Emf

Status
Not open for further replies.

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
The surgicle staples are most likely titanium. This is because titanium tends to be a bit easier on the immune system, and, titanium is of course nonferrousmagnetic, so if the patient needs an MRI while stapled, there will be less interference. I know this because my stomach is laden with staples, which I assumed where stainless steel, they certainly appear to be stainless steel.
Do you sense it in your staples when your neighbors are downloading data?
 

stevero

Member
Electric vs. Magnetic Fields

Electric vs. Magnetic Fields

Just a couple observations: EMF means "electric AND magnetic fields" when talking about 60 hz. The electric fields are proportional to the voltage of a circuit; the magnetic fields are proportional to the current flowing through a circuit. No current, no magnetic field - but the electric field is still there until the circuit is de-energized.

Her problem, if from 60 hz, is probably the electric field. A gauss meter won't tell you anything about the electric field. You need an e-field meter which is harder to come by and very expensive. Your local utility may have one and may take measurements in the house for you/her. Another approach to sense (but not measure) the e-field would be to get a non-contact voltage probe - the kind that can be adjusted for sensitivity - and dial the sensitivity all the way up. You can walk around the house and look for e-field hot spots. (I consulted on a job where a new house was built right up to a 161-kV transmission line. The voltage probe signaled all through the house.)

You who say the wavelength of 60 hz is thousands of miles are right. BUT linemen who work on energized extra high voltage power lines (345-kV and above) have to watch what they wear. Nylon stitching will send them jumping. Some wear faraday suits. Point is, even though wavelength is thousands of miles, 60 hz electric fields can still bug you.

Of course the electric fields due to household wiring and appliances are minuscule compared to EHV lines at the conductors. Also, the e-fields in her house could be predominately from the power line outside her house. (Is she fed by an overhead or underground line? How close?) Something to consider.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Stevero, I beg to differ with you. EMF can , of course, mean a few different things. It usually means elctromotive force or electromagnetic field. Not Electric and Magnetic Field as you say. A gaussmeter will read emf's just fine.
 

rattus

Senior Member
First time caller today says ever since she had about 100 stainless steel staples in her stomache from an operation, that she is very sensitve to EMF. She claims she cannot even sleep at night without turning ALL the breakers off in the entire house. She says the smart meter on her house puts off such a field that she can't go near it. She says that with all breakers off, she was managing to sleep ok, then her neighbor got a wireless router and is really messing her up. She supposedly can tell when her neighbor is moving data!! Could this woman be off her rocker? The problem is so bad, she wants it corrected immediately or she is moving. I told her that she is feeling something that does not affect 99.9% of people in America. HAs anyone dealt with this?

In my youth I repaired typewriters. One woman claimed that the electricity in her body triggered the keys and caused her to make errors. Of course, the only thing electric about the machine was the motor!
 

stevero

Member
You're wrong

You're wrong

Stevero, I beg to differ with you. EMF can , of course, mean a few different things. It usually means elctromotive force or electromagnetic field. Not Electric and Magnetic Field as you say. A gaussmeter will read emf's just fine.

You're right for communications frequencies, but you're wrong for power frequencies - the electric and magnetic fields are distinctly different.

From IEEE Standard 539 - IEEE Standard Definitions of Terms related to Corona and Field Effects of Overhead Power Lines:

6.1 electromagnetic field: A time-varying field, associated with the electric or magnetic forces and described by Maxwell?s equations. NOTE?The term electromagnetic field is sometimes used to refer to power-frequency electric and magnetic fields, fields that for most practical applications can be considered independent and for which the effects of one component may dominate or be of primary interest. For such situations, the use of the term electric field or magnetic field, as the case may apply, is encouraged.

6.3 electric field strength (E): At a given point in space, the ratio of force on a positive test charge placed at the point to the magnitude of the test charge, in the limit that the magnitude of the test charge goes to zero. The electric field strength at a point in space in an electric field is a vector defined by its space components along three orthogonal axes.
NOTE 1?In a zero magnetic field, the force F is given by F = qE. The magnitudes of the electric field strength components are expressed in volts per meter (V/m), which dimensionally is the same as Newton/Coulomb.
NOTE 2?This term has sometimes been called the electric field intensity, but such use of the word intensity is deprecated in favor of strength, since intensity connotes power in optics and radiation.
NOTE 3?Though they are used often, the use of electric field or E-field is deprecated in favor of electric field strength.

6.5 magnetic field: A vector field of magnetic field strength, H, or of magnetic flux density, B.
NOTE 1?The term is also used to denote a region in which such vector fields have a significant magnitude.
NOTE 2?Vector field. The totality of vectors in a given region represented by a vector function ν(x, y, z) of the space coordinates x, y, z. A vector field (in this case, the magnetic field) associates a vector valued quantity (in this case, the magnetic field strength, H, or magnetic flux density, B) with every point in a given region.

6.7 magnetic flux density: The vector quantity, often denoted as B, of zero divergence at all points, which determines the component of the Coulomb-Lorentz force that is proportional to the velocity of a moving charge.
NOTE 1?. . .The vector properties of the magnetic flux density produced by currents in power-line conductors are the same as those given for the electric field strength in 6.3.1 ac electric field strength. The unit for the magnitude of the magnetic flux density components is the tesla (T).
NOTE 2?Some documents may refer to the magnitude of the magnetic flux density using gauss for the units. The unit gauss is related to the unit tesla by the equation 1 T = 10^4 gauss.
NOTE 3?For time-varying (ac) fields, values are expressed as their rms values unless stated otherwise.
NOTE 4?Though they are used often, the use of magnetic field or B-field is deprecated in favor of magnetic flux density.

6.9 ac power-line fields: Power-frequency electric and magnetic fields produced by ac power lines.

7.1.1 ac electric field strength meter: A meter designed to measure the power-frequency electric field strength. Two types of electric field strength meters are in common use....

7.7 magnetic flux density meter: A meter designed to measure the magnetic flux density. These meters may use any of several types of flux density sensors or probes....

11.1 electromagnetic signal: The intelligence, message, or effect to be conveyed over a communicationsystem or broadcasting system via electromagnetic waves.

You can further look at IEEE 644 - IEEE Standard Procedures for Measurement of Power Frequency Electric and Magnetic Fields From AC Power Lines to see that indeed measurement of electric and magnetic fields are done with separate instruments.

The standard for the different instruments for measuring electric and magnetic fields is IEEE 1308 - IEEE Recommended Practice forInstrumentation: Specifications for Magnetic Flux Density and Electric Field Strength Meters - 10 Hz to 3 kHz

Even though these standards are for transmission lines, ac fields are ac fields. The physics are the same.

Enough said?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I never said there wasn't an electric field and a magnetic field. Of course there are both. I was simply refering to your post about what EMF stood for.
Nows there's enough said.:grin:
 

stevero

Member
I never said there wasn't an electric field and a magnetic field. Of course there are both. I was simply refering to your post about what EMF stood for.
Nows there's enough said.:grin:

OK, but you did say "A gaussmeter will read emf's just fine." Not so with the electric field which I'm sure is the problem here. You need an e-field meter which reads V/m.
 
Last edited:

SAC

Senior Member
Location
Massachusetts
OK, but you did say "A gaussmeter will read emf's just fine." Not so with the electric field which I'm sure is the problem here. You need an e-field meter which reads V/m.

I'm not so sure about that - you might want to look into Maxwell's Equations. A time varying electric field generates a time varying magnetic field. I believe it's called "displacement current". So if that is an AC power line, an AC gaussmeter could detect the complementary magnetic field.
 

stevero

Member
Are you sure about that? I've never heard such

Look at my previous post. IEEE 644 and IEEE 1308 clearly specify E-field meters for 60 hz. I guarantee you that if you read the fields from an energized circuit carrying zero current with a 60-hz gauss meter you will read 0. GAUSS METERS READ GAUSS WHICH ARE MAGNETIC FIELD UNITS.

If you have lots of money you can buy an E-field meter from ETS Lindgren.com (Holaday HI 3604) or Enertech.net (EMDEX II with E-probe).
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
First time caller today says ever since she had about 100 stainless steel staples in her stomache from an operation, that she is very sensitve to EMF. She claims she cannot even sleep at night without turning ALL the breakers off in the entire house. She says the smart meter on her house puts off such a field that she can't go near it. She says that with all breakers off, she was managing to sleep ok, then her neighbor got a wireless router and is really messing her up. She supposedly can tell when her neighbor is moving data!! Could this woman be off her rocker? The problem is so bad, she wants it corrected immediately or she is moving. I told her that she is feeling something that does not affect 99.9% of people in America. HAs anyone dealt with this?

People who work at places that sell tobacco products occasionally get calls like this.

Store: Hello, Joe's tobacco shop.
Caller: Do you have Prince Albert in a can?
Store: Yes we do.
Caller: Better let him out of the can before he suffocates.
Click.

Perhaps you could suggest she get some tin foil and make herself a protective cap. Its necessary to use real tin foil, and not aluminum foil though, as aluminum foil does not have the protective benefits of tin foil. It's important to ground the tin foil cap with a #6 or larger, green insulated wire. Only green wire will work. She also needs static straps for her car for mobile protection.
 
Last edited:

mcclary's electrical

Senior Member
Location
VA
People who work at places that sell tobacco products occasionally get calls like this.

Store: Hello, Joe's tobacco shop.
Caller: Do you have Prince Albert in a can?
Store: Yes we do.
Caller: Better let him out of the can before he suffocates.
Click.

Perhaps you could suggest she get some tin foil and make herself a protective cap. Its necessary to use real tin foil, and not aluminum foil though, as aluminum foil does not have the protective benefits of tin foil. It's important to ground the tin foil cap with a #6 or larger, green insulated wire. Only green wire will work. She also needs static straps for her car for mobile protection.



Are you suggesting it was a prank call?. Because I don't think so. She was quite assertive with everything and the reason I didn't anything for her is she wanted somebody immediately and I could not accomodate
 

handy10

Senior Member
Go see the lady!

Go see the lady!

It seems to me that someone should actually go see the lady. When metal is placed in contact with the body, some strange things can happen. If you have silver fillings in your teeth, do chew aluminum foil. It doesn't much matter to the lady if her trouble is caused by emf or by induction or some other electrical phenomena. Perhaps there is some sort of arcing that is bothersome. Possibly, a very small amount of inductive current can cause her nerves to have a fit. The suggestion that she go back to the doctor is also a good one.
 

skeshesh

Senior Member
Location
Los Angeles, Ca
One of my roommates from college (biomedical engineer) is coming for a visit tonight. We'll have a fun topic to discuss. My first impression however is that she is a confused old lady.
 

rattus

Senior Member
Oddballs:

Oddballs:

One of my roommates from college (biomedical engineer) is coming for a visit tonight. We'll have a fun topic to discuss. My first impression however is that she is a confused old lady.

Anyone who has ever made service calls has encountered all sorts of oddballs Just out of the Army, I was working on this machine when this jerk starts griping at me. I was full of it then, so I asked if he wanted me to fix the machine or leave. He told me to leave! He called back later, but I refused to go back, so they sent someone else.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
It seems to me that someone should actually go see the lady. When metal is placed in contact with the body, some strange things can happen. If you have silver fillings in your teeth, do chew aluminum foil. It doesn't much matter to the lady if her trouble is caused by emf or by induction or some other electrical phenomena. Perhaps there is some sort of arcing that is bothersome. Possibly, a very small amount of inductive current can cause her nerves to have a fit. The suggestion that she go back to the doctor is also a good one.
I am pretty sure that no electrician can help this woman if it was not a crank call, other than somehow gently suggesting she contact a mental health professional. And there is not really a tactful way to do that, and because she is delusional she is not likely to be able to understand the need for professional mental health help. And really, even mental health professionals often cannot do much more than try to mask the symptoms, which while not real satisfying is better than nothing.

There are some people that even if you want to help them you are not going to be able to do so, and with someone who is perhaps not completely stable, you are not helping them by feeding their delusions.
 
Status
Not open for further replies.
Top