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It is complicated. I don't think your engineer friend is correct. Mostly the biology interaction deals with magnetic fields which are a product of the current flow.
In general buried local lines don't get to those kind of fields. Note that the environment is rich in sources. CRTs are an obvious and wide spread source.
I don't believe it is in general a problem. But it can be in close proximity to a major transmission. That is close...not a block away. And note it may well be the intermediate size transmission lines that cause the problem as they get closer than do the big transmission lines.
EMI (Electro Magnetic Interference) is the magnetic fields that happens to be 60 HZ in nature. If lines are below the ground, the fields are MUCH more intense because they are closer to you versus being 50 feet up in the air. As I explained earlier, the magnitude has an exponential relationship.
It would be my hope that the power companies would put the wires in a shield (a.k.a. a Faraday cage) which would dissipate the energy to earth ground. I am not in the power distribution business but I'd assume that (if done right) the EMI would be much less.
EMI (Electro Magnetic Interference) is the magnetic fields that happens to be 60 HZ in nature. If lines are below the ground, the fields are MUCH more intense because they are closer to you versus being 50 feet up in the air. As I explained earlier, the magnitude has an exponential relationship.
It would be my hope that the power companies would put the wires in a shield (a.k.a. a Faraday cage) which would dissipate the energy to earth ground. I am not in the power distribution business but I'd assume that (if done right) the EMI would be much less.
The thing is, power lines don't radiate significant amounts of energy. That'd make them great antennas and really bad at transferring power. Any energy that is radiated is energy that is lost, which costs the utility company money.
So the engineers that design them work very hard to make them as least lossy as possible, and that's why no shield is required.
You can do an easy test - drive up to big power lines and turn on your AM radio. You'll hear noise when you're really close but it's not very much. On the other hand, you'll hear noise from AM radio stations even though they are a long way away - because they have very efficient antennas designed to spew EMI into the air.
Cell phones, cordless phones, wireless internet routers, garage door openers, wireless printers are all examples of intentional radiators in our home. Everything else that operates with electricity is an unintentional radiator of EMI.
High voltage power lines generally do not radiate significant amounts of EMI as compared to other sources.
The thing is, power lines don't radiate significant amounts of energy. That'd make them great antennas and really bad at transferring power. Any energy that is radiated is energy that is lost, which costs the utility company money.
So the engineers that design them work very hard to make them as least lossy as possible, and that's why no shield is required.
You can do an easy test - drive up to big power lines and turn on your AM radio. You'll hear noise when you're really close but it's not very much. On the other hand, you'll hear noise from AM radio stations even though they are a long way away - because they have very efficient antennas designed to spew EMI into the air.
Cell phones, cordless phones, wireless internet routers, garage door openers, wireless printers are all examples of intentional radiators in our home. Everything else that operates with electricity is an unintentional radiator of EMI.
High voltage power lines generally do not radiate significant amounts of EMI as compared to other sources.
I hear what you are saying. Let's change the acronym from EMI to EMF. F standing for the Field. Or Electro Magnetic Field. The power line fear has less to do with the "I (Interference) and everything to do with the F in Field (so the theory goes).
So in summary, people don't want to be soaking in magnet fields day in and day out. Now. I'm thinking that it's over blow. But all things being equal, I'd rather not have my family living in a home with power lines overhead. Worse yet, it they didn't use a Faraday cage, I'd hate to have an exponentially higher magnetic fields from burred power lines.
Rest assured magnetic fields are alive and well overhead. If they transferred the same amount of current underground, the proximity to the wires would be exponentially more intense. It would be child's play to tame an underground transmission line by wrapping the wire in chicken-coop like material which would naturally bled off the field.
I've worked on magnetic deposition materials for 5 years at Honeywell using AC fields to align the magnetic materials. Sometimes fields got up to 10,000 Oersted's. you don't want two metal objects ine ach one of your pockets if you are a male. That is some serious fields and I didn't like sticking my body inside of it day in and day out. I've done more than a few hours or research on the topic. Personally I've experienced zero issues other than the strong desire to post on forums.
I hear what you are saying. Let's change the acronym from EMI to EMF. F standing for the Field. Or Electro Magnetic Field. The power line fear has less to do with the "I (Interference) and everything to do with the F in Field (so the theory goes).
So in summary, people don't want to be soaking in magnet fields day in and day out. Now. I'm thinking that it's over blow. But all things being equal, I'd rather not have my family living in a home with power lines overhead. Worse yet, it they didn't use a Faraday cage, I'd hate to have an exponentially higher magnetic fields from burred power lines.
Rest assured magnetic fields are alive and well overhead. If they transferred the same amount of current underground, the proximity to the wires would be exponentially more intense. It would be child's play to tame an underground transmission line by wrapping the wire in chicken-coop like material which would naturally bled off the field.
I've worked on magnetic deposition materials for 5 years at Honeywell using AC fields to align the magnetic materials. Sometimes fields got up to 10,000 Oersted's. you don't want two metal objects ine ach one of your pockets if you are a male. That is some serious fields and I didn't like sticking my body inside of it day in and day out. I've done more than a few hours or research on the topic. Personally I've experienced zero issues other than the strong desire to post on forums.
Faraday cages are ineffective against magnetic fields particularly of the ELF sort. You need high permeability metal shields such as mu metal.
In general for a lot of reasons mag fields from underground lines are not likely to be a problem. Worry more about building and complex distribtuion schemes. The danger is unbalanced currents of high magnitude. .
Faraday cages are ineffective against magnetic fields particularly of the ELF sort. You need high permeability metal shields such as mu metal.
In general for a lot of reasons mag fields from underground lines are not likely to be a problem. Worry more about building and complex distribtuion schemes. The danger is unbalanced currents of high magnitude. .
It's been 15 years since I was messing with all of that. I've done my best to forget it. You re-scratched my brain. We did have to work with mu metals which acts like a "flux sucker". Mu metal can only "suck" so much flux and it would be impractical / impossible to contain massive 120 HZ fields.
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F standing for the Field. Or Electro Magnetic Field. The power line fear has less to do with the "I (Interference) and everything to do with the F in Field (so the theory goes).
That is some serious fields and I didn't like sticking my body inside of it day in and day out. I've done more than a few hours or research on the topic. Personally I've experienced zero issues other than the strong desire to post on forums.
