EMF concerns and protection

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Rock86

Senior Member
Location
new york
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Electrical Engineer / Electrician
I'm working on a project that makes feel like I should go back to school and relearn about EMF.

We have a client that is very concerned about EMF. So much so that we had a very long discussion on where to place a sub-panel in a dorm type living unit. The concern was that it would radiate EMF through the wall and affect a person sitting on a toilet.

Has anyone done research on EMF within dwelling units? Has anyone installed any of the shielding materials that are on the market? Has anyone experienced a difference when not in the presence of significant EMF radiation?

Does anyone have any good educational information on the subject?
 
Search this forum for "Karl Riley".

He has done considerable research on the subject, wrote a book, and is probably reasonably balanced on practical solutions rather than snake oil.

His main contention is that strongest EMI issues are caused by bad wiring, and that if you use code correct approaches you will mitigate most issues.

This is a field chock full of suggestion/placebo/nocebo effects. The jury is still out on weather there are real effects, and if there are real effects they are small/non-existent for most people.

Lots of snake oil salesmen preying on fear, selling products that have no discernible effects.

My personal hunch: there are subtle effects which are not inherently harmful but which may be percieved, and the perception is potentially irritating and thus indirectly harmful.

The analogy that I use is a neighbor quietly playing music that you _hate_. The music is so quiet that you can't hear it over the normal noise of the day. But in the middle of the night when everything else is quiet, you can just make out the rhythm you despise. Just loud enough to annoy you, but so quiet you can't really do anything about it.

Jon
 
winnie said:
Search this forum for "Karl Riley".

He has done considerable research on the subject, wrote a book, and is probably reasonably balanced on practical solutions rather than snake oil.

His main contention is that strongest EMI issues are caused by bad wiring, and that if you use code correct approaches you will mitigate most issues.

This is a field chock full of suggestion/placebo/nocebo effects. The jury is still out on weather there are real effects, and if there are real effects they are small/non-existent for most people.

Lots of snake oil salesmen preying on fear, selling products that have no discernible effects.

My personal hunch: there are subtle effects which are not inherently harmful but which may be percieved, and the perception is potentially irritating and thus indirectly harmful.

The analogy that I use is a neighbor quietly playing music that you _hate_. The music is so quiet that you can't hear it over the normal noise of the day. But in the middle of the night when everything else is quiet, you can just make out the rhythm you despise. Just loud enough to annoy you, but so quiet you can't really do anything about it.

Jon
Click to expand...
That's a great analogy. Thanks.
 
Keep in mind that the analogy is for my hunch about what is going on. I don't think that anything has been proven. It is a pure speculation based on interacting with a friend who claimed electromagnetic sensitivity, reading about proposed mechanisms, and observations of suggestibility in people who claim electromagnetic sensitivity.

To describe my hunch another way: My hunch is that some people can perceive EMI in some fashion, but that it doesn't rise to the level of a conscious awareness. They are then harmed by that perception in the same way that you might be harmed by barely perceptible annoying sounds.
 
It's not particularly plausible that anything would be felt sitting near a subpanel that wouldn't be felt in the presence of the load itself. The field at the subpanel is only the sum of the fields at the loads, and is likely to be dominated by the largest load. In other words, there is no very sensible reason to be that much more worried about a subpanel than about whatever they are using electricity for in the first place.

A key point is that where you have wires in the same circuit bundled together, and the currents remain equal, the magnetic fields from the wires cancel each other out. This is a key part of why the code requires conductors of the same circuit to be in the same cable or conduit. As long as things are wired code compliantly in this manner, with all current returning from a load in the same cable or conduit, I'm personally skeptical that there is any magnetic field outside that cable or conduit that a human can perceive at typical building voltages. Mind you, there is plenty of wiring out there that either by error or by age (knob and tube) doesn't meet this standard, so this doesn't rule out that some people might be perceiving magnetic fields from bad or old electrical wiring in buildings. Although I'm still fairly skeptical in general that they really do.
 
OK, so here is the deal:
If all the Hot & Neutral current is traveling in the same cable or conduit. Then about 99% of their fields cancel within about 2 inches of the cable or conduit. More cancellation if the conduit is metal. But with some strange wiring practices or with 'lost neutral' currents, all bets are off. I have read about several amps traveling thru water pipes.
I have read about medical tests when patients could not tell if there was an electrical field or not.
Note that some EMF marketers use an extremely sensitive meter to measure very small fields. And use that irrelevant reading to scare their customers.
 
winnie said:
Keep in mind that the analogy is for my hunch about what is going on. I don't think that anything has been proven. It is a pure speculation based on interacting with a friend who claimed electromagnetic sensitivity, reading about proposed mechanisms, and observations of suggestibility in people who claim electromagnetic sensitivity.

To describe my hunch another way: My hunch is that some people can perceive EMI in some fashion, but that it doesn't rise to the level of a conscious awareness. They are then harmed by that perception in the same way that you might be harmed by barely perceptible annoying sounds.
Click to expand...
Yes. I agree. Example, water witching is similar, there are some who have better perception ( this has been proven) and that tend to become more “magic”. The information from Mr Riley is excellent. He has a video on emf research in CA schools which clearly shows electrical wiring mistakes are the cause of emfs
 
Speedskater said:
OK, so here is the deal:
If all the Hot & Neutral current is traveling in the same cable or conduit. Then about 99% of their fields cancel within about 2 inches of the cable or conduit. More cancellation if the conduit is metal. But with some strange wiring practices or with 'lost neutral' currents, all bets are off. I have read about several amps traveling thru water pipes.
Click to expand...

Small correction:

If hot and neutral current is balanced in the same cable or conduit, the _magnetic_ field cancels quite quickly (my guess is < 2"). However the _electric_ field will extend a greater distance because it is _not_ balanced for an ordinary 120V branch circuit.

A metal wiring method (conduit or MC) where the conductors are surrounded by a grounded conductive 'shield' will effectively kill the _electric_ field, but will do little for magnetic fields caused by unbalanced current.

-Jon
 
Rock86 said:
We have a client that is very concerned about EMF. So much so that we had a very long discussion on where to place a sub-panel in a dorm type living unit. The concern was that it would radiate EMF through the wall and affect a person sitting on a toilet.
Click to expand...
Let me guess, A vegan, who can't tolerate gluten, and drinks soy lattes who will lecture you about health issues between bong hits.
 
winnie said:
The analogy that I use is a neighbor quietly playing music that you _hate_. The music is so quiet that you can't hear it over the normal noise of the day. But in the middle of the night when everything else is quiet, you can just make out the rhythm you despise. Just loud enough to annoy you, but so quiet you can't really do anything about it.
Click to expand...
I would imagine what you're trying to do at the time (say, working vs sleeping) plays a part in that.
 
I worked on a house for an owner worried about EMF. Just the fact that I was willing to listen and give some basic answers (properly wired circuits cancel magnetic fields, energy dissipates at the square of the distance,...) made for a good working relationship. We used metal conduit and MC cable for the branch circuits and put in a couple of contactors that would kill all the power to the master bedroom. It didn't really matter to me if any of the owner's concerns were real or imagined, it's your house I'll wire it any way you want it was my attitude.
 
I have worked in quite a few homes that had large electromagnetic field readings. In every one I was able to fix the wiring problem that caused the issue.

There are all things on the market that I can't imagine are helpful. I do believe that some people can sense electromagnetic field's but I also think that most of them are sad and depressed and are looking for some cause of their unhappiness.

I was working at a customers house trying to find where the wiring issues were that were causing the electromagnetic field's. The customer's mother was there and she whisper to me that she thought her daughter was crazier than her son and that her son believes he is an alien.

Here are a few wiring things that can cause electromagnetic field's. In my case the problem was always one of these below.

1. If the EGC is touching the grounded conductor after the OCPD.

2. If the grounded conductor from two different circuits are connected together after the Ocpd. I see this in 2 or 3 gang switches where either the neutrals get crossed or they are all tied together. This issue will come to light where afci's are concerned.

3. If the circuit conductor are not run together as in K&T wiring or sometimes you see this in 3 way switches where the EC runs 2 wire cable between the 3 ways and picks up a neutral at one box and the feed at the other.
 
Lawyers have tried for 45 years to wring any $$ they could from pocos based on 'harm' to schoolchildren near power lines.

There have been no peer reviewed studies showing 60 Hz electric or magnetic field health issues.
There have been studies showing cows milk production can be reduced due to ground currents and hoof to hoof stray ground currents.

I was part of a 1980s lawsuit claiming testing of EMP causing leukemia (10s of thousands of volts/meter field up into the megaHz), no causal relationships demonstrated (settled out of court),

Got a chuckle out of Joe's vegan complaining about EF between bong hits. :oops:

All that said makes no difference to the OP client, where there is a perceived problem. Rock86 best handle the situation like ActionDave summarized. Heck, if you can do some add on billable work, why not, putting it all in conduit should be a good selling point to the paranoid client?
 
I don't buy the tin foil hat approach to this junk science nonsense but to each his own. I worked in an apartment building where they spent hundreds of thousands of dollars on 1/4" aluminum plate shielding because someone told them that the "readings are high".


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