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eHam Forums => Elmers => Topic started by: KD2CJJ on April 21, 2013, 12:32:21 PM



Title: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 21, 2013, 12:32:21 PM
Elmers,

I have had this very annoying thing now since buying my first radio.  When I turn off or on a light source, etc. in my house I get a blip on my radio (I see the S meter go to like 10+) the agc kicks in then it quiets down then comes back up.... Its the same exact symptom if there is lighting in the area.  What really annoys me is when I start to rotate my antenna left or right I get the exact same symptom pressing then releasing the buttons.  I have two different antenna's same issue, 3 different radios, same issue.  Its almost like there is a micro surge, EMP or some noise in the electrical wiring when turing on or off anything in my house.

I have all my equipment plugged into a monster power strip with noise filters, I have even tried putting it into my TripLite UPS which has noise filters and Auto Voltage Circuit - that didn't help (unless of course I unplug it from the wall).

So, I suspect its more of a EMP in my house traveling over my electrical wiring?? 

Elmers... I am stumped!

Thanks
Mike
KD2CJJ


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: AC5UP on April 21, 2013, 01:46:15 PM
Unplug the antenna from the radio. Do you still hear blips when something is turned on or off?

If you do the power supply may have poor filtering or a touch of overshoot when the AC voltage changes, but I'm going to guess the blips go away. That's because something common to all three antennas is near enough to house wiring, street wiring, or a drop transformer that it can read the mail on your AC power service Q-5. Also possible your feedline has some shielding issues. Ladder line or coax?

A little tweak & listen could be the fix, starting with whatever might be common to everything. (?)


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 21, 2013, 03:00:43 PM

OK.. I did the test... and yes after unplugging the antennas (putting the switch to center) the issue went away!

So what your telling me is there is some small EMP coming off my electrical into the antenna?  Do you have any recommendation to stop this?

Unplug the antenna from the radio. Do you still hear blips when something is turned on or off?

If you do the power supply may have poor filtering or a touch of overshoot when the AC voltage changes, but I'm going to guess the blips go away. That's because something common to all three antennas is near enough to house wiring, street wiring, or a drop transformer that it can read the mail on your AC power service Q-5. Also possible your feedline has some shielding issues. Ladder line or coax?

A little tweak & listen could be the fix, starting with whatever might be common to everything. (?)


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K0IZ on April 21, 2013, 03:21:25 PM
What does "putting the switch to center" mean?


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 21, 2013, 03:28:10 PM
Setting the position of my antenna switch to ground..
What does "putting the switch to center" mean?


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: VA7CPC on April 21, 2013, 05:33:04 PM
If you don't have a balun at the feedpoint of your antenna, try adding one. 

If you don't have a blun at the rig-to-coax connection, try adding one.  Or put a few ferrite chokes around the coax, where. it plugs into the rig

If the _whole coax_ is acting as an antenna,  that might fix the problem.  Your rig _should_ be insensitive to common-mode noise, but that doesn't mean it _is_ insensitive.

.            Charles


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 21, 2013, 05:44:39 PM
Mike:

From what you describe, it isn't a radio problem.  Or, an antenna problem.  Your radios are, via your antennas, likely picking up broadband noise from an electrical arc of some sort.  It may be a bit of a challenge, but, I think I can help you.

You will need to do a few tests for me.....with antennas connected.

You said that whenever you turn anything on, a spike occurs.  Are the things you are talking about primarily lights, small appliances, etc?  All of them being 120V, as I suspect, involve increases in current through one or possibly two hot legs and your neutral conductor.

The first test you will need to do is have someone turn only 240 volt appliances on and off to see if the zap still occurs.  An electric clothes dryer or an electric range oven, or your air conditioning condenser unit.  Do this while you are listening.  Does the zap still happen?

If it does, one of the two hot leg incoming service wires is probably damaged, or one of the main lugs on your panel is likely loose.

 If it does not occur when you switch only 240 volt appliances on and off, it is likely a loose main neutral lug in your main panel or a broken or damaged neutral on the utility service drop to your home.  You may also want to use a good RMS voltmeter and see if both 120V hot legs are balanced.  Another symptom of a damaged or open neutral is unbalanced low or high voltage from hot leg to neutral.



Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W0BTU on April 21, 2013, 06:22:42 PM
What kind of antennas do you have, and how close are they to your house?

And what band(s) does this happen on?


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K8AXW on April 21, 2013, 06:35:15 PM
Whenever any electrical circuit in the house is opened, like turning off a light, the switch contacts creates an arc.  This arc is the same as the old time "spark" transmitters.  It's basically a radio wave.

Closing a switch can do the same but is not as prevalent.  The only time this doesn't happen is when the AC cycle is crossing the "zero" point.  I mention this because you can open and close a switch several times and it won't create a spark every time.

Since this is happening with two antennas and three radios the only common thing is your house wiring.  I'm wondering if your house has been wired with aluminum wire?  Is the entrance panel adequately grounded with outside ground rods?  

Does this happen with any switch or load in the house?  If it's confined to say, one or two switches that get operated quite a bit, it's possible that these switches need to be replaced.  A switch that has contacts that are dragging because of surface erosion, corroded pivot points, etc. will cause a longer make/break time which promotes spark formation.

It would be interesting to monitor your AC with an O'scope while switches are opened and closed throughout the house.  



Al - K8AXW


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 21, 2013, 06:50:37 PM

OK.. I did the test... and yes after unplugging the antennas (putting the switch to center) the issue went away!

So what your telling me is there is some small EMP coming off my electrical into the antenna?  Do you have any recommendation to stop this?

The receiver did not respond to the arc with antennas disconnected according to what Mike said.  His antennas are picking up the arcing.

He said that if anything electrical (presumably 120v) is operated in his home, including his rotor, it produces the arc/zap.

It isn't an antenna problem, and most likely not a single switch due to the involvement of many 120volt loads and several diverse sections of his AC branch circuit wiring.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 21, 2013, 08:55:09 PM

Yes I originally i thought it was coming via the electrical socket but in fact it is coming via the antenna since if I disconnect the antenna the issue doesn't surface.

My house is fully wired with copper latest standards..

I talked to my dad today who is also a ham and he also experiences this but generally only if he turns on his fluorescent  lights.

Now hear this..I can turn on devices like my pc on the same circuit and I don't have the issue...it truly is related to the micro arc giving off a radio signal...

Any other opinions on how I can combat this?


OK.. I did the test... and yes after unplugging the antennas (putting the switch to center) the issue went away!

So what your telling me is there is some small EMP coming off my electrical into the antenna?  Do you have any recommendation to stop this?

The receiver did not respond to the arc with antennas disconnected according to what Mike said.  His antennas are picking up the arcing.

He said that if anything electrical (presumably 120v) is operated in his home, including his rotor, it produces the arc/zap.

It isn't an antenna problem, and most likely not a single switch due to the involvement of many 120volt loads and several diverse sections of his AC branch circuit wiring.



Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: ZS5WC on April 21, 2013, 11:35:25 PM
 :) Switch on the rig noise blanker (NB) , make sure the levels are set correctly.
The NB is designed to remove inpulse noise exactly as you are describing.
The pickup of local noise is entirely normal, but the NB should remove it.

73


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on April 22, 2013, 04:16:43 AM
Check your grounding system and its connections including the shack grounds and the interconnection to the electrical ground.  Even with a dipole, the ground is still a part of the antenna, and yours may be troublesome.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 22, 2013, 06:03:18 AM

Yes I originally i thought it was coming via the electrical socket but in fact it is coming via the antenna since if I disconnect the antenna the issue doesn't surface.

My house is fully wired with copper latest standards..

I talked to my dad today who is also a ham and he also experiences this but generally only if he turns on his fluorescent  lights.

Now hear this..I can turn on devices like my pc on the same circuit and I don't have the issue...it truly is related to the micro arc giving off a radio signal...

Any other opinions on how I can combat this?


OK.. I did the test... and yes after unplugging the antennas (putting the switch to center) the issue went away!

So what your telling me is there is some small EMP coming off my electrical into the antenna?  Do you have any recommendation to stop this?

The receiver did not respond to the arc with antennas disconnected according to what Mike said.  His antennas are picking up the arcing.

He said that if anything electrical (presumably 120v) is operated in his home, including his rotor, it produces the arc/zap.

It isn't an antenna problem, and most likely not a single switch due to the involvement of many 120volt loads and several diverse sections of his AC branch circuit wiring.

Now saying that your PC does not produce the "pop" in your receiver is not quite what you first implied: that everything was producing the arcing when switched on.  So, if only some appliances or switches do, it sounds even more like a neutral problem.  Try the 240 volt appliances and see if they produce the noise.  Open or damaged neutral connections are safety hazards and can have disastrous consequences.   Best to find the problem now before something really serious occurs.
73,
Lee


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KE3WD on April 22, 2013, 06:07:03 AM
**Is the Antenna System grounded to a separate Ground Rod that is perhaps not bonded to the main electrical panel Ground?** (http://**Is the Antenna System grounded to a separate Ground Rod that is perhaps not bonded to the main electrical panel Ground?**)




Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K4RVN on April 22, 2013, 06:31:39 AM
Mike,
If after trying all the other advice you get and the problem is still there, buy you a MFJ-915 RF Isolator from someone like Giga parts, DX engineering, HRO, or others.  Connect the isolator to your transceiver via a short coax and the other end to your antenna.  The mounting instructions come with the 915. Good luck, keep us posted on the solution.

Frank


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 22, 2013, 06:27:24 PM
Mike:

I recently retired from doing forensic investigations.  Most were examination of fire scenes of suspicious cause and origin.  Those where an electrical source was suspected.  What you describe is most likely the RF spectrum of an electrical arc that is creating broad bandwidth noise.  Enough energy that your antennas and receivers pick it up.

You at first said or strongly implied that any switching of AC loads in your home caused the burst.  But, your last post indicated that when you turn your PC on, no arc burst was created.  Assuming that is a normal desktop PC with a switching power supply built in, that says something.  Since there are apparently sections of your home wiring branch circuits that don't produce the arc/zap, then the problem is most probably on one of your branch circuits from your electrical panel.  It could be a wire nut splice or possibly a screw terminal on a switch or outlet.  It could be either along the white or neutral wire or the black wire.

I'd recommend that you call in an electrician to assist you in locating and repairing the problem.  But, you could assist him and determine which circuit breaker supplies the circuit with the problem.  Once you find switches or appliances that generate the arc, trip the circuit breakers until you find the one that supplies power to the circuit with the problem.  The electrician can then begin inspecting the junction boxes to find the problem before it could cause a fire.

Several fires I investigated were caused by wire nut splices that either weren't tightened properly or the wires were not inserted far enough in them to make good electrical contact.  What happens in that case is a progressively higher resistance connection and elevated temperature while under load.  Serious stuff.   


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 22, 2013, 07:12:15 PM
My station ground is not the best being in the second floor of my house.  Everything is grounded to my water pipe.  So it could be a contributor... I will try putting a balun at the rig as I have an extra balun (guanella balun).   I just upgraded my rig and noticed its not as frequent but still there.

My neutral and ground are separate and distinct.  There is no stray voltage on the ground or neutral either.

I will report back on the balun.

Mike,
If after trying all the other advice you get and the problem is still there, buy you a MFJ-915 RF Isolator from someone like Giga parts, DX engineering, HRO, or others.  Connect the isolator to your transceiver via a short coax and the other end to your antenna.  The mounting instructions come with the 915. Good luck, keep us posted on the solution.

Frank


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 22, 2013, 07:20:58 PM

The pc and light switch on in the same circuit that I am complaining about.  What's weird is when I went to test it tonight of course I could not reproduce the issue! Even with my rotor controller!!

I'm wondering if there is a device that is plugged in that is amplifying the signal on the circuit or whole house which is now NOT plugged in and why it's not surfacing.

I'm still searching.


Mike:

I recently retired from doing forensic investigations.  Most were examination of fire scenes of suspicious cause and origin.  Those where an electrical source was suspected.  What you describe is most likely the RF spectrum of an electrical arc that is creating broad bandwidth noise.  Enough energy that your antennas and receivers pick it up.

You at first said or strongly implied that any switching of AC loads in your home caused the burst.  But, your last post indicated that when you turn your PC on, no arc burst was created.  Assuming that is a normal desktop PC with a switching power supply built in, that says something.  Since there are apparently sections of your home wiring branch circuits that don't produce the arc/zap, then the problem is most probably on one of your branch circuits from your electrical panel.  It could be a wire nut splice or possibly a screw terminal on a switch or outlet.  It could be either along the white or neutral wire or the black wire.

I'd recommend that you call in an electrician to assist you in locating and repairing the problem.  But, you could assist him and determine which circuit breaker supplies the circuit with the problem.  Once you find switches or appliances that generate the arc, trip the circuit breakers until you find the one that supplies power to the circuit with the problem.  The electrician can then begin inspecting the junction boxes to find the problem before it could cause a fire.

Several fires I investigated were caused by wire nut splices that either weren't tightened properly or the wires were not inserted far enough in them to make good electrical contact.  What happens in that case is a progressively higher resistance connection and elevated temperature while under load.  Serious stuff.   


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on April 23, 2013, 03:56:11 AM
...My neutral and ground are separate and distinct.  There is no stray voltage on the ground or neutral either....

They had better not be.  They have to be connected together in the breaker panel.  If they aren't, then that is most likely your problem--and if that is the case, I'd suggest getting an electrician to fix it, because your home electrical system isn't up to code.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 23, 2013, 04:55:04 AM

The pc and light switch on in the same circuit that I am complaining about.  What's weird is when I went to test it tonight of course I could not reproduce the issue! Even with my rotor controller!!

I'm wondering if there is a device that is plugged in that is amplifying the signal on the circuit or whole house which is now NOT plugged in and why it's not surfacing.

I'm still searching.

Problems like you describe are often intermittent.  You didn't respond to my questions about other loads/appliances in other parts of your home.  Especially, 240 volt loads such as an air conditioner compressor, oven range, or electric range oven element.  If the arcing is only on the circuit that supplies your rotor and PC, then it's most likely what I suspected as to it being a screw terminal or wire nut somewhere between the outlet that supplies your PC and your main panel.




Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on April 23, 2013, 05:06:59 AM
...My neutral and ground are separate and distinct.  There is no stray voltage on the ground or neutral either....

They had better not be.  They have to be connected together in the breaker panel.  If they aren't, then that is most likely your problem--and if that is the case, I'd suggest getting an electrician to fix it, because your home electrical system isn't up to code.

Separate and distinct probably was his definition of them being two separate conductors from the main panel to the outlet(s) in question.  "No stray voltage" would be normal if nothing was turned on.  But, one should expect a small voltage rise on the neutral at a significant distance from the main panel under load due to the neutral conductor resistance.  He would have a code issue if the grounding conductor and neutral were interconnected anywhere else besides the main panel.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 23, 2013, 06:19:13 AM
Yes... thank you for clarifying my statement.

I dont believe its a fundamental issue with my electrical system as the issue does not resonate on any other electrical device (including a house hold AM radio) - I do believe though my poor RF ground (water pipe), location of my rig (second floor),  location of my antenna (over the side of my house on a mast which is literally 33 feet above the electrical panel) are major contributors.  This weekend I will try a few things to isolate the problem.  I am also planning on putting a better ground outside my antenna - that will come soon...

Thanks for all the feedback and what to look for.. I will report back on my progress.

...My neutral and ground are separate and distinct.  There is no stray voltage on the ground or neutral either....

They had better not be.  They have to be connected together in the breaker panel.  If they aren't, then that is most likely your problem--and if that is the case, I'd suggest getting an electrician to fix it, because your home electrical system isn't up to code.

Separate and distinct probably was his definition of them being two separate conductors from the main panel to the outlet(s) in question.  "No stray voltage" would be normal if nothing was turned on.  But, one should expect a small voltage rise on the neutral at a significant distance from the main panel under load due to the neutral conductor resistance.  He would have a code issue if the grounding conductor and neutral were interconnected anywhere else besides the main panel.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: N8YQX on April 23, 2013, 04:43:58 PM
Is your AGC adjustable?  Fast AGC should minimize the problem.

I have similar problem with the whole house humidifier.  The water is regulated with a solenoid, and when it kicks in, it causes a broadband noise (impulse noise).  If the AGC is set to slow response, the release time is long, and it can be quite annoying.  With fast AGC, my release time is quite fast, and I only miss one syllable at most.

I know this is not the ideal solution, but if your radio has an adjustable AGC, it's a quick fix until you get the problem resolved properly.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KB3HG on April 24, 2013, 10:57:03 AM
FWIW,
Get a CHEAP transistor AM radio. the cheesier the better turn it on, have someone flip switches, the AM radio will go nuts from the noise the closer you are to the problem. Is a  simple way to locate the source.

Blind guess a loose connection. At the panel or common point ground. 



Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD2CJJ on April 26, 2013, 06:35:18 AM
I did some tests... the issue is MOSTLY localized to the circuit that the shack is on.  Other circuits dont produce the issue except for my boiler when the blower turns on... but its a very small blip.  I was wrong in this fact. Keep in mind though my shack is on the second floor story of my house, the feed-line goes up into the attic across then up again out then up to my mini beam hanging off the side of the house.  Its about 40 feet of feedline.. the antenna is about 15 feet above my shack to the side about 20 feet.

I played around with some settings the AGC does help but then it affects the listenability when I have my RF gain up.  The Noise Blanketer completely eliminates it if I set it to 30%....  Im fine leaving the NB on at 30% as it doesnt affect my listenability....  In the long term I will hunt down why with an AM radio (funny I dont have one).

Lastly I did notice that the issue is a "typical" issue based on my internet search.  Any device that has a high current draw will create a small spark when plugged in (you can test it for your self. With that said, the light switches in my house seem to make a small spark when I turn them on/off... From my research this is somewhat normal for "cheap" light switches.   Every light switch that creates this "small spark" creates this annoying spike.  In parallel I will replace all these cheap light switches - of course this will NOT fix my issue with the switches on my rotor.

I will report back..

PS do a google on "why is there a spark form the light switch when I turn on or off the lights" to read on what I found..

FWIW,
Get a CHEAP transistor AM radio. the cheesier the better turn it on, have someone flip switches, the AM radio will go nuts from the noise the closer you are to the problem. Is a  simple way to locate the source.

Blind guess a loose connection. At the panel or common point ground. 




Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KB9YNB on April 30, 2013, 12:46:27 AM
...My neutral and ground are separate and distinct.  There is no stray voltage on the ground or neutral either....

They had better not be.  They have to be connected together in the breaker panel.  If they aren't, then that is most likely your problem--and if that is the case, I'd suggest getting an electrician to fix it, because your home electrical system isn't up to code.

Slight correction:  The ground an neutral should be connected at the first disconnect after the meter.  If your breaker box is located far away from your meter, then you probably have a disconnect at/near the meter, which is where your ground and neutral will be bonded.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on April 30, 2013, 04:16:26 AM
Slight correction:  The ground an neutral should be connected at the first disconnect after the meter.  If your breaker box is located far away from your meter, then you probably have a disconnect at/near the meter, which is where your ground and neutral will be bonded.

Not quite.  The neutral and the ground should be bonded together at the breaker box, and usually are by the simple method of directly mounting both the neutral busbar and the ground busbar directly to the metal breaker enclosure.  The meter socket does not have a 'ground' connection point, it has a 'neutral' connection point since the neutral is one three cables connecting the breaker box to the meter in a typical three wire 240 volt household system with the other two cables being the two opposite 'hot' phases of the system.  That neutral connection is the connection that is 'grounded', for all intents and purposes.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KD0REQ on April 30, 2013, 08:52:52 AM
what happens if you string an extention cord and put the radio on a different circuit for temporary testing purposes?  yes, if you have a silly ground situation, this may make metal surfaces "hot" with RF in the shack, it may not.

W6EM knows what he's talking about, and now that it's apparently isolated to the shack circuit, time to nail that one down for sure.  it could be a backstab connection downstream, or even a breaker that has "chattered" contacts, but it's sounding like a crummy contact someplace in that circuit.  if true, first step for me would be to replace every outlet and switch on that circuit with screw-down back-wired devices, and check the wire nuts to make sure the wires were twisted before being inserted into the wire nuts.  those two steps could get the high resistance piece out of your way forever.

and indicate a continuing improvement project in the house.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: N1UK on April 30, 2013, 09:57:03 AM
I had a similar loose connection issue to what W6EM talks about. One day I switched on the Astron 35 amp PSU in my shack and everything went off. I checked the breaker and it was fine. Then I noticed that the first socket in the shack 115V string was working. I turned off the power at the breaker box and removed the working receptacle from the wall. I could see that the neutral white wire was not making a good contact. The screw was loose and the white insulation had darkened over time with the resistive heating. This is the sort of thing that W6EM states causes house fires. I removed the connection, cleaned up the copper until it was bright and clean and then remade the neutral screw connection to the receptacle tightly this time. I was lucky to find this problem.

If it was me..I would check all the connections in the shack circuit for loose connections, including the breaker connections. It might help to replace the breaker on this circuit. They are cheap. I replaced all the 40 year old breakers in my house a few years ago and I swear that the lights in the house seemed brighter at night.


73 Mark N1UK


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K8AXW on April 30, 2013, 08:37:00 PM
UK:  This is a situation that shouldn't be considered "resolved" as soon as the problem is found and "corrected."

Many times when a conductor has overheated it changes the molecular structure of the copper wire and quite possibly the receptacle contact that it was attached to.

While your "fix" was probably fine, I would have been more comfortable if the receptacle was replaced and the wire end was cut off and a new section of the wire was used for connecting to the new receptacle.

At the very least, I would have checked it periodically for several months.  Perhaps this might be considered paranoia but I HAVE seen what happens to hot wire.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on May 01, 2013, 09:12:47 AM
UK:  This is a situation that shouldn't be considered "resolved" as soon as the problem is found and "corrected."

Many times when a conductor has overheated it changes the molecular structure of the copper wire and quite possibly the receptacle contact that it was attached to.

While your "fix" was probably fine, I would have been more comfortable if the receptacle was replaced and the wire end was cut off and a new section of the wire was used for connecting to the new receptacle.

At the very least, I would have checked it periodically for several months.  Perhaps this might be considered paranoia but I HAVE seen what happens to hot wire.

Copper wire that is used in listed branch circuit cables is soft-drawn or annealled soft copper.  The caveat is, in making connections via a connector, is that the conductor itself does not neck-down and lessen in cross-sectional area.  The resistivity of the base metal won't change much, if at all with respect to hardness.  Remember that the resistance is directly proportional to length and inversely proportional to area.  Ideally, in a compression connection, the connector metal "moves," and the conductor does not.  A screw, however, shouldn't be soft.  It needs to dig into the copper conductor and hold it firm.

You are right with your recommendation.  To be sure, change out the outlet where the screw and conductor were overheated.  The other thing that usually happens is that the PVC insulation close to the hot spot will exude anhydrous chlorine gas.  This will corrode bare copper and in extreme cases, turn it green and develop a blue-green "ooze" all over it near the hot spot.  And, the nearby insulation becomes quite crispy and ineffective in the process.

The nomenclature of grounded conductors is a tad confusing.  Back several editions of the NEC, they renamed the neutral or white conductor the "grounded" conductor.  Why?  Because it's connected at the service entrance to the "grounding electrode conductor" from the ground rod or other means of grounding and tied to the green or bare "equipment grounding conductor."  It's more confusing now because the white "grounded" conductor can and does very often have voltage impressed upon it beyond the common connection point.

73,

Lee


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on May 01, 2013, 09:45:45 AM
...replace every outlet and switch on that circuit with screw-down back-wired devices, and check the wire nuts to make sure the wires were twisted before being inserted into the wire nuts.  those two steps could get the high resistance piece out of your way forever....

All too often, outlets installed are connected simply by pushing wires into spring clip type connectors in the back of the outlet itself.  Although that type connection may be trouble free, just let the outlet get heated by a bad plug or connection, and that spring clip may lose its resiliency.

I do my own wiring (worked for an electrician in my earlier years) and when I replace outlets and switches I always strip the wire and use the screw connectors on the outlet/switch.  It's simply a better connection method, and one that can eliminate the type trouble you're experiencing--if those spring connection are the cause.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KB5UBI on May 01, 2013, 11:54:24 AM
Nothing to worry about; it's just the NSA bugs installed in your house.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KB9YNB on May 01, 2013, 06:17:20 PM
Slight correction:  The ground an neutral should be connected at the first disconnect after the meter.  If your breaker box is located far away from your meter, then you probably have a disconnect at/near the meter, which is where your ground and neutral will be bonded.

Not quite.  The neutral and the ground should be bonded together at the breaker box, and usually are by the simple method of directly mounting both the neutral busbar and the ground busbar directly to the metal breaker enclosure.  The meter socket does not have a 'ground' connection point, it has a 'neutral' connection point since the neutral is one three cables connecting the breaker box to the meter in a typical three wire 240 volt household system with the other two cables being the two opposite 'hot' phases of the system.  That neutral connection is the connection that is 'grounded', for all intents and purposes.

No, really.   If your "main" breaker box is not the first "disconnect" after the meter, then the ground/neutral will not be bonded there.  (It may depend on the age of your house and which NEC was in effect when it was built)

For instance, my house has a "disconnect" immediately next to the meter base, because my house breaker box is more centrally-located in the house.   The ground/neutral are required to be bonded at the very first disconnect after the meter, which is not *always* in the breaker box.



Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K8AXW on May 01, 2013, 08:58:06 PM
EM:  It has been my observation that on occasion an overheated conductor takes on a crystallized appearance and becomes brittle.  Natural vibration caused by anything from machinery running or the house expanding and contracting to the wire vibrating in the walls can cause this fragile looking wire end to simply break.

It isn't common but can happen.  I always sleep much better when I don't take chances with my wiring.  Again, this might be paranoia but I can live with that too.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on May 02, 2013, 04:02:29 AM
...For instance, my house has a "disconnect" immediately next to the meter base, because my house breaker box is more centrally-located in the house.   The ground/neutral are required to be bonded at the very first disconnect after the meter, which is not *always* in the breaker box.

As does mine.  I believe that you've hit on it with your statement--
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It may depend on the age of your house and which NEC was in effect when it was built.

One other thing,  I have never come across a feeder cable (meter to breaker box) that has both a neutral AND a ground cable in it.  They are both the same.  Also, I've never seen a breaker box that has both the ground bus and the neutral bus NOT connected directly to the metal of the box.  In any event, it's a moot point, since this is a ham radio site, not an electricians wiring site! 


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on May 02, 2013, 04:41:48 PM
One other thing,  I have never come across a feeder cable (meter to breaker box) that has both a neutral AND a ground cable in it. 

That is because it is technically the service entrance from the utility into the main breaker or fused switch main disconnecting means.  The grounding electrode conductor and the utility neutral are tied together and at that point, the neutral becomes the "grounded" conductor.


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They are both the same.

Only at the enclosure housing the main disconnecting means.

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  Also, I've never seen a breaker box that has both the ground bus and the neutral bus NOT connected directly to the metal of the box. 

Apparently, you have never seen a sub panel downstream from a main panel.  When you purchase a breaker panel, the neutral bus is insulated for a reason.  Just that.  In case it is destined for use as a sub panel.  Usually, the manufacturers include a "grounding screw" which can be used to ground the bus to the metal can if it is going to be used as a main panel.


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KB9YNB on May 02, 2013, 06:27:28 PM
...For instance, my house has a "disconnect" immediately next to the meter base, because my house breaker box is more centrally-located in the house.   The ground/neutral are required to be bonded at the very first disconnect after the meter, which is not *always* in the breaker box.

As does mine.  I believe that you've hit on it with your statement--
Quote
It may depend on the age of your house and which NEC was in effect when it was built.

One other thing,  I have never come across a feeder cable (meter to breaker box) that has both a neutral AND a ground cable in it.  They are both the same.  Also, I've never seen a breaker box that has both the ground bus and the neutral bus NOT connected directly to the metal of the box.  In any event, it's a moot point, since this is a ham radio site, not an electricians wiring site! 

It's not a moot point, because you have told people that their breaker box MUST have the neutral bonded to the ground.    This should ONLY be true if your breaker box is the MAIN disconnect.  Not ALL breaker boxes (even if it's the only one in your house) also serve as the MAIN disconnect.

You should NEVER see a service entrance cable from the Meter to the MAIN with a ground wire.     


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: W6EM on May 03, 2013, 06:22:13 PM
EM:  It has been my observation that on occasion an overheated conductor takes on a crystallized appearance and becomes brittle.

Overheating will anneal and soften conductors; or if hot enough, (1083C) overloading will melt or "fuse" copper.  Heat never crystalizes.  You may have observed surface pitting from acid gas corrosion from cooked PVC insulation nearby.

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  Natural vibration caused by anything from machinery running or the house expanding and contracting to the wire vibrating in the walls can cause this fragile looking wire end to simply break.

I'll buy off on machinery work hardening solid conductors, but not structural thermal/moisture expansion or contraction.  More likely, if a receptacle or switch was not sufficiently tightened to the junction box, and it were to move back and forth enough, that might cause something to fail.  Best to use higher strand class stranded copper for things like motor leads.



Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: K1CJS on May 04, 2013, 08:42:45 AM
...Apparently, you have never seen a sub panel downstream from a main panel.  When you purchase a breaker panel, the neutral bus is insulated for a reason.  Just that.  In case it is destined for use as a sub panel.  Usually, the manufacturers include a "grounding screw" which can be used to ground the bus to the metal can if it is going to be used as a main panel.

I have, but we weren't talking about a sub panel, nor were we speaking of how the panels come from the manufacturer, were we?  You can always throw 'buts' or 'how abouts' into a discussion--way after the point of the discussion.  After all, the discussion was about the wire connections between the meter socket and the breaker panel is done, not sub panels, nor how new breaker panels from the manufacturer come!  All you're doing is muddying waters for those who really don't understand.  Do you know what 'nitpicking' means?


Title: RE: Question for Elmer - Audio blip when turning off any power source in my house
Post by: KA5IWO on May 04, 2013, 11:02:46 AM
If you are comfortable with working on your on AC power mains and know the obvious dangers, you can probably fix this yourself.
Pull the meter base out, even if you have to cut the power companies tamper seal. If they ask, tell them an electrician did it. Never had a problem in my area with this but you may want to check. Check the lugs on the DEAD side of it first to make sure they are tight. Do NOT TOUCH the incoming wires to the meter from the power grid AS IT IS STILL HOT. Then proceed to your breaker box, find the incoming power wires to it from the meter base, check all connections in it starting with incoming power lugs first. If need be, pull and reseat all the breakers. Make sure all your hot wires, neutrals and grounds are good and tight and verify your outside ground connection is good.
PLEASE call an experienced electrician to do this for you if you do not feel safe doing this.
Most of all be safe.
Kevin / KA5IWO