32A vs 40A vs 45A Cooker Circuits: What’s the Difference?

If you’ve opened your consumer unit and seen a breaker labelled ‘Cooker’, you might have noticed it’s rated 32A, 40A, or 45A. Or maybe yours just says 16A and you’re not sure if that’s enough. Here’s what the numbers actually mean and which one you need — plus what to do if your circuit isn’t big enough.

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The Quick Answer

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For a standard freestanding electric cooker in a typical UK home, 32A is the minimum. Most modern cookers and induction hobs are better served by a 40A or 45A circuit. Here’s why — and what the practical difference actually is.

What the Ratings Mean in Practice

The amp rating of your cooker breaker tells you the maximum current the circuit is designed to carry continuously. Multiply it by 230V (the UK nominal voltage) and you get the maximum power the circuit can deliver.

32A Circuit — The Entry Level

• Max continuous power: 7,360W (32A × 230V)
• Cable: 6mm² twin-and-earth
• Suitable for: Smaller freestanding cookers with ceramic hobs, older cookers, or cookers with a gas hob and electric oven

A 32A circuit will comfortably run a typical 4-zone ceramic hob with the oven and grill in use. However, some modern induction hobs with ‘boost’ functions can momentarily draw more than 32A. If your induction hob has four zones all on boost simultaneously while the oven is heating up, the 32A breaker may trip. That doesn’t mean anything is broken — it means the circuit is doing its job.

Important: A 32A circuit is adequate for the majority of standard freestanding electric cookers sold in the UK. Most manufacturers design their cookers to work within a 32A supply, especially models with ceramic (rather than induction) hobs.

40A Circuit — The Sweet Spot

• Max continuous power: 9,200W (40A × 230V)
• Cable: 6mm² or 10mm² (depends on cable length, routing method, and installation conditions — your electrician will calculate this)
• Suitable for: Most modern induction cookers, ovens with multiple heating modes, fan-assisted+conventional combos

This is the rating we recommend for most people buying a new cooker in 2026. A 40A circuit handles four induction zones on boost, plus the oven at 250°C, plus the grill, all running simultaneously. You have significant headroom, so you won’t experience nuisance tripping.

The cable question is worth understanding: in ideal clipping conditions (cable clipped direct to a surface with good air circulation), 6mm² cable can handle up to 47A. But if the cable is buried in insulation or runs through a long conduit, its current-carrying capacity drops. Your electrician will calculate the “reference method” and decide whether 6mm² or 10mm² is needed for a 40A circuit.

45A Circuit — The Heavy Lifter

• Max continuous power: 10,350W (45A × 230V)
• Cable: 10mm² twin-and-earth (6mm² is generally not sufficient for 45A except in very specific installation conditions)
• Suitable for: Large induction cookers (over 7kW), range cookers with multiple ovens, high-end appliances, and households that cook large meals regularly

A 45A circuit is future-proof. If you’re planning to install a high-end induction range cooker or a dual-fuel model with a large electric oven and induction hob, this is the rating you want. It gives you enough headroom that you can run everything at maximum without thinking about load management.

How to Tell What You’ve Got

Open your consumer unit door (just the outer door — do not remove the inner cover). Look for a switch labelled ‘Cooker’. The current rating is printed on the front of the MCB — usually 32, 40, or 45. If it’s 16 or 20, that’s not enough for a full-size cooker.

If you don’t see a cooker breaker at all, check our step-by-step guide to finding your cooker circuit.

Can You Upgrade From 32A to 40A or 45A?

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Not by just swapping the breaker — and never do this. Here’s why:

The cable size is the limiting factor, not the breaker. A 32A circuit uses 6mm² cable, which has a maximum safe current-carrying capacity that depends on how it’s installed. Swapping to a 40A breaker without verifying the cable can handle that current creates a genuine fire risk — the cable could overheat while the breaker never trips.

Your electrician will:
1. Inspect the existing cable size (6mm² or 10mm²)
2. Calculate the current-carrying capacity based on length, routing, and installation method (buried in insulation, clipped direct, etc.)
3. Check whether the cable can safely handle the new breaker rating
4. If not, recommend a cable upgrade (which means chasing walls or lifting floorboards — hence the extra cost)

A cable upgrade typically costs £200–£400 on top of the breaker swap. A full new 40A circuit from scratch (including cable run, MCB, and isolator) costs £300–£600, so sometimes it makes more sense to run a new cable if the existing one is borderline.

The Diversity Factor — Why Your Cooker Probably Draws Less Than You Think

There’s an important concept in BS 7671 called diversity (or “demand factor”). The regulations recognise that you’ll never have every single heating element in your cooker running at maximum simultaneously. In practice:

• The first 10A of the cooker’s total load is counted at 100%
• 30% of the remaining load is added
• Any socket built into the cooker control unit is counted at 5A

So a cooker with a total connected load of 11kW (about 48A) would have a diversity-calculated demand of roughly 10A + (30% of 38A) + 5A = 26.4A. That’s well within a 32A circuit. This is why many 8kW–10kW cookers are perfectly happy on a 32A supply in normal use.

That said, diversity is a planning tool for electricians — it doesn’t guarantee your breaker won’t trip. If you regularly run every hob zone on boost with the oven at maximum, you’ll still hit the limit.

What Happens If the Breaker Is Too Small?

The breaker trips — that’s literally its job. If your 32A breaker trips when you turn on the third hob ring and the oven, it’s telling you the circuit isn’t big enough. Don’t replace the breaker with a bigger one without also upgrading the cable — that’s how cable overheating, melted insulation, and fires start.

A nuisance tripping scenario often sounds like this:

“I bought a new induction cooker and it keeps tripping the circuit breaker when I use more than two zones. I thought it was faulty, but the manufacturer says it draws 7.8kW at full load, and my circuit is only 32A. The electrician told me I need a 40A circuit with 10mm² cable. I didn’t budget for that. If I’d known beforehand, I would have bought a cooker with a lower total load, or stuck with my 13A plug-in model.” — Priya, Birmingham

The Bottom Line

If you’re installing a new circuit, spec it at 40A or 45A to future-proof for induction. If you’re stuck with a smaller circuit or no cooker circuit at all, don’t worry — modern 13A plug-in cookers and countertop appliances can handle the vast majority of everyday cooking without any rewiring.

For a full breakdown of what it costs to have a new circuit installed, read our guide to electric cooker installation costs.

The key takeaway? Most UK homes with a cooker circuit have 32A, and that’s fine for most cookers. But if you’re buying new — especially an induction model — it’s worth checking your breaker rating before you order. A quick look at your consumer unit now can save you the disappointment of a tripping breaker on Christmas dinner day.