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Author Topic: Phone line crackles  (Read 3574 times)

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Offline phone_guy

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Phone line crackles
« on: May 11, 2014, 05:02:45 PM »
Hi, basically I am a new user (end user) who is just curious about how phones work, and couldn't really find the answer to my question anywhere.

Basically, I read that bad wiring (eg, corroded wires or something) can cause phone crackles, and I can't figure out why.  I know the phone line carries your voice from the house to the phone company's connection, but if there is a corroded wire...  I can't figure out why that would cause crackling in the line.  If you could answer my question I would greatly appreciate it.  Thanks!

Online MacGyver

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Re: Phone line crackles
« Reply #1 on: May 11, 2014, 07:27:29 PM »
Hi phone_guy,

Welcome to the board.  Sorry for the slow replies, but most techs lie low on the weekend when they can get away with it.

Being an end user I'm not sure how technical of an answer you want, so without getting into impedence issues, ground loops, and other things you likely care nothing about, think of your incoming line as having two wires.  Just like the wires on your desk lamp, they are insulated from each other, and if you've been in a situation where someone accidently touched those two wires together, you likely saw a spark and heard a loud pop which came from the electricity arcing.  

Your phone wires use a much lower voltage, but the same principle applies.  Now if there are splices in the wires that aren't water tight, if the insulation on those wires is dry and cracking, or if ants have built their mounds up into the connection boxes, then you can have some shorting out across those two wires due to rain, moisture or even a dead rat in the box.  Now consider those two wires being twisted around each other with cracks in the insulation, and buried in wet ground.  You can see how you might get some shorting between them.

This is a very simple explanation and like most things, the deeper you get into it the more complicated it becomes, but maybe this will give you a starting point.  If there are some specifics you'd like to know, there are some old time Bell guys around here who have likley forgotten more on the subject than the rest of us even knew.
-I'm only here because my flux capacitor is broken.

Offline Marc Haycook

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  • Location: Jefferson City, MO
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Re: Phone line crackles
« Reply #2 on: May 12, 2014, 10:40:47 AM »
I will add to what MacGyver said by saying you can isolate the problem to either internal (house) wiring or a problem that the telephone company will need to fix. You should have a box on the side of your house called a NID. This is where the phone company connects their wires to yours and it provides a point to test the line.

Just open the box and plug your phone into the test jack. If the line is clear then the problem is in your wiring. If you can still hear the noise, then the problem is further down the line and you'll need to contact your service provider.

The NID should look like the image below and you will likely need a screw driver to open your access.

Marc Haycook
CCNA
Sport-Touring

Offline phone_guy

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  • Posts: 2
Re: Phone line crackles
« Reply #3 on: May 12, 2014, 11:45:40 AM »
Hi phone_guy,

Welcome to the board.  Sorry for the slow replies, but most techs lie low on the weekend when they can get away with it.

Being an end user I'm not sure how technical of an answer you want, so without getting into impedence issues, ground loops, and other things you likely care nothing about, think of your incoming line as having two wires.  Just like the wires on your desk lamp, they are insulated from each other, and if you've been in a situation where someone accidently touched those two wires together, you likely saw a spark and heard a loud pop which came from the electricity arcing.  

Your phone wires use a much lower voltage, but the same principle applies.  Now if there are splices in the wires that aren't water tight, if the insulation on those wires is dry and cracking, or if ants have built their mounds up into the connection boxes, then you can have some shorting out across those two wires due to rain, moisture or even a dead rat in the box.  Now consider those two wires being twisted around each other with cracks in the insulation, and buried in wet ground.  You can see how you might get some shorting between them.

This is a very simple explanation and like most things, the deeper you get into it the more complicated it becomes, but maybe this will give you a starting point.  If there are some specifics you'd like to know, there are some old time Bell guys around here who have likley forgotten more on the subject than the rest of us even knew.

So basically what you're hearing is the sound of the short circuit when you hear the crackling?

Online silversam

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  • Location: NYC
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Re: Phone line crackles
« Reply #4 on: May 12, 2014, 01:13:37 PM »
Basically, Yes.

Not a dead (complete) short, but certainly an intermittent one.

Sam