Remodelling and upgrading your kitchen can not only increase the resell value of your home, but it can also improve the functionality of your kitchen. One appliance to consider replacing is your hob. If you’re doing this job yourself, it’s crucial to know what size cable to use, lest you risk starting an electric fire.
The size of your cable depends on the energy usage of your electric hob. Induction hobs with 4-5 burners usually have a minimum circuit requirement of 40-50 amps, which requires at least a 10 mm cable. A too-small cable creates a fire hazard, but a cable too large is still safe.
It’s safe to assume that if you’re researching the correct size cables, you intend for this to be a DIY project. That’s fine, so long as it is done safely and legally. Read on to find more about choosing the correct cables, the hazards of using faulty electrical equipment, and how that can affect you legally.
Building Regulations and Part P
Most electrical work completed in homes in England and Wales must meet the Building Regulations introduced by the government in 2005. Part P dictates that electrical installation work must be completed by a competent (i.e., licensed and approved by the government) person, and the work must be certified as Part P compliant.
It may be a worst-case scenario, but if a guest in your home were to die due to your poor wiring, you would be liable for prosecution. In less extreme circumstances, you could pay a hefty fine (up to £5000.00) for your uncertified electrical work.
Installing an Electric Hob into An Existing Circuit
Notifiable work is electronic installation work that requires notification or sometimes full plans to be submitted to the local authority before installation. Certain jobs don’t require you to submit a notification to your local authority. The installation of an electric hob does not require notification so long as you’re installing the hob into a pre-existing circuit.
While you do not have to submit anything before, you do still have to have your work certified as Part P compliant. If you are a landlord, your rental properties are required by law to be inspected at least every five years. If you are a homeowner, you may think you’ll get away with it.
Is that a chance you want to take? The residence will have to be inspected if you ever intend to sell it. Also, if there is ever an accident resulting from this electrical installation, the lack of certification will void your homeowner’s insurance policy.
Installing a New Circuit for Your Electric Hob
If there is no pre-existing circuit or your current circuit does not meet your new electric hob’s power requirements, a new circuit must be installed. Any installation of a new circuit must be done by a Part P qualified electrician. Anything else is strictly forbidden.
Power Needs of Electric Hobs
Electric hobs draw a lot of current to produce the heat needed to cook your food. How much power depends upon your individual cooker. Using a “domino” hob with only two burners will require less energy than a hob with 4 or 5 burners. Knowing if your current circuit meets these needs lets you know if you need to hire an electrician to install a new circuit or not.
When purchasing your new electric hob, take a look at the total-unit power level. To find the amp requirement, divide the power (W) by the voltage (V). The standard voltage in the UK is 230 V at a rate of 50 Hz. This can fluctuate, but any appliance manufactured to European Standards are built to withstand voltage rises to 2000 volts for short durations.
A few examples of common maximum electrical load at 230 V include:
- 7.2 kW / 230 V = 31.2 A
- 9.6 kW / 230 V = 41.7 A
- 12.0 KW / 230 V = 52.1 A
The amps let you know if your current circuit is rated to withstand your new electric hob’s power needs. If it isn’t, you will have problems with tripping the circuit breaker when using your cooker. On the other hand, having a circuit that is rated too high may cause it not to trip if there ever is a problem.
Finding the Right Cable
When it comes to your cables, too large isn’t as much of a concern as too small. Granted, the larger cable will cost more, but the Copper Development Association reports that upsizing your wire will increase energy efficiency. This will lead to savings on your energy bill over time.
Think of the cable as a garden hose and the amps as the water pressure; after all, it is the measure of the current flowing through the cable. You would not attach your garden hose to a fire hydrant; it isn’t designed to withstand and accommodate that amount of water pressure. Just the same with cable, if it can’t accommodate the current flowing, it can overheat and start a fire.
For electric hobs that work on a 32A circuit, a 6 mm twin and earth cable should work just fine. However, if you look at the section above, a 7.2 kW @ 230 V electric hob will just cut it on a 32A circuit. Anything more than that will require a higher rated circuit and a larger cable. In most cases, 10 mm twin and earth cable will be your best and safest bet.
“Twin and earth” refers to the three wires inside your cable. There is the wire for the neutral current and a wire for the live current (the twins), and an exposed wire that returns residual current to the ground (earth). This is sometimes referred to as the ground wire.
A few tips before starting your electrical DIY:
- Know your cables and wiring. Cable colours have been standardized in the UK to help avoid confusion since 2006. Currently, the colours are as follows:
- Live wire – brown
- Neutral wire – blue
- Earth wire – green and yellow stripe
- Use a Cable Detector to Identify where your cables are. Avoid the common mistake of accidentally locating these cables in the wall by drilling, nailing, screwing, or cutting into them.
- Cut the power – If you’re working with electricity, shut the power off before you start. Use battery-powered tools. This will decrease the risk of electric shock
- Test for Power Using Voltage Detector – Even after you’ve shut power off at the breaker, ensure there is no power using an approved voltage detector.
Depending on the electric hob you’re installing, you will likely need either 6 mm or 10 mm twin and earth cable. It won’t hurt to have a cable that’s too thick, but it can hurt to have a cable that’s too thin.
When installing your electric hob, whether into an existing circuit or if you’re installing a new circuit as well, you want to do so safely. It’s more than a want; it’s a legal imperative. If you’re in any doubt if you’re using the correct sized cable, consult with a Part P certified electrician. Doing so can save you a lot of trouble in the long run.