Electrician Talk banner

Best Wiring Method To Avoid EMF

21413 Views 41 Replies 21 Participants Last post by  brian john
Hi guys,

I've got a customer who wants my company to re-wire some of his receptacles in his bedroom to lessen the amount of EMF he's picking up with his Gauss meter. I have no experience in this.

Some of the material options I could re-wire with would be:
1. MC cable
2. Aluminum flex
3. Steel flex
4. Romex, but twist the Romex

Anybody know anything about this?
1 - 20 of 42 Posts

· Registered
Joined
·
2,321 Posts
Shield the room with copper mesh. Did he/you shut off the main to determine how much EMF he's reading from other sources? In many cases the home wiring is not a significant contributor.

Don't forget to wear your best tinfoil hat. If you put some egg salad between the layers it's much more effective.
 

· Registered
Joined
·
572 Posts
Many times the EMF source is what's plugged into or connected to the wiring.

As far as what wiring method works best to elliminate EMF's, it's not really a wiring type issue it's how the wiring is installed. Simply make sure there is current flow in both directions in order to negate it and that there are no currents flowing in conductors or conductive paths that it is not supposed to be flowing on.

IOW's, the short and simplified answer is, there should be a hot / hot, hot / neutral, or hot and switch leg in every cable or raceway and make sure there is no current leaking to a coax, LV cable shield, or anything else.
 
  • Like
Reactions: LAElectrician

· LAElectrician
Joined
·
263 Posts
Discussion Starter · #4 ·
Shield the room with copper mesh. Did he/you shut off the main to determine how much EMF he's reading from other sources? In many cases the home wiring is not a significant contributor.

Don't forget to wear your best tinfoil hat. If you put some egg salad between the layers it's much more effective.
Well, of course the first thing to always check for is microwave beams coming in from the NSA satilites that are spying on him.

But really, he has his own Gauss meter and it only reads "excessive EMT" on 10 specific receptacles in his house, and he wants to bring new wires to them. The question is, which wiring method is best to reduce the EMF footprint?
 

· Registered
Joined
·
2,321 Posts
Well, of course the first thing to always check for is microwave beams coming in from the NSA satilites that are spying on him.

But really, he has his own Gauss meter and it only reads "excessive EMT" on 10 specific receptacles in his house, and he wants to bring new wires to them. The question is, which wiring method is best to reduce the EMF footprint?
The best thing to do is ensure those branch circuits are wired correctly, in other words, no neutral-to-ground contact, hot and neutral are no reversed, etc. If any of those circuits feed a 3-way switch circuit, be sure there is no single phase conductor not paired with a neutral in the same cable. In other words, solid wiring methods executed properly will result in "safe" wiring in all respects. Even "consultants" who specialize in low-EMF home wiring recommend this. If the house is wired properly, EMF should be very low.
 

· Registered
Joined
·
11,734 Posts
Twist the current carrying THHN conducters and place them in EMT/heavy guage conduit with an indivdual ground conducter on the side. Switch both hot and neutral simatanously at the switches. Consider using an isolation transformer for the 120 volt system and a contacter to turn off the bedroom circuits if that is of concern. Dont run anything behind or under the bed frame areas. Run conduits as short as possible.

Dont use twisted romex, its not worth it. Some MC even becomes pre twisted.

I know theres more but its been a while since I did a low EMF house.
 

· LAElectrician
Joined
·
263 Posts
Discussion Starter · #10 ·
The best thing to do is ensure those branch circuits are wired correctly, in other words, no neutral-to-ground contact, hot and neutral are no reversed, etc.
You wrote "no neutral-to-ground contact", but the neutral will eventually be grounded at the main panel, right?
 

· Registered
Joined
·
572 Posts
You wrote "no neutral-to-ground contact", but the neutral will eventually be grounded at the main panel, right?
That is correct but that is the only place, after that you would be paralleling the neutral as far as current flow is concerned and this leads to non canceling currents
 

· Administrator
Retired EC
Joined
·
24,903 Posts
There are 3 basic causes for emf's in a home. NM cable is perfectly ok but if he has more than 2 mlligauss when the lights are on then there is an isssue.

1. neutral and egc are touching after the load

2. Neutrals from one circuit are tied to neutrals from another circuit.-- I have found this in switch boxes where there are 2 feeds in a 3 gang box and all the neutrals tied together-- easy fix

3. If the circuit is run and the neutrals and hot conductors are not run together as IN knob and tube wiring and some 3 way installs.
 

· LAElectrician
Joined
·
263 Posts
Discussion Starter · #13 ·
1. neutral and egc are touching after the load

2. Neutrals from one circuit are tied to neutrals from another circuit.-- I have found this in switch boxes where there are 2 feeds in a 3 gang box and all the neutrals tied together-- easy fix
1. What does egc mean?

2. Is it OK to run a three wire circuit (two hots sharing one neutra)l, or do you think it's better to run a dedicated hot and neutral
 

· Registered
Joined
·
282 Posts
On shielding:

a] For low frequencies (power line), soft steel work's best.

b] For radio frequencies, copper or aluminum work's best. But aluminum is harder to make good joins & connections.

c] Lead is for X-rays and sound absorption.

d] Ralph Morrison in his book "Grounding and Shielding: Circuits and Interference" on page 180 writes about building a screened room laboratory.

e] Page 13 of this paper has some power line noise tests.

Integrating Electronic Equipment and Power into Rack Enclosures
Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems

http://www.middleatlantic.com/pdf/PowerPaper.pdf

f] Twisting current carrying wire pairs is always good. The more twists per foot the higher the frequency, that it's good for.
 

· Registered
Joined
·
799 Posts
I have to tell you all this story.

We have a local EC that sells a lot of power quality and loves to scare people with his Gauss meter. He extols the perils of magnetic fields and I think 90% of his business is related to EMF.

My story involves a young down to earth family in their first house. The have this EC do a EMF check on the house and as part of a whole house renovation decide to also rewire. The EC recommends AC-90 as the armour helps shielding. The house was Knob and tube so we did expect to see some EMF.

I am in the house doing a rough wire inspection and in speaking to the homeowner I notice she is wearing a haematite bracelet. This is a form of magnetic glass-like material. IE it looks like black glass but is metal. I ask her this. I see you are wearing a magnetic bracelet? Yes it helps with the bodies healing mechanisms. Oh how interesting. But you are spending an extra few hundred dollars to eliminate magnetic fields from your house? Isn't that contrary to the reason you are rewiring the house with BX instead of NMSC? Blank stare!

I pretty much dropped it there except to reassure her the wiring was some of the best I have seen from this ec and maybe they should always work with bx.

I did not want to get into an ac field versus steady fields or other stuff I don't believe. My other favourite story is the smart meter protester with a cell phone next to her head but that is another story :whistling2:
 

· Administrator
Retired EC
Joined
·
24,903 Posts
1. What does egc mean?

2. Is it OK to run a three wire circuit (two hots sharing one neutra)l, or do you think it's better to run a dedicated hot and neutral
EGC is equipment grounding conductor

Yes you can share a neutral but with afci breakers being required I would not do that.
 

· LAElectrician
Joined
·
263 Posts
Discussion Starter · #17 ·
EGC is equipment grounding conductor

Yes you can share a neutral but with afci breakers being required I would not do that.
Thanks for the info. And yes, since most EMF issues usually concern the living and sleeping areas of the house, AFACI dedicated circuits are almost always going to be used, but I was just wondering about three wire circuits and EMF.
 
1 - 20 of 42 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top