Gauss meters

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gar

Senior Member
Location
Ann Arbor, Michigan
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EE
080721-0956 EST

To those that have Gauss meters:

1. Why do you have one of these meters?
2. What is your use?
3. What is the resolution (smallest increment)?
4. Manufacturer and model number?
5. What type of sensor?
6. How large is the sensor head?
7. How often is it used?
8. Do you have customers that require these measurements?
9. Do you also have an electric field intensity meter?

I have a coil that I bought many years ago that is calibrated at 1 gauss @ 60 Hz = 20 MV. With my Fluke 27 this gives me a resolution of 5 mG. I have added a 200 gain amplifier thus improving the resolution to 0.025 mG. Currently my noise level is about 6 times this, or 0.15 mG. That should be correctable with filtering.

Some of my observations:

On the ground below my 3 phase primary lines I read about 0.05 mG above the noise level.

The ground current to my water pipe is about 110 MA. Using the probe it appears to flow both into the house and earth. Maybe equally or not, but it looks equal at this time. I do not have a large current probe to go around the water pipe so I can not perform a correlation.

All my water plumbing is copper, all vertical drains in the basement are cast iron. It is interesting that the magnetic field probe sees current in one of the drains in the basement. My water line runs under the basement floor, but with my present sensitivity and noise level I can not detect its location from the magnetic field probe and the low 55 MA current.

This is a coil type probe and therefore when not moving is insensitive to steady magnetic fields. It is interesting that when I move the probe I get a short time rise in the reading. This of course results from moving the coil in the earth's magnetic field.

.
 
gar said:
080721-0956 EST

To those that have Gauss meters:

1. Why do you have one of these meters?
2. What is your use?
3. What is the resolution (smallest increment)?
4. Manufacturer and model number?
5. What type of sensor?
6. How large is the sensor head?
7. How often is it used?
8. Do you have customers that require these measurements?
9. Do you also have an electric field intensity meter?(cut)
Click to expand...
1. I bought one for my mother.

2. She was worried about the residential pole xfm she could see out her bedroom window affecting the pyramid she put over her bed. So we went all over the house and mapped the magnetic field

3. 1mG(?)

4. Bought it from Scientific Atlanta (?) for $100 - no telling who made for them.

5. Unknown

6. The whole thing was smaller than a pack of playing cards.

7. It lasted about a week. Mom was getting ready to put up mu-metal foil on the bedroom wall. The fluorescents were going to all go. The television was going to get a leaded glass screen - then she found out that her sewing machine was the worst culprit. Since that couldn't be, that was the end of the project. As I recall, the pyramid went too. I haven't seen the meter in ten years.

8. no - But if I had customers I could vacuum money from - in return for an honest report, I'd do it in a minute - no, make that a second.

9. no

edited resolution (3)

cf
 
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after I read Tracing EMF's by Karl Riley, I picked up a relatively inexpensive xyz gaussmeter (+/- 0.1 mg) a year or two ago and use it for fun once in a while just to see the effects of bad wiring when I find it. I usually take it with me on vacations or to relatives houses and poke around when I'm bored to see if I can find bad wiring. That's a great book for 30 bucks and I think that the science is sound, regardless of the disputed health effects, it makes sense to reduce em fields if only from the standpoint of inefficiency and potential noise. I don't really see the need for anything more accurate that .1mg though. (for general use)

(I was introduced to this stuff 10 or so years ago by a buddy who had wired a guys house who was an engineer, and the guy had made him wire the house with no emfs -he went around after it was roughed-in and energized and made sure that there were no fields. )
 
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As I have stated before in this forum .
Don't poke fun at those who are concerned about emf.
Time and time again when we did troubleshooting for Edison the source of emf was exactly where the customer complained.
VOOOOODOOOOOOOOOOO:mad:
 
cf said:
1. I bought one for my mother....

7. It lasted about a week. Mom was getting ready to put up mu-metal foil on the bedroom wall.
cf
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It been a while since I mailed Floppie disc's, (wrapped in aluminum foil) but I was told to use the foil, shine side out to the elements !
 
I own several some inexpensive and one or two decent units. I use to utilize them all the time for ground investigations but with the advent of flat screens I have resorted to different methods.

All the name plate data is with the meter in my meter cabinet at work.

I avoid any investigations to due with health issues and work a engineer that does EMF work. He did a house starting price of the house was over 2,000,000.00 2 million. The lady hired him to do an EMF survey, brand new home she hired a contractor to tear up everything and everything marble, tile, hardwood, drywall and rewire add shielding and other such things. Then restore the house to the as found condition.
 
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080721-2118 EST

brian:

What is the flat screen device that you use to solve your ground problems?
What is the general nature of the ground problems you troubleshoot?
How did the Gauss meter help, and how does the new instrument differ in its function?

.
 
gar said:
080721-2129 EST

Sierrasparky:

What were the customers symptoms, and what were the ballpark field intensities?

.
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We worked for a company called Field management in Calif. They were directly reffered at the time from Socal Edison.
We had this one lady who said she had been nacious when she spent a lot of time in this one room of here beverly hills apartment. Sure enough the engineer from Field management found High levels about 30 gauss I think about 3 feet off the floor where she lounged on the couch. We actually found several miswired exit emergency exit signs and lights directly below this area. After removing the fixtures and sorting the nuetrals in the fixtures We removed the EMF. The lady was happy.

Another job had the family feel some sort of discomfort when at a paticular end of the house. I don't recall the Gauss level. What we found was a mis wired 4 way switch system down several long hallways. We wound up using some Master slave switches because there was no proper way to sort the travelers. The electrician made a huge magnetic field with his travlers.

We had a an architect that complaind about some headache or ssomething and that at about 10 am every day you could see his computer monitor flicker immensly. We found that the Domino's pizza had a miswired prep table outlet that caused a several hundred feet ground loop that ran under the Arch's desk. We fixed the problem and he was better.

I don't know what the threshold is I have not worked for that company for over 10 years now. My current situation people think its Voodoo so I down play it. I do check for net currents as that is a good indicator of Emf related problems.

I hope that's not too much info.
 
080722-0650 EST

Sierrasparky:

This is interesting and would appear to provide some proof of a physiological effect from moderate AC power frequency magnetic fields. I looked back at the other thread on EMF and found your previous comment.

Your one level of 30 mG is consistent with 15 A in a single wire at 1 meter distance.

My intent of this thread was not to address the human exposure problem, but so far that seems to be the direction.

This morning I did a quick search in Google and found this reference:
http://books.nap.edu/openbook.php?record_id=5155&page=28
This is interesting.

Just a sample on electric field intensity:
----- With that caveat, EPRI found that the mean personal exposure to 60-Hz electric fields in the home or office typically ranges from 5 to 10 V/m.

Power-line electric fields have been well characterized; depending on line voltage, ground-level electric fields under a line might be as high as 10 kV/m, which is sufficient to cause fluorescent tubes to glow and to induce shock currents in a person who touches a vehicle parked under a high-voltage line. Mean personal exposure to electric fields for substation, distribution-line, and transmission-line workers ranges from 50 to 5,000 V/m (EPRI 1990). -----
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The typical height of a person is in the ballpark of 2 meters. Thus, maybe 10,000 V from head to toe. Obviously a person is a conductor and modifies this field. The actual voltage across the body will depend upon the current and body surface resistance. How many linemen feel bad in these high electric field intensities?

This same reference also discusses magnetic field intensities.

.
 
I hope it helped.
I never did get involved in the calculations.
I was told that the levels dropped off considerable after you double the distance.

We did a video tape vault once. They had to lead line the place because of emf.
 
080722-0814 EST

Sierrasparky:

The equation for magnetic flux density from a single long straight wire is

B = 2*I/R
where
B is flux density in mG
I is current in amperes
R is the radial distance from the wire to the field intensity point

Thus, 30 mG at 1 meter becomes becomes 6 mG at 5 meters.

.
 
gar said:
080722-0814 EST

Sierrasparky:

The equation for magnetic flux density from a single long straight wire is

B = 2*I/R
where
B is flux density in mG
I is current in amperes
R is the radial distance from the wire to the field intensity point

Thus, 30 mG at 1 meter becomes becomes 6 mG at 5 meters.

.
Click to expand...
Thanks :)
 
What is the flat screen device that you use to solve your ground problems?
Click to expand...

CRT monitors experience screen shake, with the advent of flat screens the service calls for this issue disappeared.

What is the general nature of the ground problems you troubleshoot?
Click to expand...

90% are improperly grounded neutrals downstream from the main neutral bond, by this accidental or intentional. Did a building last week and every disconnect (maybe 40 or more) had the neutral bonded with the ever present GREEN SCREW, and/or a NEC sized bonding jumper. Additionally we located numerous branch circuits with ground connections.


How did the Gauss meter help, and how does the new instrument differ in its function?
Click to expand...

Utilized it in tracing the source of the issues.

.
 
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