Telephone Line, Red Wire, Ringing Voltage to Ground

Hi,

I have used a Fluke DMM with a Max/Min capture feature to measure the
ringing voltage, not only red to green, but also red to ground (and green to
ground).

To my surprise, the red wire to ground ringing voltage (some telephone
equipment on line) was 93.2 VAC !! The green wire to ground ringing voltage
was 36.4VAC. Note: Telephones are ringing.

Is this normal?

Thank You in advance, John

 

[pfjw@aol.com]

https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

The internet is your friend.

Peter Wieck
Melrose Park, PA

 

[Fox's Mercantile]

On 1/20/20 11:34 AM, pfjw@aol.com wrote:

https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

The internet is your friend.

Peter Wieck
Melrose Park, PA

Wonderful explanation.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

On Mon, 20 Jan 2020 09:34:17 -0800 (PST), "pfjw@aol.com"
<peterwieck33@gmail.com> wrote:

https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

The internet is your friend.

Peter Wieck
Melrose Park, PA

Hi, I saw that "sandman", and other places on the web, but it did NOT say
anything about the ringing voltages from red to ground or green to ground.

That is why I made this post.

John

 

[pfjw@aol.com]

On Tuesday, January 21, 2020 at 7:26:22 AM UTC-5, jaugu...@verizon.net

Hi, I saw that "sandman", and other places on the web, but it did NOT say
anything about the ringing voltages from red to ground or green to ground..

That is why I made this post.

a) Most POTS phones are two-wire these days.
b) In most cases, the ground (separate) does not leave the demarc.
c) Both the the "red" and the "green" are not at ground potential, *and* also not at the same potential to each other.

Therefore the 'ring voltage' will be different from each to ground than between the POTS conductors. Which was covered in the article linked, but not with these same words. Read carefully the section on measuring AC over DC, and that should help you understand.

Peter Wieck
Melrose Park, PA

 

[jfeng@my-deja.com]

Try putting a 1K resistor in parallel with the meter. I predict that you will get something close to zero for both wires to your earth ground for both ac and dc measurements.

 

[Tim R]

On Monday, January 20, 2020 at 1:15:44 PM UTC-5, Fox's Mercantile wrote:

On 1/20/20 11:34 AM, pfjw@aol.com wrote:
https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

The internet is your friend.

Peter Wieck
Melrose Park, PA


Wonderful explanation.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

And it contained this little gem, which you all probably knew, but was a surprise to me:

*****
A very good technical explanation for variances in AC voltage measurements was put out by Agilent
(formerly HP), who makes their own meters ranging from handhelds to lab equipment. I was amazed to read that meter manufacturers calculate True RMS by reading the heat produced by the AC voltage (4 page PDF file):
*****

I could not get to the Agilent PDF just now.

 

[Michael Terrell]

On Thursday, January 23, 2020 at 1:57:31 PM UTC-5, Tim R wrote:

On Monday, January 20, 2020 at 1:15:44 PM UTC-5, Fox's Mercantile wrote:
On 1/20/20 11:34 AM, pfjw@aol.com wrote:
https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

The internet is your friend.

Peter Wieck
Melrose Park, PA


Wonderful explanation.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

And it contained this little gem, which you all probably knew, but was a surprise to me:

*****
A very good technical explanation for variances in AC voltage measurements was put out by Agilent
(formerly HP), who makes their own meters ranging from handhelds to lab equipment. I was amazed to read that meter manufacturers calculate True RMS by reading the heat produced by the AC voltage (4 page PDF file):
*****

I could not get to the Agilent PDF just now.

There are ICs that calculate RMS for test equipment.

Agilent changed their name to Keysight several years ago.