EMI from electric shavers etc

[Martin KyteParticipant @martinkyte99762]

Posted by pgk pgk on 25/03/2020 07:26:17:

Posted by Martin Kyte on 24/03/2020 22:31:30:

Can anyone remember what desperate Dan used for shaving?

I know it was something wierd but cannot remember what.

Blowlamp comes to mind and once shooting beard hairs off with a pistol??

pgk

That was it. Ha Ha

regards Martin

[Roger HartParticipant @rogerhart88496]

Long ago a colleague was sent to a small island in a big ocean a long way from anywhere. His job, to solder the seams on copper sheets glued to the inside walls of a room. The room was to hold teleprinters, code machines and computers. Officer in charge declared that when the last seam was soldered the radio in the middle of the room would stop playing – it didn't All to do with near fields and far fields and sensitivity to the magnetic and electric component of radio waves.

As with others I doubt a bit of al foil will make much difference. Complicated business screening and EMI. Personally I would not worry about a shaver but I would not be waving it over my ticker either.

[Robert Atkinson 2Participant @robertatkinson2]

Posted by not done it yet on 25/03/2020 09:47:10:

I suspect this is an entirely over-hyped thread. Thousands of people with pacemakers get by living fairly normal lives.

When I worked in the precious metals industry, we were simply advised to keep away from induction furnaces and the like. Electric shavers are at the far end of the spectrum. Microwaves , ANY electric motor, VFDs, ultrasonic welders or cleaners, etc are far more likely to interfere, I would have thought.

NDIY,

This is not a helpful post. You obviousy have no training or expertise in EMI/EMC. Things are constantly changing in both the EMI/EMC and Medical device worlds. The OP should follow the guidance given by the device manufacturer and / or medical professionals.
No one on this forum has enough information to suggest anything else. We do not even know the type of medical device involved.
You seem to have the view on this and other threads that "I/we/they/ have done it for ages without any problem so don't worry about it" for safety and compliance issues. This approach is irresponsible at best.

 

Robrt G8RPI.

Edited By Robert Atkinson 2 on 25/03/2020 12:31:25

[Howard LewisParticipant @howardlewis46836]

I am sure that Robert will confirm, rotary shavers (Phillishaves etc )are likely to be driven by a rotating electric motor, and the reciprocating types (Braun etc ) have an armature which oscillates inside a static (as in stationary ) coil.

The rotary types, if brushed motors, are likely to be universal capable of operating off AC or DC.

The reciprocating types will only operate off AC current, since they rely on the electromagnetic field rising and falling because of the Alternating Current, to attract the armature (carrying the shaver cutter ) within the coils.

The armature will oscillate within the solenoid, against springs.

Both are likely to have small electromagnetic fields around them (probably very small considering the current that they draw.

If operating from a shaver socket, as a safety precaution, the voltage will be half mains voltage about a centre point which is at earth potential.

A small electromagnet field could be classed as EMI, but is likely to be very small, in my relatively unqualified view.

Woulds any experts wish to discuss the level the level of this field, and speculate upon the danger to the OP?

Howard

Must be a record for typos!

Edited By Howard Lewis on 25/03/2020 15:17:40

[Robert Atkinson 2Participant @robertatkinson2]

Very few modern shavers use the resonant armature type mechanism Howard describes. All of the Braun shavers I have had for at least 20 years have had a brushed DC motor. Larger mains powered hair clippers still tend to use a resonant armature though.

I will say agin NO ONE ON THIS FORUM HAS ENOUGH INFORMATION (based on what has been posted so far) to make any reasonable judgement about the OP's safety when using an electric razor.

Robert G8RPI CEng FRAeS

[SillyOldDufferModerator @sillyoldduffer]

Posted by Howard Lewis on 25/03/2020 15:16:16:

…

A small electromagnet field could be classed as EMI, but is likely to be very small, in my relatively unqualified view.

Woulds any experts wish to discuss the level the level of this field, and speculate upon the danger to the OP?

…

Proximity to the field is also a major factor. With a mains powered shaver it's likely that the cable will drape up close and personal across the user's chest, multiplying the risk. Radiation off the wire is dangerous too.

I'm always surprised the forum expects there to be a single simple answer to questions like this. There are many makes, models, and variants of pacemaker. They've been made at different times and to different standards. Probably thousands of different Electric razors out there. No-one knows how compatible a specific pacemaker and razor are unless they've been tested.

The only source I would trust on the subject is the manufacturer of the implant. Whilst I doubt an electric razor is very dangerous, I personally wouldn't take the risk of operating a suspect EMI source next to the sensitive electronics keeping my dodgy ticker going.

Accidental ignorance is a menace too. After his 999 collapse a relative told me he'd been fitted with a pacemaker and this was confirmed by his wife. Both wrong, it was a defibrillator. In the excitement and stress, neither of them had taken in what the doctor said. Less creditably, it was a couple of months before they read the leaflets and longer before they twigged a defibrillator isn't a pacemaker. Probably not a good idea for people like them to take safety advice off the internet!

Dave

[Brian MorehenParticipant @brianmorehen85290]

Most electric shavers used to have inferance supressors fitted sounds like these have decided not to work

Years since i last took one to pieces to repair dont even know if these are still fitted most shavers are now rechargable .

Brian M

[Enough!Participant @enough]

Sam, your ICD/pacemaker Clinic should be able interrogate the device and see if it's been picking up significant interference and possibly even the timing of it. If they deem the interference is not an actual problem for the device in your case, they can turn down the sensitivity a notch.

That happened to me when using (wireless) headphones to watch TV. My hearing issues are such that I would deafen my wife if I watch normally with volume where I needed it. Once we determined what it was they turned the sensitivity down a little and it never shows up now.

Other than that, when i first got my ICD (2009), I was pretty nervous about this stuff. You learn to live with it and exercise due cation and it becomes part of life. I know I can never do (or be around) electric welding. I was nervous about larger motors (say 1HP and up) but none of mine are like that and don't seem to have been a problem. Ditto my VFD.

As Michael says, the limitations are real (if sometimes vague/exaggerated by manufacturers protecting their legal positions) but common sense does wonders. Millions live with these without problems. (Most were probably as nervous as you and I at first)

[Neil WyattModerator @neilwyatt]

Hi Sam,

Perhaps you shoudl co0nsider giving up shaving your chest?

You are getting a bit old to be a Chippendale…

Neil

[Neil WyattModerator @neilwyatt]

More seriously, NHS says keep a shaver witha mains cord 6 inches away from eth pacemaker (I assume that includes the cord).

Lots of advice here. Watch out for that CB base station (10 feet!)

http://www.wwl.nhs.uk/Specialities/Cardiology/pacemaker_faq.aspx

Neil

[not done it yetParticipant @notdoneityet]

I agree with most comments, to a degree. Mother in law had a Pacemaker for years and she did not have any bother with interference. I would strongly suggest the OP searches out information from the suppliers of these devices, not make threads on a model engineering forum if he wants medical advice. I strongly suspect that these devices are designed to be fairly resistant to interference.

Simple solution is to buy a battery operated shaver and avoid any possible problem entirely, avoid having to run it inside a biscuit tin or anything else. Magnetic fields are more important – like airport security metal detectors, electric hobs, large speakers, etc. I would expect an electric shaver to be safe if kept more than 150mm from the pacemaker. The advice on the net seems to be ‘if You get palpitations, move further away’.

Get real, keep it simple. Pacemakers are in use for thousands of people most of them getting on with life fairly normally. Read this maybe?

**LINK**

and not get hooked up with worry about an electric shaver.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 25/03/2020 15:16:16:

[…]

A small electromagnet field could be classed as EMI, but is likely to be very small, in my relatively unqualified view.

Woulds any experts wish to discuss the level the level of this field, and speculate upon the danger to the OP?

Howard

.

Boston Scientific offers the nearest I have found to an accessible expert opinion

I have already linked their document and quoted the relevant line.

I am not an expert in Electromagnetic Interference, but I do have a personal interest in pacemakers.

MichaelG.

[Robert Atkinson 2Participant @robertatkinson2]

NDIY,

Why do you persist with these dangerous comments like " Simple solution is to buy a battery operated shaver and avoid any possible problem entirely, … " What basis do you have for thinking battery shaver has less intererence than a mains one?
I've been a EMI/EMC specialist for many years (my first formal training in the subject was in 1978) even I can't tell which is better or worse because there are to many variables, e.g. motor type, does it have electronics? ete. etc.

Why do people assue the OP has a ICD or pacemaker? There are many different implantable devices these days and while I've assumed the OP is having an implantable device, he has not actually told us what exactl is being one.

Neil,
I think this thread should be closed.

Robert G8RPI.

[Sam StonesParticipant @samstones42903]

With apologies to everyone, I think Robert is correct Neil.

Close the thread.

If anyone wants any further information from me, I'd be happy to go via the message board, even direct email.

Best wishes to all, and keep safe.

Not so Desperate Sam

[Martin KyteParticipant @martinkyte99762]

To be fair the original question was is it a good idea to wrap the shaver in foil and cling film and the consensus was no. Which is a safe response. With respect to Roberts question as to " What basis do you have for thinking battery shaver has less intererence than a mains one? for a start the battery model is a self contained unit and will have complience to some standard that can be ascertained. You can at least get some information from the manufacturer. With a mains system the shaver lead will radiate as will the wall wiring and transformer none of which can be tied down without actually making field measurement which is impractical and in that I would agree with Robert that one cannot really comment. Suggesting that a self contained shaver is purchased is a reasonable direction to move in. Devices do comply with EMI rules and that can be ascertained as I say. If this is a pacemaker issue one can then say to the implant team I have a bla bla shaver to whatever standard, am I safe.

I draw attention to Michael Gilligan's Link and post saying avoid draping the cord over the implant. Batter shavers remove that possibility at least.

Overall Sam asked us. He knows that we think reasonably about things but in the main are not specialists and has probably received some sound advice including ask the implant team which I think is fair enough.

regards Martin

[Michael GilliganParticipant @michaelgilligan61133]

Before the thread gets locked … and for no particular reason except that I am VERY pleased to have it :

Here is my pacemaker

.

.

It’s a 3-wire device, from St Jude, and does Cardiac Resynchronisation Therapy.

A big Thank You to the NHS in general, and Wythenshawe Hospital in particular

MichaelG.

[Martin KyteParticipant @martinkyte99762]

Thats a bit of a messy installation, not a single cable clip ;O)

Keep with the beat Michael.

regards Martin

[Michael GilliganParticipant @michaelgilligan61133]

[Robert Atkinson 2Participant @robertatkinson2]

Both mains and battery shavers have to meet the same EMI/EMC emissions levels. This includes emissions from leads.
The advice to keep electrical / electronic items away from implanted devices will be predicated on those items meeting the mandated emissions level.

Robert G8RPI

[Enough!Participant @enough]

Posted by Michael Gilligan on 25/03/2020 21:54:16:

Before the thread gets locked …

It’s a 3-wire device, from St Jude, and does Cardiac Resynchronisation Therapy.

That's where, if the heart is running too fast (arrhythmia etc) they speed it up to slow it down? Mine does that – though I never notice. They do test it at the pacemaker clinic and tell me its about to happen and i can feel it (just barely) then.

It's the thought of the big one (defib) that scares the bejeepers out of me.

[ I really can't see why the thread needs to be locked. Do we really all need protection from ourselves just because someone might (a very big might, in my opinion) be foolish enough act on medical advice he received in the Model Engineer Forums without checking a truly medical opinion first? ]

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bandersnatch on 26/03/2020 00:43:39:

Posted by Michael Gilligan on 25/03/2020 21:54:16:

Before the thread gets locked …

It’s a 3-wire device, from St Jude, and does Cardiac Resynchronisation Therapy.

That's where, if the heart is running too fast (arrhythmia etc) they speed it up to slow it down?

[…]

It's the thought of the big one (defib) that scares the bejeepers out of me.

 

.

No … CRT is a little different

I will post something more about it later, if the thread is still open.

MichaelG.

.

P.S. … We discussed the ‘defib’ option in some detail … and I declined

Edited By Michael Gilligan on 26/03/2020 06:49:11

[Brian GParticipant @briang]

Is this the best place to find this information Sam? My guess (and it is just a guess) is that there will be more variation in the sensitivity of different types of medical device than different brands of shaver. Perhaps the device (medical, not shaver) manufacturer, the hospital that carried out the procedure or the British Heart Foundation (who have a leaflet which includes recommended separation from different electrical devices) may be much better placed to advise you.

Brian G

[Michael GilliganParticipant @michaelgilligan61133]

As promised: Here is a little more about my CRT

In early 2016, it was known that I had a ‘Left Bundle Branch Block’ … but this was considered fairly benign, and it was more important to fix the plumbing [quadruple Coronary Artery Bypass Grafts]

In late 2016 the electrical problems became significant, and they fitted a conventional 2-wire pacemaker.

In 2018, I suffered ‘Severe Heart Failure’ [the ‘volume fraction’ of pumping should be about 70%, mine had suddenly dropped to 17%] … Fortunately, fitting a 3-wire CRT device; re-using the original two, and adding the tricky third wire, worked very nicely. The basic problem was failure of the heart’s electrical system, which was causing the left and right ventricles to pump in anti-phase … so the blood was just washing between the chambers !

MichaelG.

.

This page features a brilliant animation showing the problem:

https://watchlearnlive.heart.org/CVML_Mobile.php?moduleSelect=cardrt

Yes, it does refer to arrhythmia … but my device is active on over 90% of my heartbeats, so it’s really doing most of the synchronisation work.

… and

Here’s a short snippet from one of Tom Kenny’s excellent books:

Ref: 

The Nuts and Bolts of Cardiac Resynchronization Therapy

 

Tom Kenny

 

Vice President Clinical Education & Training

 

St Jude Medical, Austin, Texas

.

 

See also: 

The Nuts & Bolts of Cardiac Pacing

 

Edited By Michael Gilligan on 26/03/2020 09:12:47

[Mike PooleParticipant @mikepoole82104]

Many years ago I was given a pacemaker as a curio, it was recovered in a routine exchange, a scope showed it was still ticking away for many years after the exchange. My mother recently had a pacemaker fitted and I accompanied her to her first checkup, it appears they are very sophisticated devices now, they are interrogated with a wireless connection and seem to transmit a log and live data, clever stuff.

Mike

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 26/03/2020 06:48:48:

.

No … CRT is a little different

.

Apologies, Bandersnatch … I’ve just noticed that ^^^ seems rather abrupt

What I meant to write was more like:

No … my CRT is a little different

MichaelG.

[Author]

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