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Home > Archive > Electrical Engineering > May 2007 > 2-pole cord switches?
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2-pole cord switches?
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| Red Fox 2007-05-08, 3:25 am |
| Hi Experts,
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.
Comments appreciated.
RF
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Red Fox wrote:
> Hi Experts,
> 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.
>
> Comments appreciated.
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.
Benj
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| Beachcomber 2007-05-08, 3:25 am |
| On Tue, 08 May 2007 04:34:08 GMT, "Red Fox" <RedFox@NoDen.Con> wrote:
>Hi Experts,
>
>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.
>
>Comments appreciated.
>
>RF
>
>
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).
Beachcomber
| |
| Red Fox 2007-05-09, 8:25 pm |
|
"Benj" <bjacoby@iwaynet.net> wrote in message
news:1178607136.684906.171660@h2g2000hsg.googlegroups.com...
>
> Red Fox wrote:
inside[color=darkred]
the[color=darkred]
any.[color=darkred]
Thank you Benj for the great reply.
[color=darkred]
> 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.
>
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?.
> 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.
Wow! The player becomes electrical too :-(
When I buy a guitar, it will be acoustic :-)
> 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!
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.
> 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.
That makes good wiring a very tricky process.
> 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.
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?
> Benj
Thank you again for your time and effort.
RF
| |
| Red Fox 2007-05-09, 8:25 pm |
| "Beachcomber" <invalid@notreal.none> wrote in message
news:46401bab.14438312@news.verizon.net...
> On Tue, 08 May 2007 04:34:08 GMT, "Red Fox" <RedFox@NoDen.Con> wrote:
>
inside[color=darkred]
any.[color=darkred]
Thanks Beachcomber for your advice, and for taking time off the beach ;-)
[color=darkred]
> 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).
Yup, I'm an M.E. and had courses in that area.
> 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.
I know that the E and M are separate fields and one can exist without the
other.
From what I can remember, the magnetic fields more unhealthy because of the
greater difficulty in shielding.
> 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.
That's interesting because I have a couple of AC meters and hadn't thought
of that. The book -Prescriptions for a Healthy House by Paula
aker-LaPorte -has a chapter (16) on electricals and there quite a few
devices are listed, including a gaussmeter. Are the AC meters you mention
used for measuring the flow in the circuits or have they some capability to
detect the fields?
> the energized section and minimize the (electric) field to zero or
> near zero.
I can't find one and have decided to replace the bulb holder with one that
has a built-in switch.
I'm hoping that will help.
> 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.
For the benefit of our health, maybe we should have stayed with candles or
oil lamps, but then they both have their own pollution. Is there any way to
win? - maybe totally solar - electric with low voltage LED systems and
putting microwave ovens, etc. in lead lined closets :-)
> 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
Indeed yes. There was a big splash in the British newspaper The Independent
about cell phones destroying bees and brains. When a cell phone is placed
near a hive, the bees don't go home. Below is a small extract about human
brains.
Thank you for your great post.
RF
____________________________________________________________________
The case against handsets
Evidence of dangers to people from mobile phones is increasing. But proof is
still lacking, largely because many of the biggest perils, such as cancer,
take decades to show up.
Most research on cancer has so far proved inconclusive. But an official
Finnish study found that people who used the phones for more than 10 years
were 40 per cent more likely to get a brain tumour on the same side as they
held the handset.
Equally alarming, blue-chip Swedish research revealed that radiation from
mobile phones killed off brain cells, suggesting that today's teenagers
could go senile in the prime of their lives.
Studies in India and the US have raised the possibility that men who use
mobile phones heavily have reduced sperm counts. And, more prosaically,
doctors have identified the condition of "text thumb", a form of RSI from
constant texting.
Professor Sir William Stewart, who has headed two official inquiries, warned
that children under eight should not use mobiles and made a series of safety
recommendations, largely ignored by ministers.
> Beachcomber
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