Do Induction Cooktops need special wiring?

Do Induction Cooktops need special wiring

Induction cooktops need to be plugged into a power source as it uses electricity to work. And this brings us to the question whether induction cooktops need special wiring to work or not.

The answer to this is yes and no.

It depends on the type of wiring that is present in your home and the model of induction you have. While most induction cooktops work with regular wiring, you may need special wiring if there is a specific voltage or amperage requirements.

Special wiring is needed when you want to increase amperage capacity or when the demands of induction are more than what is being supplied.

It basically boils down to understanding the electric requirements of the Induction cooktop. We do know that induction works on the principle of electromagnetism. An alternating current is passed through a copper coil which creates a magnetic field. Now for the current to be passed, inductions require electricity.

Electric requirements of Induction

In the United States, an induction cooktop requires a dedicated, grounded 240-volt circuit protected with a 40-50 amp breakers that terminate in an approved junction box mounted near the cooktop. This could be either below the counter near the back of the cabinet or on the wall behind it.

The junction box should be a good distance away from the cooktop so that the connections inside the box are not exposed to excessive heat.

Most manufacturers supply a length of flexible armored cable to connect the cooktop to the home wiring at the junction box.

Things to keep in mind before wiring

There are few things to keep in mind before wiring the cooktop induction.

Firstly you must know the local building codes. The installation must comply with the national electric code. The correct voltage, frequency, and amperage must be supplied to the appliance from a dedicated grounded circuit. The circuit must be protected by a properly sized circuit breaker or time-delay fuse.

Next, you need to know whether the power supply is three or four wires. Do local codes permit grounding through neutral. And lastly, whether your house has aluminum wiring. This is because the cooktop has copper wiring and for it to connect to aluminum wiring requires special connectors.

Electric conduction in detail

For the current to flow properly and reach the induction, it has to flow through a wire.

The wire should have some resistance for the current to flow in a particular direction or else a little pressure would send the current in any direction. The resistance ensures the electric current flows in a particular way.

This resistance is given by the material of the wire. Some carry electricity with little opposition and some with a lot of opposition or, in other words, with great resistance. The energy the current loses in overcoming this resistance is given off as heat.

Wiring in homes

Even though the wires carrying electricity in the walls of your house are excellent conductors, they are of a particular diameter and give some resistance to the flow of electricity.

This resistance builds up as heat. And that is why the size of the wire is set rigidly by building codes to match the maximum amount of current the particular sized wire is allowed by law to carry. This way no in-wall wire will ever get hot enough to trigger a fire.

Apart from having codes and regulations for the wire size (the maximum current is set by the size of the installed wire), the law also requires the presence of a device that will instantly break the circuit if ever the allowed maximum increases. In olden times, this device was a fuse.

The fuse was a one time use device consisting of a small metal strip, enclosed in a glass, designed to melt and thus break open at the maximum current it is rated for. Example – 15amp fuse. Nowadays circuit breaker is used which can be used indefinitely, one can just reset if it trips open.

Another thing to keep in mind if you are in the wiring phase of your home, aluminum wiring possesses serious dangers. The reason is that although it can carry the current it is rated for, aluminum expands and contracts with heat much more than copper and tend to loosen connections at screw terminals from repeated expansion/contraction.

This creates high resistance that can overheat, cause sparking and start a fire. This is the reason installing aluminum wiring is now illegal in many places.

Wiring for Induction Cooking

If you are in the design stages you need to set up wiring adequate to the electrical demands of your induction and if wiring is already there then you need to restrict yourself to an induction which does not demand more than your wiring can supply.

Explaining in simple algebra, the current flow in amps is the power divided by voltage. This will give you the required ampacity ( current carrying capacity ) for your in-wall wiring. In other words load requirement for the circuit.

In the USA, supply circuit capacities in amps typically start at 15amps and then tend to run in multiples of ten:20,30,40 etc.

Older homes in the USA had 150 amp main house panels. That meant that the entire house could take no more than 150amps from the power company. Newer houses are built with 200amps service.

Now, the size of wire is equally important in carrying a specific amount of ampere or current. The local codes for your area usually specify the gauge. Some near-standard values to give you a rough idea are :

  • 14 gauge can carry 15amps
  • 12 gauge can carry 20amps
  • 10 guage can carry 30amps
  • 8 guage can carry 50amps
  • 6 guage can carry 65amps

I would recommend and 8 gauge wire if you are wiring or rewiring your house. But check with local codes beforehand. 

This would give you a dedicated 50amps for your induction cooktop.

Knowing the voltage you have to deal with and the ampacity you will have available, you can calculate the minimum power you will be able to supply to your induction cooktop and choose the induction unit accordingly. A good formula to remember is P= V* I.

Your Judgement Call

Now, knowing the power you will be having at hand, if your power is just a little less than the unit you are interested in seems to need, (example 7.2kw and your unit needs 7.4 kW) then you have to make your own call.

Will you or not go ahead. What you can do in such a case is not use all the elements on full power simultaneously. The worst that can happen is that you can trip the circuit breaker. On the other hand, you don’t want to be tripping the breaker very often.

Lastly, make sure you know how much each element in your induction can draw when setting to a maximum. Then make sure that is within the limit that you have calculated.

Connecting induction wires and its methodology

To prevent an electric shock or fire hazard, turn off power to the circuit at the circuit breaker panel or fuse box before connecting the cooktop wiring.

Connect the ground wire (usually green) from the appliance to a grounded, metallic, permanent wiring system. It is better not to connect the ground wire to a neutral house supply wire. In many places, this is prohibited.

If aluminum house supply wiring is utilized, connect the appliance copper wires to the aluminum house wiring using special connectors designed and agency certified for joining copper with aluminum.

Follow the manufacturers written procedure properly. Improper connection may result in a fire hazard.

The cable from the appliance may have three wires or four wires. In some areas connecting neutral wire of junction to ground wire of appliance is permitted and in some areas, it is not permitted. Depending on your local area codes, connect with junction box accordingly. Follow the manufacturers’ instructions carefully.

Below I have mentioned an example of how to connect a three-wire cable with the external ground ( in such places local area codes do not permit connecting to the neutral wire in the junction box).

Three-wire electrical connection cable with external ground

For grounding, do not ground the appliance to a gas supply pipe or a hot water pipe. If connecting to a grounded cold water pipe, connect it using a separate copper grounding wire (no. 10 minimum) and a clamp with an external grounding screw.

The grounded cold water pipe must have metal continuity to electrical ground and must not be interrupted by insulating materials. Any insulating material must be jumped with a minimum 4 AWG wire to establish continuity to ground.

Do note that if the junction box has been properly grounded by a licensed electrician, the ground wire ( green) may be connected to the junction box using a loop terminal.

Connect the black wire from the appliance to the black supply wire in the junction box.

Similarly, connect the red wire from the appliance to the red supply wire in the junction box.

Read the manufacturers instructions carefully and comply with local area codes in your city before setting up the wiring for your induction. I hope I have given you a deep understanding of wiring required for induction and have simplified its aspect for you. Good luck!

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