Executive Summary

Part of the movement to all-electric houses is a push to install induction cooktop stoves. Depending on which stove you choose and how you use it, there may be significant electromagnetic field (EMF) emanations. Luckily the Swiss Federal Office of Public Health did an exhaustive study in 2011.

They are also very pricey, in the range of $2,000. You will have to replace your cookware. AllClad makes a cookware set “optimized for induction.” The 10-piece version will set you back $800. Add installation and you’ll probably end up in the vicinity of $4,000 total cost. (If you think you can just slide one of these into the stove slot and plug it into a wall outlet, you are mistaken.)

Read on for the details.

Introduction and Background

In July, 2019, Berkeley was the first California city to mandate electricity only in new residential construction.^[1] They were followed quickly by San Jose, Mountain View, Santa Rosa and Brisbane. Not to be outdone, Brookline, MA, implemented a similar ban.^[2] Many other cities are actively considering similar laws. Search on REACH codes if you have doubts.

The key to understanding this is that proponents of the natural gas ban would like to also mandate magnetic induction cooktops. These devices are marvelous to look at. No ugly exposed burners, just a sleek black glass top. But it will cost you quite a bit. And there are dangers.

 

Here, I’ll only discuss full stoves that include induction cooktops. There are alternatives, the induction equivalent of a hotplate. Much of the advice in this article also applies to these devices.

Before getting into details, here’s a good summary of benefits and costs from Anne-Marie Nichols.^[3]

1. Cost. An induction cooktop stove can be pricey.
2. Installation. Your induction cooktop stove must be professionally installed.
3. Induction stove cookware. You’ll need pots and pans that work on your induction cooktop stove. [Actually there’s a workaround for this.]
4. Care and cleaning. It’s easy to take care of induction cooktop stove once you know how.
5. Heats food quickly. This is why so many cooks love induction cooktop stove cooking!

For better or worse, Ms. Nichols does not discuss a far more important issue, health risks. Let’s look at those first then (if you’re still interested) summarize likely costs.

Cook Carefully^[4]

These stoves emit low-level electromagnetic frequencies (EMF). They also conduct a bit of electric power, generally thought to be harmless. Most of the research has focused on EMF. Switzerland’s Federal Office of Public Health seems to have done the most definitive work on safety. In 2011 they selected three induction cooktops for testing. They chose two sets of cookware, induction cooking optimized and plain old cookware. In the vernacular, each cooking area is called a hob. They looked at situations where the cookware is properly centered on the hob as opposed to being off-center.

The European standard for EMF emissions is 6.25 microteslas (μT). This is called the reference value.

Here’s a quick summary. If you’re using appropriate cookware and have it centered on the hob, you only have problems with one model tested at less than 4 cm distance. This is about 1.6 inches. Most people don’t get that close. But for those who are height-challenged, maintaining an appropriate distance can be difficult.

On the other hand if you’re using inappropriate cookware and not centering it on the hob, one cooktop tested exceeded the standard if you’re closer than 17 cm (about 6.7 inches). For a second model the distance was 10 cm (3.9 inches). A third model remained below the reference point at all distances.

If your main concern is safety, cooktop 3 keeps EMF emanations below the European standard in all cases (tested to a distance of 1 cm). Meet cooktop 3, the Inducs SH/BA 5000. But you are likely to get better performance with 1 and 2 because they include a power booster function, absent from cooktop 3. More power means faster heating and more EMF.

That’s the quick version. The remainder of this section goes into the details of the testing. If you want to skip to the Price and Cost section click here.

Safety Details

The European standard for EMF emissions is 6.25 microteslas (μT). I’m not going to even try to explain that. Interested readers are invited to investigate this on their own. Start with the Appendix below. This is called the reference value. Exceeding this value raises safety concerns.

The testing itself was very complicated, with each of the four hobs being tested with and without the power boost. Let’s ignore those complicating factors. There are three main safety concerns that remain:

1. Not properly centering the cookware on the hob. Leaving part of the heating area exposed increases EMF exposure.
2. Not using induction-compatible cookware.
3. How close is the cook to the hob.

That means there are four combinations of cookware and positioning:

1. Induction compatible cookware centered.
2. Induction compatible cookware not centered.
3. Incompatible cookware centered.
4. Incompatible cookware not centered.

A summary of the results is below. Note that in all three graphs the horizontal axis is distance from the cooking surface. In all three graphs the horizontal line at 6.25 is the reference value. Finally, solid lines represent the “good” alternative while dashed lines are the “bad” option.  For example, in the first graph below the solid lines are for induction compatible cookware while the dashed lines are incompatible cookware.

Here’s what the Swiss researchers had to say:

Stray fields are larger the closer to the cooking field they are measured. At a distance of 30 cm, all models comply with the reference value of 6.25 microtesla (μT) recommended by the ICNIRP. In most cases the stray field measured 1 cm in front of the edge of the cooking zone exceeds this reference value. With an off-centre placing the stray field reached the reference value at a distance of < 1 cm to 12 cm with appropriate pans and < 1 cm to 20 cm with inappropriate pans. All measurements were carried out with the hob at the highest setting. A distance of 1 cm is unlikely to occur in normal daily use and represents a worst-case scenario. None of the measurements exceeded the ICNIRP reference value at a distance of at least 5 – 10 cm, the distance most likely to occur in practice, when the pans were used correctly (suitable cookware, centred over the cooking zone).

Those curious about the test environment (and numbering the hobs) should study the diagram below.  The position of the probe matches the location of the cook’s hands.

Enough engineering jargon. Let’s talk money.

Prices and Cost

These things are not cheap. Here are three models from Amazon.com (as of May 24, 2020).

• $1,292.00 GE PHP9036DJBB 36 Inch Cooktop with 5 Induction, 3,700-Watt Element, Pan Size Sensors, SyncBurners, Red LED Display, Kitchen Timer, ADA Compliant Fits Guarantee
• $2,063.10 GE CHP9536SJSS Cafe 36″ Gray Electric Induction Cooktop
• $2991.99 GE PHP9036SJSS 36 Inch Cooktop with 5 Induction, 3,700-Watt Element, Pan Size Sensors, SyncBurners, Red LED Display, Kitchen Timer, ADA Compliant Fits Guarantee

But that’s not all. You can’t just shove these things into the slot and plug them. Returning to Ms. Nichols’ advice,

If you’re replacing an electric stove top, it’s not just a matter of hooking it up to the old power source.

An electrician will need to run a 50 amp breaker with a #6 gauge Romex line (#8 minimum).

If there are any questions, the details and specs are in the installation book, so make sure to factor that into your budget.

When planning your installation costs with your electrician, you can usually find the installation instructions online before you order your stove.

Will the cooktop stove fit? Since the cooktop will need to be set into a countertop, you may need to work with countertop installers as well.

So that means working with an electrician and possibly a kitchen design shop (or, at minimum, a carpenter). According to FixR.com, the cost of installing an induction stove is between $700 and $2,000.^[5]

You’ll also need to replace all your stovetop cookware. In a minute, I’ll describe a workaround for this. But for now, let’s take a look at some induction-compatible pots and pans. Here’s one from Amazon.com.^[6]

This set is advertised as “Compatible with gas, electric, induction, and glass top stovetops.” Other sets are labeled “induction-ready.” In many cases it looks like the manufacturers have attached a magnetic steel plate to the bottom of their existing cookware line. Which will make your fancy new stove considerably less efficient. Honestly, there don’t seem to be many pots and pans built for induction from the ground up.

All-Clad offers a set that is “optimized for induction.”

One option that seems to save money (but doesn’t) is the induction converter.  This is essentially a magnetic steel plate you put over the hob.  You then put your conventional cookware on the plate.  Here’s what they look like.

And here’s one in use:

I’ll just point out that this probably eliminates most of the efficiency you gain from having an induction cooktop. The induction heats the plate. The plate, in turn, heats the pan. Sound familiar? It should. That’s how your current electric stovetop works.

Conclusion

Induction cooktops are expensive. Installation and replacing your cookware will probably double the cost. And there can be safety concerns depending on which cooktop you choose, the cookware, whether it is used properly, and how far you stand from the hob(s) being used. Caveat emptor.

Appendix

(If you got here by clicking the link in the text, click here to get back.)

Here’s some additional technical information on EMF from the World Health Organization.^[7]

Electric and magnetic fields exist wherever electric current flows – in power lines and cables, residential wiring and electrical appliances. Electric fields arise from electric charges, are measured in volts per metre (V/m) and are shielded by common materials, such as wood and metal. Magnetic fields arise from the motion of electric charges (i.e. a current), are expressed in tesla (T), or more commonly in millitesla (mT) or microtesla (µT). In some countries another unit called the gauss, (G), is commonly used (10,000 G = 1 T). These fields are not shielded by most common materials, and pass easily through them. Both types of fields are strongest close to the source and diminish with distance.

Most electric power operates at a frequency of 50 or 60 cycles per second, or hertz (Hz). Close to certain appliances, the magnetic field values can be of the order of a few hundred microtesla. Underneath power lines, magnetic fields can be about 20 µT and electric fields can be several thousand volts per metre. However, average residential power-frequency magnetic fields in homes are much lower – about 0.07 µT in Europe and 0.11 µT in North America. Mean values of the electric field in the home are up to several tens of volts per metre.

1. Tony Lima (July, 2019) GonzoEcon.com. “Berkeley Bans Natural Gas.” Available at http://gonzoecon.com/2019/07/berkeley-bans-matural-gas/ . Accessed May 24, 2020. ↑
2. Irina Ivanova (Dec 6, 2019) CBS News. “Cities are banning natural gas in new homes, citing climate change.” Available at https://www.cbsnews.com/news/cities-are-banning-natural-gas-in-new-homes-because-of-climate-change/ . Accessed May 24, 2020. ↑
3. Anne-Marie Nichols (2017) ThisMamaCooks.com. “5 things you need to know about an induction cooktop stove.” Available at https://www.thismamacooks.com/2020/01/induction-cooktop-stove.html . Accessed May 24, 2020. ↑
4. Most of the material in this section is from Federal Office of Public Health FOPH, 3003 Bern, Switzerland (November 11, 2011). “Induction Hobs.” Available at https://www.bag.admin.ch/bag/en/home/gesund-leben/umwelt-und-gesundheit/strahlung-radioaktivitaet-schall/elektromagnetische-felder-emf-uv-laser-licht/emf.html . Accessed May 24, 2020. A more technical version is Clementine Viellard, Albert Romann, Urs Lott, and Niels Kuster (2007). “B-Field Exposure From Induction Cooking Appliances.” Available at the same source. ↑
5. FixR.com (2020). “Cooktop Installation Cost.” Available at https://www.fixr.com/costs/cooktop-installation . Accessed May 24, 2020. ↑
6. Beware of Amazon. A search for “induction cookware” returns many items that are not induction compatible. Scroll to the bottom of the filters (left sidebar) and check “Induction.” Even then, a few strays show up. ↑
7. World Health Organization (2007). “Electromagnetic fields and public health.” Available at https://www.who.int/peh-emf/publications/facts/fs322/en/ . Accessed May 25, 2020. ↑