EMF radiation from inverter?

[inetdog]

It has to do with the Operator old switch board cross-connect cable just like you phono Jack you plug into your cell phone for ear buds. Tip for the end of the plug electrical contact, followed by and insulator, and then Ring electrical connections completing the return circuit.

And the third electrical connection, used some of the time inside the switchboard or CO, was the remaining part of the plug, called the sleeve.

[Sunking]

thanks for the explanation.

My granddad's brother's house had a party line. I remember picking up the phone in ~1978 and hearing the other house. That's the only time I've ever run into one.

Was standard practice from the early 1900's to the end of the 70's. Phone companies just did not have that much copper buried and strung up. Plus the technology did not allow for every one to have a private channel and had to share. But it is not completely gone yet. Even in the USA there are still some Party Lines out there. Example Indian Reservations, Hill Billies in AR, NC, and TN and other remote rural area stil use them where copper facilities do not exist. Erricson and Nokia (formely Alcatel Lucent) the two switch manufactures left still support Party Lines in their Subscriber Line Equipment.

In Central and South America Party Lines are still common. But here in the USA land line phone companies are a dead end biz and will soon be 8-Track tapes and Buggie Whips.

Catch is you have to have a special phone with Frequency Selective Ringer. In the old days before deregulation you could only buy a phone from the phone company who would wire and configure the phone for you.

[DanKegel]

thanks for the explanation.

My granddad's brother's house had a party line. I remember picking up the phone in ~1978 and hearing the other house. That's the only time I've ever run into one.

[Sunking]

Back to the original OP worries about EMF. Unfortunately people are paranoid and our government makes it worse. Our Government lumps all of energy into the EMF title which is nonsense. EMF = Electromagnetic Fields. or Electric Magnetic Force. Both means the exact same thing. EMF occurs at power frequencies of 0 Hz (DC) to 300 Hz. Our stupid fear mongering government keeps the public in the dark and calls all energy and radiation EMF from DC to Gamma Radiation. The only distinction they make is Non-Ionizing radiation which is considered harmless to humans from DC up to visible light, and Ionizing radiation which is hazardous to humans from Ultraviolet light to Gamma rays.

EMF from power lines or power sources is magnetic just like any magnet produces. It does not radiate from the source like radio, light, X-Rays and Gamma Rays. The Magnetic Field produce are only evident if you are very close to the source and decay very quickly with distance.

The strongest EMF fields produced in public are those from High Voltage Transmission lines from the Generating Plant to the Cities. At the distance of 1 foot produce 90 Milligause of a magnetic field. 90 Milligause is not enough to do any harm with long tern exposure. At a distance of 200 feet the magnetic field from high voltage power lines decays into back ground noise level of 2 milligause levels which is caused by Earths magnetic fields.

Many studies have be done on EMF. After 30 years there is no evidence EMF is harmful. Test are still ongoing using Electric Power Companies Lineman who are constantly exposed to high EMF. In 30 years that group has no higher rate of cancer or illness than any other group.

Back to our Government and the two most paranoid agencies there are, OSHA, and the Employment Prevention Agency (EPA). Take a look at their guidelines on EMF exposure. Go ahead and look, there are none. Neither agency has any requirements or guidelines. What they do say is: If you have concerns about EMF is to stay 1 arm length away form appliances and electrical power equipment. Beyond that distance the EMF fields decay to background noise.

SK says if you are concerned about EMF, Wear a Tin Foil Hat so the rest of us know to stay away from you.

Hell you can buy bracelets, necklaces and ankle bracelets made from magnets to use the healing power from magnets. Magnets are strong EMF sources. Are you scared of a magnet? Do you play with them?. Do you use them to stick things on your refrigerator?

[Sunking]

Three wire connection? Strange! I think ours (BTE, in Blacker House at Caltech) only needed two wires to each phone.

Back in the days when there were party lines, it required 3-wires for the Ringers to work. Back in those days the Telco applied Ring Voltage between Tip-Ring, Tip-Ground , and Ring-Ground, or 3-mode at Frequencies of 20, 30, 40, and 50 Hz. That allowed them to put 12 homes on a single party line. Stilll used in some remote rural areas like Indian Reservations.

But today for most of us with private lines it is all 2-wire 20 Hz Ring circuits called Tip and Ring. FWIW Ring Conductor has nothing to do with Ring Voltage. It has to do with the Operator old switch board cross-connect cable just like you phono Jack you plug into your cell phone for ear buds. Tip for the end of the plug electrical contact, followed by and insulator, and then Ring electrical connections completing the return circuit.

[inetdog]

Three wire connection? Strange! I think ours (BTE, in Blacker House at Caltech) only needed two wires to each phone.

Three wire connection to phone usually is actually two line wires, one of which is grounded most of the time, and a ground. Where the ground is needed for some oddball ringing options instead of across the line ringing.

[jflorey2]

I also worked on those in the early '70 at MIT. I do not recall needing a three wire connection to the phones.

This was late 80's. I don't know what changed but it was always a pain in the butt to pull new wire, since you couldn't use the really cheap stuff.

[wblanford]

We had one of those at MIT called Dormline. We built it out of surplus switchgear from local CO's. It was always breaking down and needed a three wire connection to all the phones, but on the plus side you couldn't trace calls through it.

I also worked on those in the early '70 at MIT. I do not recall needing a three wire connection to the phones.

[DanKegel]

Three wire connection? Strange! I think ours (BTE, in Blacker House at Caltech) only needed two wires to each phone.

[jflorey2]

I helped maintain my dorm's electromechanical phone exchange back in the early '80's. It had 60 lines, and it was cool to watch the switches step as people dialled.

We had one of those at MIT called Dormline. We built it out of surplus switchgear from local CO's. It was always breaking down and needed a three wire connection to all the phones, but on the plus side you couldn't trace calls through it.

[DanKegel]

Sunking's really useful on battery questions, so people put up with his quirks.

To the question "do solar inverters emit an unsafe level of electromagnetic radiation", the answer is "no", I think, based on looking at sources like

http://www.who.int/peh-emf/publications/facts/fs322/en/

To the question "do solar inverters emit enough RF to interfere with with nearby radio and TV reception", the answer is "sometimes, maybe; if it happens, document it and add countermeasures like RF chokes".
The FCC puts limits on emissions, see http://www.edn.com/design/systems-de...ns-and-options for a wall of info about that from the designer's point of view. But problems can still occur, see e.g.
https://www.reddit.com/r/amateurradi...hey_gifted_me/
or
https://www.solarpaneltalk.com/forum...radio-stations
Avoiding interference probably depends on the installer adding RF chokes.

So, how well shielded are SolarEdge inverters? Here's a photo of one with the door open:
https://goo.gl/photos/aNJDinEASa5ssBMT7
I don't know if the outer case is shielded, it looks plastic, but there could be a conductive layer inside it. Still, that leaves the seams and exit ports for RF to leak out.
The silvery block near the top looks like a well-shielded section. I bet the high-power switching stuff is in there, and care was taken to prevent leakage.
The DC input and AC output wires exiting at the bottom have large RF chokes not mentioned in Solar Edge's documentation, so I bet they were added by the installer to reduce interference. (Good for him!)

I tested whether my SolarEdge inverter interfered with radio reception just now by walking around with a portable AM radio (Sony ICF-SW7600G).
Standing a few inches away from the inverter, I was still able to receive WWV at 15.00 MHz from several states away clearly.
And it didn't interfere with local stations like KFWB, either.
Now WWV's pretty powerful, but I'm in Los Angeles, and it's in Colorado, so if I can hear that clearly, things aren't so bad.
Turning the inverter off reduced the noise slightly, so there is a little interference, but so far it hasn't bothered me.
For comparison, even with the inverter off, just being near our gutter downspout caused far more interference - I guess the downspout acts like a big antenna.

But of course, inverters are only one possible source of RF energy; the optimizers could emit it, too, and I haven't tested that yet.
So can LED lights, CFL lights, computers, cordless phones, set-top boxes, video games, and basically everything that has an integrated circuit in it these days, which means everything that uses electricity.

As Madge said, "you're soaking in it!" https://www.youtube.com/watch?v=H7BvEldVEHU

[icebox]

Lmao - when I saw this. Icebox, some people are just effing jerks. Either they didn't get enough hugs when they were young, or might be tramatized because after drinking fresh milk from the cows they found out the family only had bulls. Ask all questions and some will give good answers, some will give opinions, some wok give wrong answers, and some will throw in extra crap free of charge - perhaps as a means to clense their soul of negativity they've cultivated for many many years. Just remember 30 years ago cigarettes were the in thing and they were not bad.

2 People, the first to reply to most threads, felt disheartened that somebody dare 'walk' into their imaginary kingdom and ask a question that is contrary to their beliefs.

They misunderstood the intent of my question anyway, foul is on them.

[MikeInRialto]

Did I insult you in any way?

Lmao - when I saw this. Icebox, some people are just effing jerks. Either they didn't get enough hugs when they were young, or might be tramatized because after drinking fresh milk from the cows they found out the family only had bulls. Ask all questions and some will give good answers, some will give opinions, some wok give wrong answers, and some will throw in extra crap free of charge - perhaps as a means to clense their soul of negativity they've cultivated for many many years. Just remember 30 years ago cigarettes were the in thing and they were not bad.

[bcroe]

All that Blue Box stuff was possible because of the way the mechanical system set up calls. A local switch would signal a
toll office with the required call destination, via tones similar to DTMF. The toll office would connect to another toll office
and repeat the process, continuing across the country till the call finally connected via a local switch. So you could send
your own tones and take over the call.

We cut over the first digital toll (4ESS) in Feb 1976, a day I'll not forget after 9 years of working on it. When the whole
continent was converted, all transmission became digital. Common Channel Interoffice Signaling carried the call setup instructions.
The control chose a path across the whole network, sent commands to all the offices involved, and you instantly had a
connection, no waiting, and no chance to interject your own control. Bruce Roe

[wblanford]

Spiro T Agnew - There was the Spiro, which generated the 2500 Hz tone and the touch tone key pad with the operator frequencies for making free long distance calls. The T was a bridge rectifier which could be inserted in series with the pay phone telephone line to return your money at the conclusion of the call. The Agnew was a box with a momentary switch, a series capacitor and battery. The Agnew was placed in series with your phone. When an incoming long distance call started ringing, the momentary switch briefly shorted the line. The capacitor provided audio coupling to the phone and the battery supplied power to the phone.