WIFI, RF & EMF

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Good Morning Everyone.
I was sent this email from a potential customer and was hoping someone has has some experience with this or could lead me to some good info to study.

Thanks.

I have been reading that WIFI, RF, EMF etc can affect a persons health. We have little children and I just do not want to take a chance being that we have 3 cell towers within .5 mile of the house.


In order to block smart meters, neighbors RF traffic and Cell signals you apparently have to ground the siding. In effect, it will create a sorta faraday cage and block signals from coming in or out. Also if lightning ever does hit, or a light/switch somehow energizes the siding then we will be covered.
 

DarylH

Member
Location
San Marcos, CA
Good Morning Everyone.
I was sent this email from a potential customer and was hoping someone has has some experience with this or could lead me to some good info to study.

Thanks.

I have been reading that WIFI, RF, EMF etc can affect a persons health. We have little children and I just do not want to take a chance being that we have 3 cell towers within .5 mile of the house.


The RF levels from WiFi hot spots are really low. They are authorized by the FCC under Part 15 of 47 CFR. I have added a link to the Part 15 rules below. Part 15 covers a variety of wireless devices but not cell phones and other radio classes which are authorized under other rule parts.

http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=f79745a529d74b63f0154e56495811be&r=PART&n=pt47.1.15

To help the public understand issues regarding RF safety, the FCC has a RF safety FAQ page at:
http://www.fcc.gov/encyclopedia/radio-frequency-safety

Each time an application for a RF emitting device or service is submitted to the FCC for approval, an evaluation of compliance with RF Safety limits needs to be performed. The OET has produced Bulletin 65 which gives guidelines for determining compliance. There's a link to Bullletin 65 on the FAQ page above.

The exposure limits vary a bit by frequency, but for example, in the case of the satellite communications equipment I work with, the level for general population exposure is 1 mW/cm^2 over a 30 minute averaging period.

This means that any square cm of area on a person should not see RF levels greater than 1 mW averaged over any 30 minute period. You could therefore be exposed to a field that is 15 mW/cm^2 for 2 minutes then nothing for the next 28 minutes, or any combination that adds up to the 1 mW/cm^2 over 30 min.

RF fields vary with the distance or as the square of the distance depending on whether or noth they are in the near or in the far field. OET 65 gets in to that. Most of the time exposure will be in the far field from cell towers and probably WiFi hot spots too. This means that if you double the distance the RF exposure is reduced by four times, i.e., the square of the change in distance.

OET Bulletin 56 gets into the biological effects of RF exposure. RF exposure is not ionizing like nuclear radiation - even though the term RF radiation is used. Rather, it causes tissue heating through the accelerated movement of molecules in your body. The reason an averaging period is used is because your body will dissipate some of the heat through blood flow and natural cooling processes - just like going into a sauna for 15 minutes then coming out.

it is likely you/they have nothing to worry about, but it never hurts to read up and then have a go at the calculations yourself.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I have dealt with 6 or so customer who swear that the electromagnetic field's cause them problems. Who know's for sure but if there is a worry then why not help them out. A gaussmeter is important to own in these cases and you can get fairly cheap ones for starters.

The are 3 common causes in a residence for electromagnetic field's.

Common Causes of EMF

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.
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.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Basically you are looking for anywhere the neutral and hot of a circuit are not run together or where the neutral is give another path back to the source without the hot conductor For instance Knob & Tube will cause high levels of electromagnetic field's depending on the load on the circuit. Two gang boxes where 2 different circuits land one will often find all the neutrals tied together.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
I have dealt with 6 or so customer who swear that the electromagnetic field's cause them problems. Who know's for sure but if there is a worry then why not help them out. A gaussmeter is important to own in these cases and you can get fairly cheap ones for starters.

The are 3 common causes in a residence for electromagnetic field's.

Common Causes of EMF

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.
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.

Excellent post! Hard to find info on the subject but you are spot on.

Thanks :)
 

DarylH

Member
Location
San Marcos, CA
I have dealt with 6 or so customer who swear that the electromagnetic field's cause them problems. Who know's for sure but if there is a worry then why not help them out. A gaussmeter is important to own in these cases and you can get fairly cheap ones for starters.

It never hurts to verify levels are within limits, but I've had several cases where people swore there were real physical problems occurring for no valid reason.

One of them was about 25 years ago in the town of Franklin, NJ. The people of the town were claiming thing like their cows milk was drying up and their cats fur was falling out, etc. This was because my company was installing two large earth station antennas (11 m and 13 m) and they thought the RF signals were doing them damage.

I was tasked with doing the RF exposure calculations for the earth stations and the result were going to be presented at a town meeting by one of our lawyers. The calculations showed the levels were quite low outside our perimeter fence and well within FCC limits.

At the meeting the townspeople said calculations didn't matter - they were seeing real problems! Our lawyer then simply pointed out that while the antennas had been installed, our radio equipment and power amplifiers had not been delivered yet and the site was not currently capable of transmitting.

Needless to say, the many town folk still didn't believe us but we were still allowed to proceed with the installation and there were never any complaints after that - even when we were on the air.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
My suspicion is there is stray voltage present in the ground near the dairy cattle and they are getting shocked-- this may cause them anxiety and they may not produce the milk.
 

fmtjfw

Senior Member
It never hurts to verify levels are within limits, but I've had several cases where people swore there were real physical problems occurring for no valid reason.

One of them was about 25 years ago in the town of Franklin, NJ. The people of the town were claiming thing like their cows milk was drying up and their cats fur was falling out, etc. This was because my company was installing two large earth station antennas (11 m and 13 m) and they thought the RF signals were doing them damage.

I was tasked with doing the RF exposure calculations for the earth stations and the result were going to be presented at a town meeting by one of our lawyers. The calculations showed the levels were quite low outside our perimeter fence and well within FCC limits.

At the meeting the townspeople said calculations didn't matter - they were seeing real problems! Our lawyer then simply pointed out that while the antennas had been installed, our radio equipment and power amplifiers had not been delivered yet and the site was not currently capable of transmitting.

Needless to say, the many town folk still didn't believe us but we were still allowed to proceed with the installation and there were never any complaints after that - even when we were on the air.

Another case of the inverse-placebo effect.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
As a matter of physics, grounding the siding won't create a Faraday cage. That would require mesh on the windows and several other things.
But it would still reduce the RF signal inside of the house. My house has aluminum siding and foil backed drywall with no attempt to ground either the siding or the drywall foil, yet outside we have 4 bars and inside, unless at a window, we have about 1 bar. Calls were often dropped because of the poor signal strength inside the house.

A number of years ago AT&T sent us a micro-cell for our house. It acts as a mini-cell tower and connects to the cell system via the internet. No more dropped calls, but I am sure that if someone was looking at RF levels they would be much higher with the micro-cell than they were before we had that device.
 

DarylH

Member
Location
San Marcos, CA
The AT&T Microcell (which is really more a pico cell) has the following RF exposure compliance statement in the user manual:

"Radiation Exposure Statements
Note: This transmitter must not be collocated or operated in conjunction with any other antenna or transmitter. This equipment should be installed and operated with a minimum distance of 7.9 inches (20 cm) between the radiator and your body.

United States
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This system has been evaluated for RF exposure for humans in reference to ANSI C 95.1 (American National Standards Institute) limits. The evaluation was based on evaluation per ANI C 95.1 and FCC OET Bulletin 65C rev 01.01. The minimum separation distance from the antenna/radiator to a general bystander is 7.9 inches (20 cm) to maintain compliance. This transmitter must not be collocated or operating in conjunction with any other antenna or transmitter.
The availability of some specific channels and/or operational frequency bands are country dependent and are firmware programmed at the factory to match the intended destination. The firmware setting is not accessible by the end user."
So basically, as long as the user is 7.9 inches away or more from the device the RF levels are below the exposure limit.

The FCC is really strict about RF exposure levels and chances are that if there's a cell phone tower within 0.5 miles of a house, the RF levels have been vetted up one side and down the other.
 

FionaZuppa

Senior Member
Location
AZ
Occupation
Part Time Electrician (semi retired, old) - EE retired.
Good Morning Everyone.
I was sent this email from a potential customer and was hoping someone has has some experience with this or could lead me to some good info to study.

Thanks.

I have been reading that WIFI, RF, EMF etc can affect a persons health. We have little children and I just do not want to take a chance being that we have 3 cell towers within .5 mile of the house.


In order to block smart meters, neighbors RF traffic and Cell signals you apparently have to ground the siding. In effect, it will create a sorta faraday cage and block signals from coming in or out. Also if lightning ever does hit, or a light/switch somehow energizes the siding then we will be covered.

along with all the other posts...... well, tell the person concerned to move if they feel its an issue.
also, using any sort of meter at a single location is kinda pointless as this does not capture interference patterns. its very possible a person can be exposed to high power density at interference points, one really needs a 3D map to accurately describe what the power densities looks like in the space you move around in, etc.

you could also paint the inside of your home with paint primer that has metallic particles in it, this will help some to reduce ingress Rf. the affects of Rf at power densities at or below FCC regulations does not have any obvious side affects, but one really needs good control data to compare to, which is about impossible unless there's a whole city living in Rf isolation for ~100yrs.

i guess you can look at it this way, if Rf exposure takes 5yrs off human life but modern medicine is giving back 10yrs, you are netting +5 for the "convenience" of both.

my guess is though, people may just feel better knowing they have very very low or no Rf exposure from human made crud, and this is likely due to the power of the brain.
 

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
People afraid of the RF that a cell phone or WiFi creates should just wear a tinfoil hat. Double thick if they feel like it. RF is non-ionizing radiation. It does not have the energy necessary to cause damage to living tissue in the manner that ionizing radiation, such as x-rays, gamma rays, etc... does.

RF energy, at a high enough power density can cause local heating of people and materials. That's why they have to shut down (or at least turn the power down) the 100kW AM radio towers in order to send the guy up to change the light bulbs. If your cell phone is outputting 100kW, I want to see the batteries you're using!

RF causes heat; it does not damage tissue on the molecular level (DNA damage).

RF energy has always been present, even before humans discovered electricity and radio. Lightning and other natural phenomenon produce plenty of broadband noise, often at much higher power levels than a cell phone. If you don't believe me, try listening to the AM radio during a thunder storm.

Pseudoscience crap such as this really bugs me. This is right up there with pyramid power and alien mind control.



SceneryDriver
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
People afraid of the RF that a cell phone or WiFi creates should just wear a tinfoil hat. Double thick if they feel like it. RF is non-ionizing radiation. It does not have the energy necessary to cause damage to living tissue in the manner that ionizing radiation, such as x-rays, gamma rays, etc... does.

RF energy, at a high enough power density can cause local heating of people and materials. That's why they have to shut down (or at least turn the power down) the 100kW AM radio towers in order to send the guy up to change the light bulbs. If your cell phone is outputting 100kW, I want to see the batteries you're using!

RF causes heat; it does not damage tissue on the molecular level (DNA damage).

RF energy has always been present, even before humans discovered electricity and radio. Lightning and other natural phenomenon produce plenty of broadband noise, often at much higher power levels than a cell phone. If you don't believe me, try listening to the AM radio during a thunder storm.

Pseudoscience crap such as this really bugs me. This is right up there with pyramid power and alien mind control.

PSMJ Pseudo Scientific Mumbo Jumbo

There was a New Age bookstore here that had a bunch of quartz crystals laid out on black velvet at their checkout counter. If you picked one up while you were waiting in line the clerk would insist that now you had to buy it since when you touched it it "aligned its aura to yours" and they could not sell it to anyone else. Of course, if you were in that store in the first place there is a nonzero probability that you were self selected to be susceptible to that line of BS. :D
 
Last edited:

mbrooke

Batteries Included
Location
United States
Occupation
Technician
People afraid of the RF that a cell phone or WiFi creates should just wear a tinfoil hat. Double thick if they feel like it. RF is non-ionizing radiation. It does not have the energy necessary to cause damage to living tissue in the manner that ionizing radiation, such as x-rays, gamma rays, etc... does.

RF energy, at a high enough power density can cause local heating of people and materials. That's why they have to shut down (or at least turn the power down) the 100kW AM radio towers in order to send the guy up to change the light bulbs. If your cell phone is outputting 100kW, I want to see the batteries you're using!

RF causes heat; it does not damage tissue on the molecular level (DNA damage).

RF energy has always been present, even before humans discovered electricity and radio. Lightning and other natural phenomenon produce plenty of broadband noise, often at much higher power levels than a cell phone. If you don't believe me, try listening to the AM radio during a thunder storm.

Pseudoscience crap such as this really bugs me. This is right up there with pyramid power and alien mind control.



SceneryDriver

Perhaps, the public has fallen for the conditioning... have a potential major issue be covered up by depicting honest questions as the manifestations of insanity...


Anyway, I disagree with your statement regarding RF/cell phone towers. Yes I can point to studies that claim there is no link to health effects but I can also point to studies that say otherwise. At this point the issue is heavily debated, and not fully understood. To say its either way is false.


High frequency RFI could be harmless, it could be only a slight risk, it could only effect sensitive people, or it could be a major risk, its hard to prove because so many variables are involved in addition to political/financial influence. By that I mean if there is a known risk admitting it would be a great burden for Cell phone companies. Also, keep in mind that when something becomes so widespread finding controls in scientific testing is difficult since everyone is so exposed to WIFI and the like these days.

I keep an open mind and not fall into the hype that pulls in all directions.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
Just to add to my other post:

I try not to worry about things I cant control. I cant stop my neighbors from using WIFI or those cell towers popping up across town, but I can do things to help myself. I keep my cell phone in another rooms when I sleep, try to use ear buds (headphones) when on a cell phone. I make sure my home has no wiring errors (a biggy IMO), try not to keep my tablet/laptop on my lap. Eat healthy (little processed food, organic when possible) and stay active. I find those common sense steps reap the most benefit of all else. :D
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
IMO, it does not matter what I believe about the issue. If the customer has issues with it then so be it- I will try and do what I can to alleviate it. I have no doubt that there are those that probably like to think this is the answer to all their woes but I don't doubt that some are sincere and can feel the effects. Because I don't feel it or understand it should not be the criteria for me to judge another.

My wife can feel the weather change because it often initiates a migraine. Others are sensitive to paints or chemicals that don't bother others. There is a certain red dye used in cake icing that I can taste but others can't-- extremely bitter to me. Anyway, the list goes on
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
You are correct non-ionizing radiation is no where near as dangerous. You are also correct that the earth and space radiate plenty of EMFs, but that is only half a picture. Man made EMFs are much different, and our bodies have never adapted to them. Best example is when people say yes wires emit a magnetic field, but so does the earth. Correct, however the earths field is mostly constant, while wire EMF changes 50/60 times a second and is inductive. Such fields never existed in the history of evolution, but do now.


Sure, higher levels show a direct correlation to human tissue heating (food in a microwave oven), but lower levels are still being studied. Even if it doesn't ruin the DNA structure, fields can in theory (and some have been proven) to effect the endocrine system, hormones that control the sleep wake cycle, and nervous system. Its those small changes that are still being studied and so far only pieces of a very complex puzzle are being put together.


If you don't believe me for starters theres a Bee hive study where a cell phone was put in the Bee hive and Bees stopped returning to it...


I tried editing my prior post to add this in but I cant... 15 minute limit. One reason I liked it when Electrician Talk forum let you have several days to edit but took that away...:roll:
 
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