Popping from light switches and refrigerator


Help please! My amp just quit working and no one knows why! Two weeks ago the output light on my pre-amp burned out and there was no sound through the system even though the pre-amp tested fine when I sent it in for repair!

I just moved into a patio home (on a concrete slab) three weeks ago. WHEN the stereo actually works, the CD transport misreads and there's a pop out of the speakers when a light switch is flipped, the refrigerator door is opened or the refigerator cycles on.

I've had an electrical engineer look at it and said it was just line noise. I had an electrian come out last Friday and he couldn't find a reason. The three lines coming into the house were all tight and the breakers were all tight.

The light switches and refrigerator are on four different breakers. The electrician suggested running a dedicated line. The electrical engineer said that that wouldn't help since the switching noise seems to be bleeding through four different circuits now.

This happened (before the amp quit working) with both a tube pre-amp and solid state pre-amp. It happened with both a $2500.00 power conditioner and a UPS unit from my computer.

I lifted the ground on the transport, dac and pre-amp and the popping seemed to stop (for that day). The next day the power amp quit working altogether. I don't know what to do!

Chuck
krell_man
I had a similar--(I think)-- situation to that you describe. It turned out to be the common behind the meter where the power comes in from the street.
All your circuts share a COMMON Ground. A computer grade or medical grade circut could be pulled but the simple solution is to isolate a single circut from the 4 that you have and ground that one on a dedicated or non-shared ground. It should cost very little. This will stop the bleed. You will want to make sure that nothing else with motors or pumps are on that line. Most electricians are not aquanted with Audio Grade lines. You will find that you must be specific and might have to use more than one electrician before finding one that understands what you really want. The problem can also happen when the 3 prong outlets are placed in the socket and a ground is established with a metal strip that universally grounds each outlet to a common ground. Make sure that if they wire it is a NEW 3 WIRE Feed wire without a common ground.
>" I had an electrian come out last Friday and he couldn't find a reason. The three lines coming into the house were all tight and the breakers were all tight."<
>>>>>>

What kind of an electrician? Just a house wiremen? Or an Electrician that does trouble shooting and service work?
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Did the electrician check the voltage at the electrical outlet the audio equipment was plugged into? With a load connected?

Did the electrician check the voltage at the audio outlet and cycle the refrigerater on and off? Did the voltage decrease? increase?

Do you notice light bulbs burning out quicker than they should? Light bulbs of the same wattage brighter in some areas than in other areas in the house?

Is your incoming power lines, that feed your home, overhead, or underground?

Did the electrician check the grounding electrode connections? Clean and retighten? ( Incoming main water line if metallic is a primary grounding electrode). Did he do anything here?

How old is the house?
The popping noise can just be line noise as the engineer mentioned to you. When you break current flow suddenly this creates an inductive kick (short duration voltage spike) that needs to bleed off somewhere. I've got 10 gauge solid copper dedicated lines from my breaker box to my stereo, a copper water pipe based grounding system that should satisify even the most finatic, and I still hear the pop from one heavily loaded light switch circuit. An alternative might be to have an electrician install surge supressors at your breaker box, this should be pretty cheap.
For what it is worth, we had an intermittent short on a piece of equipment at work that drove us insane for a while. It was on a circuit fed from a large (80 breakers) panel, the short wasn't enough to open a breaker but it would give enough of a spike to blow the most voltage sensitive equipment fed from the panel every now and then.
Anyway, were its my stuff, I'd -
1. Take the measuresments mentioned in the note above & if possible hang a brush recorder or oscilloscope on the line & see if there is anything that comes and goes.
2. Wonder if a short inside the amp is what made your audio life sour, and be anxious to find out what is wrong with it from the shop.
3. Consider a dedicated line for the long term as mentioned above.
4. Once you get data from 1-3 the answer might be obvious.
On the bright side, problems like this are always very simple after you know the answer.
>"The popping noise can just be line noise as the engineer mentioned to you"<
>>>>>>>>>>>>>>
Imo he has a bigger problem than that....

A service entrance neutral conductor that is not bonded to earth ground can cause this problem among other problems.

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>"I just moved into a patio home (on a concrete slab) three weeks ago. WHEN the stereo actually works, the CD transport misreads and there's a pop out of the speakers when a light switch is flipped, the refrigerator door is opened or the refigerator cycles on."<
>>>>>>>>>>>>>
I assumed this equipment worked fine before he moved into this house.
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>"the refrigerator door is opened"<
>>>>>>>>>>>
25 watt incandescent light bulb?
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>"I lifted the ground on the transport, dac and pre-amp and the popping seemed to stop (for that day). The next day the power amp quit working altogether.'<
>>>>>>>>>>>>>>

>"The next day the power amp quit working altogether."<
>>>>>>>>>>>>>>
Imo not due to ac line noise.
==============
.
Thank you all for your thoughts. After talking to about a million people besides your feedback, I started replacing all of the contractor light switches and outlets in this four year old home. This way I can make sure that there are no loose connections there and I know that these new pieces are of a lot higher quality.

The electrical engineer came over and checked the breaker box thoroughly and the ground rod and connection, things the electrician never bothered to do for the $140.00 service run. I bought a PS Audio Power Plant 500, but can't test it out yet until I get the amp back. I'll try it and then the dedicated circuit to see if I can see what's going on.

Chuck
>"The electrical engineer came over and checked the breaker box thoroughly and the ground rod and connection,'<
>>>>>>>
By chance did you show him my questions?

>"I started replacing all of the contractor light switches and outlets in this four year old home."<
>>>>>>>

Though cheap switches they are still snap switchs. They (make) and (break) very quickly.
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Is a single ground rod the only grounding electrode you have? Do you have an incoming domestic water system pipe that is metallic, copper? If so there also should be a ground clamp ahead of the water meter. It is very important that the grounding electrode conductor/s are not broken, and that the connections are not corroded so as the service entrance neutral conductor would not be effectively bonded to earth ground, by means of the grounding electrodes. (Ground rod/s, incoming water pipe). These connections need to be checked and if necessary broken down, cleaned, and reassembled. Because we do not know exactly what problems may exist I do not recommend you do this yourself. If there is possibly a faulty connection on the neutral conductor coming in from the utility transformer to your main electrical panel you could get shocked.

Do you have a volt meter? How about an electric clothes dryer receptacle? If so here is what I want you to do. If it is the older style recept type, a three conductor type, it should resemble a "Crows foot." The two slots that are at an angle are the hot conductors. Insert the volt meter test leads one each in each of these slots. What is the voltage> should be anywhere from 220V up to 250V.
As for the other slot in the recept I want you to measure the voltage from this slot to each of the other two hot slots in the recept. Each of these two voltage measurements should read any where from 110V to 125V. What ever the voltage reading they should be fairly close to one another. Example if one side reads 120V then the other side should read close to 120V..

I have tried to explain things in simple layman terms.
JEA48 - "Imo he has a bigger problem than that...." . You may be right, or the popping might be coincidental to the other issues, or both. In any case, I don't see any reccomendations above that seem unreasonable and I keep wondering about the first thought from Avguygeorge.

Chuck - Great luck! And if you don't care please let us know how this one plays out, inquiring minds gotsta know.
It seems to me that your problem is from one of two sources: the refrigerator or the power company. The refigerator motor contacts, brushes or pull-in relay could be arcing, leading to induction or impules noise in the entire house wiring. These voltage spikes can easily fry a CD player's electronics and blow amplifier fuses. Pull the plug on the refigerator and see if the problem goes away with respect to the light switch pops.

Second, the power company has voltage transients carried through to your house from sources such as nearby building motors or on-site generators, transmission wire faults, or your neighbors could be polluting upstream with their motors, computers, etc. This is a bitch to track down. The only thing you can do is complain to neighbors but the utility has a responsibility to attempt a solution if the problem is on their end.

Without knowing anything else, voltage spikes are the most likely culprits for the equipment damage. EM/RFI pollution is the most probable cause of the popping. If it were my house, I would be looking to install an isolation transformer for the entire audio circuit and a TVSS in the main panel.
Jeff, I did not mean that noise, voltage transients, were not causing the popping sound from the speakers. I was only saying I think his problem may be more serious. Equipment failing.
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>" I don't see any recommendations above that seem unreasonable and I keep wondering about the first thought from Avguygeorge."<

>"I keep wondering about the first thought from Avguygeorge."<
>>>>>>>>

I agree, that is why I asked the questions in my first post and wanted him to do the test I described in my second post.

The utility transformer that feeds "Krell Man"'s home is a single phase 240V center tapped secondary winding. With this transformer secondary configuration only the unbalanced load will return on the neutral to the source. Example, if a total 120V connected load of 30 amps is connected between L1 and the neutral, and a total 120V connected load of 30 amps is connected between L2 and the neutral, 0 amps will return on the service entrance neutral back to the source, the utility xfmr. If in the above example the load between L2 and the neutral was, say, 20 amps then 10 amps of load would return on the service entrance neutral to the source.

If we were to use ohms law E = I x R we can find the total resistance of each 120V total connected load.

L1 120V total connected load, E= 120V I= 30 amps R = 4 ohms

L2 120V total connected load, E= 120V I= 20 amps R = 6 ohms

Now lets see what happens if the service entrance neutral has a faulty connection somewhere between the utility xfmr and the neutral bar in the main electrical panel. For the example the service entrance neutral conductor has been disconnected at the utility xfmr. Also at this point the earth ground has also been disconnected. Will come back to this later.

What we have is the L1 connected loads travel back to the electrical panel neutral bar, and the L2 connected loads travel back to the electrical panel neutral bar.
But with the loss of the service entrance neutral the two loads are now in series with one another.

The total resistance for the total 120V connected load on L1 is 4 ohms.

The total resistance for the total 120V connected load on L2 is 6 ohms.

Because the two loads are in series with one another we have a total combined resistance of 10 ohms.

E= I x R
E= 240V R=10 ohm
240/10 = 24 amps
(current is the same in all parts of a series circuit).

Now that we have the total current flowing in the series circuit we can find the voltage drop across each of the two connected loads.

E= I x R

L1 total connected load
R= 4 ohms I= 24 amps 4 x 24 = 96V

L2 total connected load
R=6 ohms I= 24 amps 6 x 24 = 144V

96V + 144V = 240V the source voltage.

I tried to keep this example as simple as posible. This would be purely resistive loads....

Now back to that earth ground disconnected for the example.
If reconnected it will change the voltage drop values.
Though NEC does not allow the earth to be intentionally used as a circuit current path, with the service entrance neutral conductor not connected current will flow through the earth back to the source. How? Utility companies bond every xfmr case and the centertap, the neutral, to earth ground. The current will also travel through your neighbors earth grounds to their electrical panels and travel out on their service entrance neutral conductor. The resistance of the soil will determine the amount of current that will flow.

>"I keep wondering about the first thought from Avguygeorge."<
>>>>
Could very well be....
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Overhead fed service

Connection in the meter socket.
Connection at the weather head.
Connection at the utility xfmr.
Connection at the electrical service panel.
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Underground fed service

Connection at the meter socket.
Connection at the utility xfmr.
connection at the electrical service panel.
*The service neutral conductor damaged under the earth. If aluminum is exposed directly to the earth in time it will deteriorate and corrode in-two. All it takes is for the outer insulated jacket to be damaged and the aluminum conductor exposed.




Jea48 - I really like the write up above, and think you may well be correct.
I'm still curious about the condition of the amp though. Chuck moved into the house 3 weeks ago, which makes me think that his audio equipment was moved and unaviodably bounced about at least a minor amount in the process at about the same time. Since the move there have been issues with all several components connected to a common circuit. So while I don't disagree with anything I've seen on this thread, it also seems like there is a chance that an intermittent high current draw from one of the audio components could cause similar issues. L dI/dT can be a bugger.

Jeff, here is some great reading material. It explains in more detail just how a single phase center tapped secondary transformer works. Take note that the two single phase secondary winding leads, L1 and L2, are not 180 degrees out of phase with one another with reference to the centertap of the winding. One of the big selling points of balanced ac power systems.....Single phase in single phase out.
http://www.ibiblio.org/obp/electricCircuits/AC/AC_10.html

Jim
I had the same problem in my apartment.
Thought about isolation transformers, power plants,
all the usually audiophile approved ideas.
Then I tried a ac line filter from a company
Sandy Gilman of Audio Den back in Stony Brook recommended.
elect-spec
http://www.elect-spec.com/acprot2.htm#Laboratory
Solved my poping noises.
GTF