, is the normal way to do it.

The cooker control unit or isolator

Somewhere near the cooker you should have a big switch, usually red, often marked “cooker”. That’s the cooker control unit or cooker isolator.

It lets you switch the cooker off safely without reaching behind it. Some older ones have a 13A socket built into the same plate, which you’ll see in plenty of kitchens around Wickersley, Bramley and Maltby.

Ideally the switch sits to the side of the hob, not directly above it, so you’re not leaning over hot pans to reach it.

Diversity explained simply

Diversity is the idea that you don’t use each ring of the hob and the oven at full power, all at once, for long periods. Thermostats cycle on and off. You might have two rings going and the oven warming up, but rarely everything flat out.

Electricians use recognised guidance to work out a realistic load for a cooker circuit. A commonly used rule of thumb from IET guidance takes the first 10 amps of the total load, adds 30 percent of whatever is left, and adds a bit more if there’s a socket in the control unit.

That’s why a cooker rated well over 32 amps on paper can often sit quite happily on a 32 amp circuit. Diversity is a design tool though, not a way to squeeze more onto a circuit than it can safely take.

Why induction hobs catch people out

A typical 7.4kW induction hob, running flat out, draws roughly 32 amps on its own.

Now add a separate electric oven of maybe 3kW or so on the same circuit. Even with diversity applied, you can end up closer to the limit of an older 32 amp circuit than you’d like, depending on the cable and how it’s run.

Older kitchens and older cables

Plenty of houses in Rotherham, Sheffield and Barnsley still have cooker circuits wired years ago for a basic freestanding cooker. Some were run in cable that’s fine for what it was feeding, but it may not suit a modern high power hob.

Things that can reduce what a cable can safely carry include:

• Being buried in loft insulation
• Being bunched tightly with other cables
• Long cable runs from the consumer unit
• Older protective devices such as rewireable fuses

Power management settings

Some induction hobs have a power management or power limiting setting that can cap the total draw. That can help on a borderline circuit.

It’s useful, but a setting can be changed later by someone who doesn’t know why it was set. I’d rather the circuit suits the hob in the first place.

“Just plug it in”

I hear this a lot from customers who’ve been told it by a retailer or a kitchen fitter. Some smaller hobs and compact ovens do come with a 13A plug, and that’s fine for what they are.

A full size induction hob is a different story. A 13A plug can carry around 3kW. If a 7kW hob is sat on a plug, it’s either been limited heavily or it’s being pushed well past what that plug and socket are designed for.

Signs somebody has bodged it include:

• A hob cable with a plug that’s been added on
• An extension lead behind the units
• A hob wired into a spur off the kitchen ring
• Connector blocks hidden in the cupboard

If you’ve got any of those, switch it off and give a local electrician a ring.

Oven and hob on one circuit or separate circuits?

Both can be fine. It depends on the appliances, the existing wiring and the room in your consumer unit.

Sharing one circuit

A single oven and hob can share a properly designed cooker circuit, usually through one cooker control unit feeding both. This is common and perfectly acceptable when the numbers work out.

Separate circuits

With a big induction hob, it often makes sense to give the hob its own circuit and run the oven separately. Many built in single ovens are designed to run from a fused connection unit, which can sometimes be taken from a suitable circuit.

We’ll look at the manufacturer’s instructions for both appliances before deciding.

Cable size checks

Cable size isn’t a one size fits all answer. For many domestic cooker circuits you’ll see 6mm² twin and earth, and for heavier loads or longer runs 10mm² may be needed.

The right size depends on the load, how the cable is installed, how long it is and the protective device. That’s worked out on site, not guessed.

Range cookers

Range cookers deserve their own mention. A big dual fuel range might only need a modest supply, but an all electric range with an induction top and two or three ovens can be a serious load.

Before a range cooker arrives, check the rating plate or the installation manual and get the circuit looked at. Across Doncaster and the rest of South Yorkshire, it’s a common story for a range to turn up before anyone has checked the supply.

Signs your cooker circuit is struggling

Don’t ignore these:

• The cooker isolator feels warm or hot to the touch
• A burning or “hot plastic” smell near the switch
• Brown or black marks on the switch plate
• The trip or fuse going when the hob and oven are both on
• Crackling or buzzing from the control unit
• The hob showing error codes or cutting power

When I take the faceplate off a struggling isolator, it’s often loose or scorched terminals I find. Loose connections on heavy loads get hot, and heat makes them worse over time.

If you notice any of these, stop using the cooker and get it checked. Electrical Safety First’s kitchen safety advice also suggests getting burn marks or buzzing from sockets and switches looked at by a qualified person.

Why your electrician should look before you buy

This is my biggest bit of advice. Get the circuit checked before the new hob is bought, or at least before the kitchen fitter starts.

It’s far easier to run a new cable while the units and worktops are out.

When we come out, we’ll usually look at:

• The existing cable size and route
• The protective device in the consumer unit
• The cooker control unit and its connections
• Whether there’s RCD protection
• The ratings of the hob and oven you’re planning

If the fuse board is old or has no spare space, that may need sorting too. Our consumer unit upgrades include a fire extinguisher fitted inside the unit as standard, with options for surge protection and individual RCBO protection so one fault only takes out the one circuit. There’s more on those devices in our blog, RCD, RCBO, AFDD and surge protection explained.

What about Building Regulations?

In England, fitting a new circuit is notifiable work under Part P of the Building Regulations, as set out in Approved Document P on GOV.UK. As a NAPIT registered electrician in Rotherham, we can self certify that work and you’ll receive the paperwork.

Simply swapping a like for like cooker on an existing, suitable circuit is often a smaller job. Either way, the circuit should be checked as fit for the new appliance.

Frequently asked questions

Can I plug an induction hob into a normal socket?

Some small or two ring induction hobs are designed for a 13A plug. Most full size hobs aren’t, and should be connected to a suitable cooker circuit.

Will my old cooker circuit handle a new induction hob?

It might. It depends on the cable, the protective device, how it’s installed and what else shares the circuit. It needs checking by an electrician before you know for sure.

What size cable does an induction hob need?

Often 6mm², sometimes 10mm², depending on the load, the cable route and length. Your electrician will work it out on site.

Can the oven and hob share one cooker circuit?

Often, yes, if the combined load and wiring suit it. With larger induction hobs, separate circuits can be the better option.

How much does it cost to upgrade a cooker circuit?

Jobs vary, so we quote properly after we’ve had a look. It’s free to ask.

Related services and guides

• Kitchen electrics
• Consumer unit and fuseboard upgrades
• Small electrical jobs
• RCD, RCBO, AFDD and surge protection explained
• Electric showers: what a proper install involves

Contact MP Electrical

If you need help with an induction hob installation, a cooker circuit or any electrical work in Rotherham or South Yorkshire, MP Electrical are happy to help.

📞 Call our office on 01709 645115

🌐 Visit: rotherhamelectrician.co.uk

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