Measuring impedance of wall socket

On Fri, 29 Jul 2005 16:30:45 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wroth:

I did it with a butter knife across the blades of a plug. My son found
a brass ball at the end of a pull chain fit nicely into an empty light
socket (and made a nice sizzling and sparking, which left some welts
on his leg). Do girls do stuff like that?


Best regards,
Spehro Pefhany

I knew a girl once who sizzled when she sparked. She never left welts
on my leg but I did get some scratches on my back.

Jim

 

[keith]

On Fri, 29 Jul 2005 13:32:12 -0700, Joel Kolstad wrote:

"Keith Williams" <krw@att.bizzzz> wrote in message
news:MPG.1d5457f27d08d2d989b4b@news.individual.net...
Refrigerators are not supposed to be on GFCIs (there is an exemption
for them).

Do you happen to know why not?

For exactly the reasons above. False trips are more costly than any
safety offered. AIUI, the outlet must be single-use and behind the unit
(so it's not a tempting target for a weed-whacker).

--
Keith

 

[keith]

On Fri, 29 Jul 2005 20:56:28 +0000, Michael A. Terrell wrote:

Jim Thompson wrote:

My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

...Jim Thompson


I'll bet you didn't have to tell him not to do that again! ;-)

He's lucky he had the opportunity!

--
Keith

 

[Carl D. Smith]

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
<thegreatone@example.com> wrote:

My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

This reminded me of something. I didn't witness it, but my aunt
once told a story about when her son, at maybe the age of three,
managed to unplug the phone cord from the phone, and stuck the
end in his mouth. She noticed this about a millisecond before
the phone rang, at which point she said he "went ballistic."

 

[Carl D. Smith]

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
<thegreatone@example.com> wrote:

My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

 

[Jim Thompson]

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
<cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.

I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jeff]

"Jim Thompson" <thegreatone@example.com> wrote in message
news:754ne11468qsd08p7ugt7rvenm04puuaj4@4ax.com...

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.


I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

I was always taking things apart when I was a kid, still do sometimes just
to take a peak...

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Pooh Bear]

Jim Thompson wrote:

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.


I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

...Jim Thompson

It's the putting it back together that's tricky isn't it ?

Graham

 

[John Larkin]

On Sat, 30 Jul 2005 15:55:14 GMT, "Jeff" <antispam@hotmail.com> wrote:

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)




I was always taking things apart when I was a kid, still do sometimes just
to take a peak...

Some serious fraction of the gadgets I buy have to be re-engineered
some before they work at all!

John

 

[Michael A. Terrell]

Pooh Bear wrote:

It's the putting it back together that's tricky isn't it ?

Graham

That was why I took apart dead radios and TV sets, then sold the ones
I fixed. After that, I was working in a TV shop at 13 after school and
Saturdays.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida

 

[Jim Thompson]

On Sat, 30 Jul 2005 17:10:45 +0100, Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote:

Jim Thompson wrote:

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.


I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

...Jim Thompson

It's the putting it back together that's tricky isn't it ?

Graham

That's where I got myself into trouble, taking apart spinning wheels,
pedal-type sewing machines, and wind-up clocks ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Pooh Bear]

Jim Thompson wrote:

On Sat, 30 Jul 2005 17:10:45 +0100, Pooh Bear
rabbitsfriendsandrelations@hotmail.com> wrote:


Jim Thompson wrote:

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.


I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

...Jim Thompson

It's the putting it back together that's tricky isn't it ?

Graham

That's where I got myself into trouble, taking apart spinning wheels,
pedal-type sewing machines, and wind-up clocks ;-)

...Jim Thompson

I'm told that at the age of 3 ( too young for me to remember this one ) I
managed to dismantle a railway carriage lock on the return jouney from
London. My parents found themselves trapped and had to call for assistance !

Graham

 

[keith]

On Sat, 30 Jul 2005 16:54:52 -0700, Jim Thompson wrote:

On Sat, 30 Jul 2005 17:10:45 +0100, Pooh Bear
rabbitsfriendsandrelations@hotmail.com> wrote:


Jim Thompson wrote:

On Sat, 30 Jul 2005 05:22:56 GMT, Carl D. Smith
cdsmith69NOSPAM@earthlink.net> wrote:

On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

Another thought...

Is he an engineer now?

Big software guru in networks.


I often wonder which is the cause and which is the effect. When
electrical engineers tell stories of doing things like this when
they were a kid, I wonder if they did it because they already had
some engineer in them, or if that was the event that turned them
into an engineer...

Good question. I was always taking things apart when I was a kid, got
in a lot of trouble over that ;-)

...Jim Thompson

It's the putting it back together that's tricky isn't it ?

Graham

That's where I got myself into trouble, taking apart spinning wheels,
pedal-type sewing machines, and wind-up clocks ;-)

As did I. My father (an EE Prof) didn't take too kindly to me not being
able to put back together his typewriter, when I was six. His cow-orkers
told him that he should treat me as a son, not a grandson. I tagged
along with him whenever possible (until he died, forty years ago).

--
Keith

 

[legg]

On Fri, 29 Jul 2005 00:46:43 -0700, "cyrille perron"
<cyrille.perron@sympatico.ca> wrote:

Hi, I'm not sure this is the best forum to post this question in but I was
wondering how one would go about measuring the impedance of a wall socket?
(Strange question, I know) I have some general ideas but would like to
confirm my thinking. Any websites or other resources explaining the
general concept would be greatly appreciated. Much thanks in advance.

One method, pertinent at 500KHz and up;

"Technique for Measurement of Powerline Impedances in the Frequency
Range from 500 kHz to 500 MHz"
Kwasniok, Bui, Koslowski, Stuchly.
IEEE trans Electromagnetic Compatibility V35 #1 p87-89 Feb'93

Their rough results show peaks and dips between 10 and 1000 ohms over
the band - Peaks at 2 and 20 MHz, dips at 4MHz.

You could use a safely-coupled/limited/filtered spectrum analyser to
generate this data, outside of the powerline frequency, as with any
two-wire network. An HP 3577 used for this shows a range of impedances
between 10 and 500 ohms.

At the line frequency, a rough idea can be obtained by monitoring
voltage distortion (as delta V) vs current drawn (delta I) for any
power component with a capacitive input rectifier.

RL

 

[ehsjr]

Ben Bradley wrote:

I've done this at my last two jobs, but the measurement was made at the service entrance,
and not at some wall socket. Both times, the result was about 1/10 ohm (in the US, at 120
volts). This is at 60 Hz. Rene suggests that by asking for "impedance", the OP wanted to
know the result over a band of frequencies. I didn't have the equipment for such a
measurement, but I did find a paper where someone had done it. The result was a wildly
varying impedance vs frequency.


I worked with X-10-type controls a while back. and I recall hearing
that "the" line impedance at 120kHz was 6 ohms. I never tested this
myself, but in retrospect, I (actually the guy who was designing the
hardware) should have.

Time out, to think about this. How could there be a
single value? Different sizes and lengths of conductors
can exist from circuit to circuit, and different loads could
be connected on any given circuit or from circuit to circuit.
The circuits can be wired with NM, or AC or in conduit, etc.
Each junction causes an impedance bump, and the number of
junctions as well as their physical layout varies. Attached
equipment could have LC line filters or be purely resistive.


I think the question has to be crisply defined to get a
definitive answer.

Ed

You may find more info on power line impedance by researching power
line carrier (PLC).



John


-----
http://www.mindspring.com/~benbradley

 

[The Real Andy]

On Fri, 29 Jul 2005 00:46:43 -0700, "cyrille perron"
<cyrille.perron@sympatico.ca> wrote:

Hi, I'm not sure this is the best forum to post this question in but I was
wondering how one would go about measuring the impedance of a wall socket?
(Strange question, I know) I have some general ideas but would like to
confirm my thinking. Any websites or other resources explaining the
general concept would be greatly appreciated. Much thanks in advance.

I have this problem you see. My wife kicked me out of the garage, and
now i have to work in the garden shed. The only problem is that I dont
have a rubbish bin, so my shed is slowly being impeded by beer
bottles. So therefore the impedance of your wall socket is determined
by how mauch beer you drink and how often you clean out the shed. What
the fuck is a wall socket? Is that one of them things you plug the
vacuum cleaner in, or is the tv antenna socket thing. I even have a
wall socket in my joint that you canplug a gas heater in....BURP...

 

[Ben Bradley]

On Sun, 31 Jul 2005 05:17:41 GMT, ehsjr <ehsjr@bellatlantic.net>
wrote:

Ben Bradley wrote:

I worked with X-10-type controls a while back. and I recall hearing
that "the" line impedance at 120kHz was 6 ohms. I never tested this
myself, but in retrospect, I (actually the guy who was designing the
hardware) should have.

Time out, to think about this. How could there be a
single value? Different sizes and lengths of conductors
can exist from circuit to circuit, and different loads could
be connected on any given circuit or from circuit to circuit.
The circuits can be wired with NM, or AC or in conduit, etc.
Each junction causes an impedance bump, and the number of
junctions as well as their physical layout varies. Attached
equipment could have LC line filters or be purely resistive.


I think the question has to be crisply defined to get a
definitive answer.

I agree, which is why I put the word "the" in quotes. The 6 ohms is
a very rough, average, ballpark number, I have no doubt it can and
does vary a lot.

Ed



You may find more info on power line impedance by researching power
line carrier (PLC).

-----
http://www.mindspring.com/~benbradley

 

[Andy]

Andy writes:

The impedance depends on the frequency, and I don't know your
application.

Back in college I designed a number of carrier current transmitters
that put the local college AM station directly into the power line.
That
was a bitch. At 500 khz there are a LOT of random variables....

Lots of wireless intercoms use the power lines inside a house for
coupling, and the line impedance is important at the frequency of
interest, which is high enough to be considered RF ........

If you are only worrying about the 60 hz line impedance, you will
have less of a problem (grin).

So you see, the application dictates what the answer will be.

You will get plenty of answers here for the 60 hz measurement.


Andy

 

[Don Lancaster]

cyrille perron wrote:

Hi, I'm not sure this is the best forum to post this question in but I was
wondering how one would go about measuring the impedance of a wall socket?
(Strange question, I know) I have some general ideas but would like to
confirm my thinking. Any websites or other resources explaining the
general concept would be greatly appreciated. Much thanks in advance.


That would depend entirely on what equipment was plugged in nearby.

Older daisywheel printers could take out X-10 systems for hundreds of feet.

Line impedance also, of course, is highly frequency dependent.

The neighborhood transformer arrangement would also be a factor.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Don Lancaster]

Ben Bradley wrote:

On Fri, 29 Jul 2005 12:40:06 -0700, The Phantom <phantom@aol.com
wrote:


On Fri, 29 Jul 2005 11:55:33 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


On Fri, 29 Jul 2005 09:40:52 -0700, Jim Thompson
thegreatone@example.com> wrote:


On Fri, 29 Jul 2005 08:05:55 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


On Fri, 29 Jul 2005 00:46:43 -0700, "cyrille perron"
cyrille.perron@sympatico.ca> wrote:


Hi, I'm not sure this is the best forum to post this question in but I was
wondering how one would go about measuring the impedance of a wall socket?
(Strange question, I know) I have some general ideas but would like to
confirm my thinking. Any websites or other resources explaining the
general concept would be greatly appreciated. Much thanks in advance.



Poke your dvm probes into one side of an outlet, and plug a toaster or
similar big resistive load into the other. Measure how much the
voltage droops when you fire up the toaster.

Impedance is pretty much droop_volts/load_amps.

John

My oldest son, when he was like 3 years old, did the impedance test
using a bobby pin ;-)

...Jim Thompson


Hey, everybody do this measurement and report what you get. The
toaster thing, not the bobby pin.

I've done this at my last two jobs, but the measurement was made at the service entrance,
and not at some wall socket. Both times, the result was about 1/10 ohm (in the US, at 120
volts). This is at 60 Hz. Rene suggests that by asking for "impedance", the OP wanted to
know the result over a band of frequencies. I didn't have the equipment for such a
measurement, but I did find a paper where someone had done it. The result was a wildly
varying impedance vs frequency.


I worked with X-10-type controls a while back. and I recall hearing
that "the" line impedance at 120kHz was 6 ohms. I never tested this
myself, but in retrospect, I (actually the guy who was designing the
hardware) should have.
You may find more info on power line impedance by researching power
line carrier (PLC).



John


-----
http://www.mindspring.com/~benbradley

Any decent line filter on any old printer or whatever will totally trash
the line impedance at 120 kHz.

Assume it is zero.


--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com