Specific EMI numbers

Has anyone actually received from device manufacturer the actual upper limit of EMF that you need to avoid. All of the documents I can find say that you are "Probably" or "Should" be ok within some proximity of the machinery. That is really not good enough for me. I work for a university in maintenance and have the opportunity to come near all sorts of circuits and equipment that may otherwise not be good for me to be around. I have called my manufacturer and researched online for the data but can find nothing specific. Has anyone ever gotten that type of data?

3 Comments

The only thing I've been able to find

by Theknotguy - 2016-02-24 09:02:59

The only thing I've been able to find is a report put out by the University of Michigan that said they were able to cause EMI interference with an EXTERNAL pacemaker when the EMI source was within 10 feet of the pacemaker. The same test said they had to be within 2 inches of an INTERNAL pacemaker.

The report didn't give what kind of EMI, how strong, or for how long, nor did it give brands, makes, and models of pacemakers. The test was conducted (supposedly) over ten years ago. Right at the moment I'm not sure if I can find where and when the report was generated.

Based upon the above information I'm very skeptical when someone says they are affected by EMI. I haven't run into any situations where my pacemaker has been affected by EMI and that's after knowingly going into EMI fields that will cause video jitter on the old tube style of monitors.

The reason I know about the EMI field was because we did run into a situation where the EMF field was causing video jitter on the old style tube monitors. We actually put the monitor on a cart and moved it around while watching for video jitter. This particular field was about eight feet long by four feet high. It was being generated at the location where the main power was being brought into a building. I didn't have any better equipment for testing other than the monitor and watching the video jitter. We ended up moving people out of the area and making it into a storage area.

On this site I've had some people get very upset when I've questioned their comments. One person says they can feel WiFi which is very hard for me to believe. Another has said their pacemaker sets off the store security at a specific store. The only question in my mind is how they know for sure it's the pacemaker that sets off the alarm. Is it the belt buckle their wearing? Is it the keys they're carrying? Is it something else? Also, just because the pacemaker may set off the alarm it still doesn't mean the pacemaker is being affected. It just means the store security alarm may be set off by the pacemaker.

Medtronic says to stay away from running electric motors. Minimum distance given is 6 - 12 inches. But I put up a post where I drilled about a hundred holes with a larger DeWalt drill. I had forgotten all about my pacemaker and was leaning on the drill while it was running. My pacemaker was pushing up against the drill handle. So I was well within the 6-12 inches. No problems.

So, to answer your question, I've never been able to find any specific information. I'd like to get some good concrete information if you find it. Mostly what we see on this site is anecdotal information and bad information that has just been repeated over and over.

Personally I haven't experienced any problems with RF or EMI and I feel you won't either. The first time I walked into a known EMI source was pretty scary, but nothing happened. So I don't worry about it any more. Over Christmas I was at a mall where the store security was set off repeatedly by people looking at items. I specifically walked through the security to see if it would be set off by me and what I was carrying. Nothing happened.

Like I said, if you can find anything I'd really like to know about it.

Another variable ??

by IAN MC - 2016-02-25 01:02:23

As well as all of the variables which Bill mentions it does seem that some people are more sensitive to the effects of electromagnetic fields than others.

Studies are ongoing and the World Health Organisation has even held workshops on the subject. One theory is that varying levels of heavy metals in the human body may affect the way individuals respond to external electro -magnetic fields. It is now increasingly being accepted that electromagnetic hypersensitivity may be a genuine medical condition.

There are many doubters and the jury is still out on the subject but for individuals who do suffer ( or believe they suffer ) then it is a very real problem.

Ian

Old Thread

by BillH - 2016-02-25 12:02:53

Look at this old thread and the link to the study that it has.

http://www.pacemakerclub.com/public/jpage/1/p/story/a/storypage/sid/36018/content.do

But to answer your question there are way to many variable in terms of pacemaker design, lead type, lead length, lead location, PM location to give absolute answers. And on top of that there are lots of variables in the in terms of the heart condition(s) and PM settings.

I just did a calculation and found out that there are 9,542,137 different combinations. And that is just for one model of PM.

And even if you had that information for all 9,542,137 combinations most people don't have the ability to measure the EMI levels.

Then you look at the potentially interfering device. Again you have such a large combination.

For example a piece of equipment that you might be familiar with, a table saw.

Is that 2 hp cabinet saw on 120, a 3 hp cabinet saw on 240, a 5 hp cabinet saw on 240, a larger 12" cabinet saw on 480 volt? Also it could be 1.5 hp contractors table saw. All of those have cast iron tops which will shield some of the EMI.

Or maybe a portable tables saw with a universal motor with stamped steel case or even the newer one which are mostly reinforced plastic?


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