Induction Hobs

Good evening, I had my pacemaker fitted on Wednesday morning, by the afternoon I was back having a lead redone as it had moved. Not a very nice experience. However I asked the cardiac technician whether it is safe to use my induction hob which is 7 years old and he said no. So I have done research and get conflicting results.
Has anyone come across this problem, if so your advice would be appreciated.

28 Comments

Hi Angelcat

by IAN MC - 2014-05-02 04:05:44


A few weeks ago I was in a neighbour's house and I was standing very close to their induction hob. My pacemaker started furiously beeping , I walked away and the beeping stopped, I walked nearer and the beeping re-started.

I wrote to the Medtronic HQ here in the UK , asking for an explanation and received this reply :-

"Thanks for your query.

As I'm sure you know induction hobs contain a strong magnet, which can also
interfere with implantable devices - a strong magnet is also used to initiate
the telemetry in your device when you have it interrogated in clinic. So it
sounds like you perhaps got a bit too close to the induction hob and the magnet
in it affected the device temporarily. It is highly unlikely to have caused any
damage to the device, but you may want to contact your follow up centre for
reassurance if you are concerned.

I hope this helps to explain things.

Best wishes,

Becky "

I replied to them and asked " But why did my PM make a beeping noise, is it a warning not to get too close , or what ?" So far, Becky has not replied !!

I am interested to read any replies.

Ian

Induction hobs

by Angelcat - 2014-05-02 04:05:46

That is very interesting Ian, I feel reluctant to get near our hob while it is on until I hear anything to the contrary. Did you just get beeping or did you feel anything else? Let me know if Becky replies.
Wonder if anyone else has had any effects.
Di

Only beeping !

by IAN MC - 2014-05-02 05:05:17

I didn't stay there long enough to find out if I'd collapse, burst into flames or start frothing at the mouth !

The beeping was quite scary as it was totally unexpected

Ian


Ian: Beep! Beep!

by donr - 2014-05-03 03:05:04

I just went & downloaded the Advisa manual & could find nothing in it about Beeping.

I went through every page in the index & found nothing even remotely related to it making a sound.

Sorry, I cannot help - BTCOOM!

You sure there wasn't a US "Roadrunner" animated cartoon playing on the TV in the background?

Don

I use mine all the time.

by Harrie - 2014-05-03 04:05:53

The Biotronik tech told me not to use it because they have no way of knowing the strength of the magnet. I avoided it for a few weeks but when I asked the cardiac tech at the clinic he looked it up somewhere and said it was fine as long as I didn't lean over it, and to move away if I felt anything. I 've been using it without any problems for 10 months. Try it and see.

Induction

by Angelcat - 2014-05-03 05:05:00

Thank you Royale, I think I will give it a try and see how it goes. I am starting to improve in the pain department, I don't recommend having a PM done twice! I am being really careful so the leads have a chance to embed themselves in.

Watch out for that coyote!

by donr - 2014-05-03 05:05:01

Ian: I found an article on line that may explain what you hear. ONLY a theory at this point.

I was wondering if there was some electrical oscillation in a circuit that caused part of the hob to resonate w/ a sound that you interpreted as a "Beep" coming from your PM. Turns out that it is a distinct possibility.

This would depend on ow acute your hearing is & what kind of upper limit to high frequency sounds you could hear. I know that back when I was teen in the 1950's, I could hear the "Whistling" sound from the "Flyback" transformer in a US TV set that was oscillating at 15,000 (Roughly) Hz. No one else in my family could hear it.

Some UK EE bought a cheap Induction heating hob & disassembled it, checking the electrical waveforms inside it. He found that there were some that I described as "High," but not high enough to cause radiation from the hob. They were "Square waves" at about 24,000 Hz. That's usually above the range of the human ear - but it will vary from hob to hob & the wave forms are nowhere near clean & precise in their shape, so there may well be lower frequencies generated that you can hear as a distinct "Beep," or as I described it in my callow youth, a "whistle."

It would NOT be very loud, so you would have to get close to hear it - perhaps creating the illusion of it coming from your PM. Especially if you got close enough that you leaned over the hob somewhat & it began to sound like it was coming from the PM, when in reality it was coming from the guts of the hob.

Hope this makes some sense to you.

I'd like to invite KAG to read this over & give another geek's opinion from the EE perspective.

Donr

I'm sure lots of people do !

by IAN MC - 2014-05-03 05:05:01

I didn't mean to scare you out of not using it , Angelcat, because millions of people have induction hobs and lots of those people will have PM implants so as Royale says try it and see and what happens !

I certainly would't lie on top of it for hours on end but I'm sure you will be perfectly safe with normal usage !

Having said that I am always intrigued by statements such as the one from Medtronic that " it affected the device temporarily " as though that is perfectly OK.

I don't want my device affected temporarily; I want it working all of the time 24/7.

My sinus node can cause my heart rate to plummet at the most unexpected times to 20 bpm and lower which is why I have a PM.

I can't help wondering what would happen if my HR was having one of its plummeting spells at the precise moment that " my device was being affected temporarily " by an induction hob or any other magnetic device . Is there the potential for me to collapse ?

Could some engineering guru put my mind at rest; donr, where are you ?

Ian

Ian, I'm here...

by donr - 2014-05-03 11:05:06

From what I know about induction hobs, I'd vote w/ Royale on safety. UNLESS, of course, there is an individual whose PM is more sensitive or has defective shielding in it.

There should be no permanent magnets in the device, since you cannot induce an electric current in another close-by conductor (Read that as the bottom of the cooking vessel).

The Hob is nothing more than a fancy primary winding for a transformer. Meaning that it generates a time varying magnetic field above it. IIRC, the system works at much higher frequencies than the 50 Hertz of your house power, but not high enough to radiated a lot of energy like a radio transmitter. Without a pot w/ a conductive bottom sitting atop the hob, zero heat is generated anywhere (Other than the normal losses because no conductor is perfect at the temp range we live in.)

The pot has to be conductive - like steel, copper, aluminum - for the varying magnetic field to "Induce" an electric current in the pot bottom. That current creates heat in the pot bottom, which cooks the food. IIRC, also, the pots are made of a specially formulated magnetic material to optimize the heat generated in the bottom through induction.

Now then - Before the conductive pot is set atop the hob, the magnetic field kind of bulges up into the air above the hob. Probably a matter of several inches. The frequency of the field is not high enough for much radiation, like from an antenna, so if you do not lie down across the hob, your PM case - which is a conductor - should not have a lot of energy coupled to it. The only way to find out if you are one of the unlucky ones is to try it!

Set the pot atop the hob & the magnetic field gets captured & distorted by the conductive bottom & is pretty much confined to the inside of the bottom of the pot. Especially if the pot is made of steel, a magnetic material.

Bottom line - DON'T turn the hob on till you place the pot atop the hob & turn it off just before you remove the pot.

You cannot pre-heat an inductive hob & the only residual heat is from the hot pot bottom being in intimate contact w/ the hob surface.

These devices are intentionally built so that magnetic energy does NOT escape from the hob-pot combination. If it did escape, it would be inefficient & cost more money to operate. Electric motors & electric power company transformers are designed the same way - to preclude energy loss.

Dunno if you have them in the UK, but here in the US power distribution is becoming commonly underground, with transformer boxes at or near each house in either the front yard (garden) or back yard. The power comes into the transformer at 13,000 volts (Typically) & leaves for the house at 240 Volts. I have been at my transformer box & lain across the top of it w/ my PM right on the steel enclosure. No effect on PM or me. Of course the steel box is a magnetic shield. I have also been standing w/ the power company maintenance guys when they had the box open & were working on it w/ no ill effect.

Induction hobs should be safe - as long as you don't lean over them w/ your PM close to the hob while it is turned ON w/o a pot atop it.

Donr

Thank you

by Angelcat - 2014-05-03 11:05:40

Hello Donr, my husband says that is the best explanation he has read. So, I can still do the cooking and there was me thinking I could hand it over to him!
When a cardiac technician advises not to use induction hobs, you naturally think he knows what he is talking about. Anyway, I am glad I asked the question and hope your answer helps others with the same query.
Many thanks
Di

WOW

by NiceNiecey - 2014-05-03 12:05:16

Man, Ian, way to scare everyone! Ha!

Let me tell you, from what I've read, I would not get near one. I'd never heard of a "hob" until I saw it on this site and I don't plan to ever get one. Who knew? I'm sticking with gas!

Niecey

Great explanation Don but ..

by IAN MC - 2014-05-03 12:05:54

I still don't know why my PM beeps when I approach an induction hob ??????

Ian

The mysterious beeping

by IAN MC - 2014-05-04 08:05:15

Interesting theory, Don, and anything in life is possible !

All I can say is that when I beeped after being in close proximity to a neighbour's induction hob ,the other people who were there stared at me as I rapidly retreated and said " What is that noise ? " . They all thought that I was making the noise, one even asked if it was my mating call.

But few things in life are certain ( apart from Tattoo man ALWAYS being online on this site ) so maybe the hob had ventriloquist skills, and maybe it was all an illusion but I don't think so.

You rightly say that beeping is not mentioned anywhere in the Medtronic Advisa manual, but I bet it's not mentioned in the manual for the hob either.

I have written to Medtronic and am awaiting their reply.

When I start hearing voices I will seek medical advice !

Cheers

Ian

Ian: Don't expect a reply....

by donr - 2014-05-04 10:05:59

....from Medtronic soon! After all, it takes time for a lawyer to write anything!

Don't get me wrong - it was NOT imaginary at all, but very real.

Ever hear a power transformer in the grid serving your house hum w/ a 50 Hz hum? does it all the time. The bigger the transformer, the louder the hum.

Two questions I forgot to ask that would make my answer different:

1) was it a Beep, Beep, Beep, repetitive sound or a continuous Beeeeeeeeep that ended when you moved away?

2) Did the others hear it also? Or, were you the only one who did?

3) Do you, by any chance, wear a hearing aid - or two?

4) Was the Beep extremely high in frequency.

(I know, I can't count!)

I'll have to see if I can find an induction hob here & try it out - I have a Medtronic PM, but it's a Versa model.

Donr

A reply from my EP

by Angelcat - 2014-05-05 01:05:48

He knows of no beeping either and it is fine to carry on cooking with induction. What a shame, I thought I was going to delegate cooking to my husband!
I am happy but I would still like to know why Ian's beeps, I'd send it back, must be faulty (only joking Ian). Hope the puzzle resolves itself soon.
Angel blessings
Di

Ian: I know an answer!!!

by donr - 2014-05-05 01:05:50

I called the Medtronic Mothership in Minneapolis & asked them about beeping PM's.

He said that one or both of us are nuts or needed our hearing checked - none of their models in either the Advisa or Versa types make any audible sounds.

I didn't ask him about PM's & great Whites.

This is getting even more interestinger!

Donr

I wonder what it's worth on E-Bay ?

by IAN MC - 2014-05-05 02:05:48

.. the only beeping Medtronic Advisa ever made ?

I find this extraordinary; I know that I am not crazy ( but I do sometimes worry about all of the others )

Thanks for making the phone call, Don and thanks DI, for starting an interesting thread .

Ian

Don..answers

by IAN MC - 2014-05-05 05:05:04

1) Repetitive beep rather than continuous

2) Yes, the others heard it. They think I am weird !

3 ) No I don't ; my wife thinks I should wear several

4) Highish but not so high that only dogs can hear it

I look forward to the results of your experiment if you can find a friendly neighbour with a hob. What you will do for science eh !

Cheers

Ian

I used the induction hob!

by Angelcat - 2014-05-05 08:05:32

Hi Ian and Donr, well I opened a good discussion on induction and have learned a lot, thank you. I actually used my hob yesterday, made sure the pan covered the whole ring and then turned it on and turned it off before removing pan. No beeps from either my PM or hearing aids!! So I think I am safe, well I hope so.
I look forward to more responses from you both and hope you stay well and happy.
Di

This gets interestinger & interestinger...

by donr - 2014-05-05 09:05:57

....as time goes on. There are few induction hobs in the US. Just never caught on, though they have been marketed.

BTW - we call them "Eyes" or "Burners." Generally speaking, if it's electric, it's an eye; if gas, it's a burner. Not unusual for people to use the terms interchangebly, however. Can any of you give me an explanation for where the term "Hob" originates? A lot of variable terms between American & UK English have some immediately obvious explanation, but this one evades me.

Angel, we are of the same cohort - 1936. I also host a pair of hearing aids. Mine do strange things at times - mainly beep at me because they eat batteries. I would not be surprised if they beeped when leaning over an induction hob. They are digital & have 5 different programs in them for signal processing - I only take advantage of one of them, however.

One interesting fact I read while researching this was that the hob the geek EE discombobulated (A technical term meaning "Took it all apart w/ very little hope of ever getting it back together & working again.") has a sensor circuit in t=it that detected whether or not you had a pot or pan atop the device. No pot - would not turn on till you placed on on it. Nifty, eh?

I'm going to call Medtronic today & ask them at their world HQ about beeping PM's. I've already called them & asked if the PM emits enough EMI to attract pelagic sharks (Like the Great White, for those in the land of Oz - we have 'em too.) They are used to crazy questions.

Donr

How long can we keep this up, do you think?

by Angelcat - 2014-05-05 10:05:56

In the UK induction does not seem to have caught on. We researched getting a new hob when I got fed up cleaning a gas one and my hands are not all that good. So we got a Die Dietrich one from Germany 7 years ago as we could not find any here. I think they are very economical and soooo easy to clean!
How come you have five settings on your hearing aids? I only have three! Mind you, we are talking NHS but I was one of the first in Cornwall to have digital ones and had to write a report on what I thought of them. My batteries last about 2 weeks on average.
Can't wait to see what the answer will be from Medtronic!
1936 was a very good year!
Take care
Di

Angel, Ian, et al...

by donr - 2014-05-06 01:05:47

I have established communications w/ a pair of evil geniuses - one of whom is a certain Prof Moriarty of London.

They have found your conundrum very interesting & will ponder it deeply. Perhaps even coming up w/ some explanation that makes sense.

Donr

Angelcat............

by Tattoo Man - 2014-05-06 06:05:08


.....................on the subject of Induction Hobs, or Cookplates as they are known as in the US. They have been available in the UK from as early as 1972.For many years these were astronomically expensive items from manufacturers such as Westinghouse.

Now being in the kitchen/interiors business myself, these were outside the budgets for all but the uber-rich...I recall prices of £700 back in the '70's.

Induction sales are now up year-on-year and a discussion I had only a few weeks ago with a prominent UK distributor confirms that within the next ten years they will form the bulk of electric cooking. Price and lack of knowledge has always been a problem...added to by the need to buy special pans (in some cases).

Gas-type speed and safety (cold when switched off) are major advantages for the 'serious cook' or , for instance, the Elderly/infirm.

DON.....................

The origin of the word 'Hob' are 17th century and is defined as;

"A flat metal shelf at the back or side of a fireplace level with the grate top, used for heating pans"


IAN MC..........................

I don't know why Blake chooses to keep me out at the front of the classroom as he does. Is it because I have been so often on the brink of expulsion that he likes to keep an eye on me ??

Best wishes to all at PMC and thanks for this very interesting thread.

I hope that like 'Bono' from U2 you, someday " Find what you're looking for"

Tattoo Man

Watch Out

by BanjoPacer - 2014-05-06 06:05:20

INduction units are producing magnetic fields that are capable of causing metal to heat, this is due to the field that the induction coil is making causes the molcules to move faster and causing heat, many heat treat methods are done by induction, heating up the metal and then quenching it in oil causes the metal to increase in hardness or rockwell.
Ok with that said, some induction units are strong enough to cause your pacemake to do funny things, even though the body of the pacemaker is stainless steel which isn't bothered by the induction field the electronics inside the PM can be effected. I worked at a plant that made auto parts and we had induction hardening units, I was working on one and I had a wrench in my pocket and I was standing in front of the unit while it was running and the wrench started getting warm in my pocket, So I believe that if I had a PM at that time I would have felt sideffects from the machine. Now of course the machine was very high powered, and it's not what most people will ever see, but it is something that could effect your PM.

Serious cook I am not .......

by Angelcat - 2014-05-06 06:05:54

But I am old and infirm!! Don't like the word "elderly"!!!
Thanks for that Tattoo Man.
A very interesting comment about the cost of induction Cookplates (hobs!) because we paid about £400 just over 7 years ago. Personally I think they are worth every penny!
This has been a very enlightening thread and an enjoyable read, thanks to all of you.
Stay well with a calm heart. Angel blessings
Di

ANother 30 plus years.....

by donr - 2014-05-06 07:05:37

.....& I can die happy - I'll know where "Hob" came from.

TM: Thank you for that. It has piqued my curiosity ever since I first heard the term when we moved to London back in 1979 for a short stint.

OTOH, I have never heard a hob called a "Cookplate" in the US. Could be a very regional thing - like in Boston in Massachussets, where there are some unusual terms used & not heard in other places. We have a significant number of those sorts of things occurring.

Speaking of language - did y'all know that the Red shaped "Stop" sign is pretty much internationally universal? In 1992 I was out in very rural Russia, about 80 miles from Moscow & we came to an intersection & there was a big, red, octagonal STOP sign - in English, no less - in an area that was previously off limits to foreigners. I was so surprised that I took a photo of it to add to my collection of trivially useless photos.

Have a good day - whatever is left of it.

Donr

Hob is a very old description

by SaraTB - 2014-05-06 08:05:30

In the UK, we use "hob" to describe either what's known in the US as a cooktop, or simply to refer to the burner rings on the top of a stove (which the US would call a range).

It's a very old description, and originates in the 16thC if not earlier, and referred to a metal plate at the side of the fire, where a kettle or pot could heat.

Incidentally, induction is becoming increasingly popular in the US, according to the posts I read at a kitchen renovation website: popular with folk who want high-powered burners, but don't want or don't have a connection to gas. (In the NorthEast, most gas is by propane tanks - no mains gas connections).

I used an induction hob in the UK in a summer rental a few years back and, despite being 100% paced, had no problems at all. I'm fascinated at the idea of Ian beeping away in his friend's kitchen!

If people think.....

by donr - 2014-05-07 07:05:46

.....that Ian beeping away is something to behold, wait till you see him standing there blinking away like a neon sign advertizing some brand of ale!

That will only happen if we take him into the Range Rover manufacturing plant and he stands too close to the induction furnace where they are heat treating rear axles. That device heats a chunk of steel to over 900 degrees F - cherry red in color - in about 30 seconds. A true sight to behold!

Better than last year's Christmas tree!

Donr

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