I have read a book on architecture that discussed various EM fields inside homes. One problem that was discussed was the use of single pole cord switches. Apparently, after the lamp is switched off, the EM field continues on the wire between the switch and the bulb.
Recently, I have searched for 2-pole cord switches and have not found any.
Anyone who plays guitar or has plugged an RCA plug into a HiFi has seen the problem!
However, the problem is much larger than just "cord switches"! Basically, a house is full of wires going to wall plugs and lighting fixtures. The wall plugs usually are always on, and the lighting fixtures are nearly as bad, given that the wires to the wall switch at least are also always on. Table lamps and the like have an even worse problem in that the cord is all over the floor and the "off" switch is up at the bulb. This leaves all that cord ready to radiate various fields.
The hum you hear in your guitar or when plugging a stereo signal line is electrostatic. Which is to say 120v AC is being fed to the wires in the walls which form one "plate" of a capacitor. If you happen to touch a signal like in a stereo, your finger is conductive to a degree and thus your whole body forms the other plate of the capacitor feeding 60 Hz into the sound gear. This capacitance is small, but the input voltage is high, and the stereo is amplifying with lots of gain.
Architecturally speaking, a friend of mine built his house correctly in this regard by having all AC lines switched in the basement centrally. HE uses low voltage lines to wall switches which just provide signal voltages to the remote switches controlling the AC power. This way when the switch is OFF there is no connection to the house wiring. However if you think that this means there are no EM problems you'd be wrong. He has these lights on a dimmer and when the kitchen fluorescent lights are on, the dimmer constantly adjusts itself!
As it turns out all manner of interference can go up and down house wires. And in his case if the various lights and plugs are ON, the wiring is no different from standard wiring. RF interference can go up and down the wires (which act as antennas) whether they are "on" or "off". Double pole switches can break up the wires in to shorter pieces which reduces pickup, but only if the switch is open.
As for cord switches, I'd expect a double pole one to do very little given that most of the hum comes from the wall wiring not to mention the big coil of cord on the floor behind the cord switch.
There are electric fields and there are magnetic fields. When current is flowing through a wire, these are linked (Through Maxwell's equations and Faraday's Laws).
When no current is flowing and there is a potential difference (voltage), as an extension cord with nothing plugged into the outlet end, there exists an electric field only. For several years now, low cost (AC) voltage detectors which can sense this field and tell you if a wire or outlet is energized, are available.
A double pole cord switch (if these exist) would theoretically isolate the energized section and minimize the (electric) field to zero or near zero.
That being said, electric and magnetic fields are all around you (depending on what country you live in at 50 or 60 Hz). They are in your bathroom, in your kitchen, near your computer monitor, and your electric heater/air conditioner. It is very difficult to isolate yourself from these low-level fields. If you live near any kind of overhead or underground power lines, you are most likely being bathed in a constant low level field that surrounds the lines. It has been this way since the late 19th century when the world became electrified.
A much larger issue of potential concern is near universal spread of cellular phones (and their associated towers). These are 'always on' in a sense, and operate in the same general band that your microwave oven operates (although at much, much lower power).
Yes, I'm aware of that. The book -Prescriptions for a Healthy House by Paula Baker-LaPorte -has a chapter (16) on electricals. I was under the impression that the two adjacent hot-neutral wires pretty much cancelled out the fields, except very close to the wires. So if the switch is at the end, just under the bulb, both wires have the same length and again, except very close to the wires the EMF should be small. Or did I get this wrong?.
Wow! The player becomes electrical too :-( When I buy a guitar, it will be acoustic :-)
That's a neat idea. It seems to me that Health Departments have kept out of this field for far too long. I hate the thought of going back to incandescent lamps and roll on LED lights.
That makes good wiring a very tricky process.
An electrician once wired a house for me and he pulled the wires to tight through the studs etc that I often had trouble installing the outlets. Did he know something that I didn't?
So, instead of looking for a 2-pole cord switch (Pass and Seymore don't make them) if I just replace the lamp holder with one that has a switch, it won't help much?