Third stereo receiver..lightning

[davidlee]

Lightning just took out my third stereo receiver in two years. It is in my shop which is about 150 feet from my main power supply. I have a 100 amp sub panel in the shop fed with a four wire system, two hots, one neutral and one ground. All are run back to the main panel. The shop sub panel does not have any ground rods connected to it, just grounded back to the main. I had the receiver plugged into a surge protector and the receiver was not on at the time of the strike. I also had a plug in time clock and a mini fridge on the same surge protector and they had no damage. I used the word strike but I did not mean a direct hit just a loud clap of thunder in the middle of the night. Nothing else in the shop has received any damage just the stereo. I am getting tired of buying new ones. any ideas other than unplugging it when I am not out there?

 

[BillK]

Dave,
What type of antenna do you have on it ? Is it actually getting into the power side of the receiver or maybe in through the antenna and killing the input circuit ?

 

[davidlee]

No antenna, just a typical Onkyo receiver.

 

[iron block]

1. What kind of receiver (make, model)?
2. Is it totally dead (not even lighting the panel lights), or does it light up but just not produce sound?
3. Does it make any strange noises or smells when you try to turn it on?

 

[davidlee]

No lights no sound no smell. I took #2 apart and found a blown (burned out ) strip on one of the circuit boards .I was able to solder in a patch wire but that did no good. I did check the small glass fuses (3) and they were all good. I am not good at electronics.
Onkyo 8020 I believe. It is only two months old. OUCH

 

[jackfork]

Typical receivers have antennas for the tuner.

 

[davidlee]

I thought he was speaking about an outside antenna. Yes it has a small wire antenna which is inside the room. No signs of damage to it or the surrounding area.

 

[BillK]

I had the receiver plugged into a surge protector :

Dave,
Just thought of something because I bought a new surge protector the other day for the shop computer. The one I bought had a guaranty that covers up to a certain amount of equipment replacement costs. Any chance the one you have does the same ??

 

[davidlee]

Yes it does but I am trying to get to the source of the problem if I can. Nothing else seems to get damaged and I can't figure out why.

 

[DC73]

Florida is the lightning capital of the U.S. with more frequent and stronger lightning strikes than most other places. But that doesn't mean you have to settle for replacing electronics this often.

Double check your grounds to start with. Check your main ground for a good connection. I had similar problems at a previous house and finally discovered the ***** electrician who wired the place connected a copper ground wire to a copper ground rod with an aluminum ground clamp. The ground clamp had disintegrated leaving me with no ground.

Check all grounds from the main ground back to and including the outlet serving the stereo.

You might also call the local power company service department and explain the problem to them. Do this especially if you don't find anything on your side of the meter. They might have grounding issues with your service. They should also be able to advise you on a course of action. Many power companies have power quality specialists who handle these sorts of problems.

DC

 

[davidlee]

Thanks, I'll check the grounds tomorrow and report back.

 

[BillK]

Nothing else seems to get damaged and I can't figure out why.

David,

The clock and the fridge probably do not have any components that are as "fragile" as the receiver. The other thing is that most modern receivers are not really "off" when you turn the power off on the front panel, they are really in a standby mode so there is still power to a lot of the circuits.

Like DC said, you probably should be checking all of your grounds real good. Also, might not be a bad idea to replace the surge protector, it is possible that it has gone bad ?

 

[davidlee]

The receiver was plugged into the time clock. I checked the clock and it opens and closes the hot side but the neutral is not broken when off. I don't know how to check the surge protector but the green light is still on and it still has power going through it as normal.

 

[BillK]

The receiver was plugged into the time clock.

That could even be part of the problem. Why not plug the receiver directly into the surge protector ?

 

[davidlee]

I was not clear sorry, Receiver plugged into time clock, time clock into the surge protector. That way the stereo comes on automatically in the AM and goes off in the PM.

 

[coralnut]

Nothing else in the shop has received any damage just the stereo. I am getting tired of buying new ones. any ideas other than unplugging it when I am not out there?

You're probably assuming that it took the hit through the power cord. that's the immediate assumption that most people make, but it's not the only route of entry for lightning energy into your receiver.

You need to consider all of the wires that are hooked up to your receiver. Including the antenna, any RCA wires that might be going to other components, and most important of all -- your speaker wires. Your speaker wires are long, heavy, and right up against the wall. They present a nice antenna for induced EMF. It's not at all uncommon for lighting strikes to find their way into electronics via inductive currents in the speaker wires.

I've repaired a lot of lightning damaged electronics. I bought a Carver amplifier on eBay that got struck by lightning, and the route of entry was via 3 different circuits -- power cord, speakers and interconnects. The strike took out the output transistors, output relay, protection circuit, front panel meters, input/drivers, and power supply. That one was a ***** to repair. I should have just scrapped it, but it was one of those cases where every time I fixed one thing I found out that something else was damaged.

Moral of the story: buying a surge protector and unplugging the receiver from the wall isn't good enough. You also need to disconnect the speaker wires, the antenna and any other wires going to other devices. But nobody ever does this.

 

[wyliesdiesels]

The big question here is WHY u dont have grounding electrodes, especially considering u live in Florida.

And I would add surge suppressors to your electrical panels if this keeps happening...

 

[ModClean]

most important of all -- your speaker wires. Your speaker wires are long, heavy, and right up against the wall.

Legit issue here. There are surge protectors available to go between speaker wire-runs and the receiver to prevent this. Believe they were initially conceived for outdoor speakers, though obviously that is not their only use. But, before you bother with that...

The big question here is WHY u dont have grounding electrodes, especially considering u live in Florida.

↑↑ This. Florida, and 150ft from main service grounding, to boot.

 

[DonPowers]

I installed a lightening arrester in my electrical panel. It’s a cylindrical thing that sits in the bottom of the panel and is tied to the main breaker. It can also be connected to any 220 breaker.

Also have surge suppression on most all electronic items.

 

[CNGsaves]

Obviously time for 2 ground rods at the subpanel at garage.

Also could add lightning rods to the roof so you give it even better path to ground !!

 

[sberry]

Is this a 2 wire device? There is a current install on this old house in Fla. The mist important part of the surge is the rest of the grounding system, I would be looking to make sure it was all connected and adding a couple rods at the garage.
I am with a couple of the guys here that wouldn't simply jump to the conclusion it was a strike to the power or a "surge" and run out to put yet another device on and feel cozy about it. I think surge is an over used word that usually comes up in speculative trouble shooting.

 

[sberry]

The receiver could be sitting on a well grounded appliance? I agree to look at other ways there was a problem. There used to be an issue with phone companies, I had my own with strikes until I went to Article 880 and pondered that a while, I quiz up the phone tech and he doesn't know squat.
Puters used to have internal modems hooked to phone lines and grounded electrical systems. He doesn't "understand" and only reluctantly pounds a rod which in this case was missing and not bonded to the electric service main which is the best. (14 or better wire for phones and usually bugged to the wire to ground rods.)
I have had coincidence too, is this the same piece of equipment hooked to the same source thru the same timer etc? Get a different brand.
I think most of Fla has a high water table, it can be humid and as I recall aluminum corrodes there. I would be tempted to follow the ground wire from the service main to rods, any metal piping, any cable, phone service or dish with wire to the main and add 2 rods to the garage service as well as ground anything metal in sight to it.

 

[davidlee]

First, thanks for all the replies. I do have two outdoor speaker tied to the system but the indoor speakers(4) are ceiling mounted between two floors and not on any exterior walls. So far I have not had any speaker damage.

As to the no ground rods on the shop sub panel, I thought the only rods used were located at the main panel and any other rods would just create a problem. It will not be too difficult to add them at the sub if it would help.

The receiver is sitting on its own wood shelf and not touching any metal at all.

 

[westom]

Thanks, I'll check the grounds tomorrow and report back.

What were you going to inspect? The connection from every incoming wire (including phone and cable) must connect low impedance (ie less than 10 feet) to single point earth ground. All four words have major significance.

Maybe three AC wires enter. All three must make that connection. One connects directly - for best surge protection. Others must make the same connection via a protector. That protector only does what a direct connection does better.

Obviously a power strip protector was not recommended. Always grasp numbers - ie less than 10 feet.

As coralnut noted, every wire in every cable must make that low impedance (ie no sharp bends) connection. This post only introduced what you must know to inspect or to have protection.

Protection is always about where hundreds of thousands of joules harmlessly dissipate. Once you let a surge inside, then nothing will avert a destructive hunt for earth via appliances. You have seen (at least three times) what happens when you all but invited a surge inside.

More numbers. Lightning is typically 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. Effective protection means even the protector is unharmed after a direct strike.

 

[DC73]

What were you going to inspect?

He's going to inspect the ground path from main power back to the stereo outlet for any obvious problems. Sometimes it's as simple as a finding a loose connection. Making sure you have a solid ground path is step 1 in tracking down problems like this.

More numbers. Lightning is typically 20,000 amps.

The average is higher in Florida. Lightning strikes in Florida can easily approach 100,000 amps and some can be on the order of 200,000 amps. Lightning strikes can be either positively or negatively charged. Positive lightning strikes can be 5 to 10 times more powerful than negative strikes. Florida has an abundance of both kinds.

DC

 

[westom]

He's going to inspect the ground path from main power back to the stereo outlet for any obvious problems. Sometimes it's as simple as a finding a loose connection. Making sure you have a solid ground path is step 1 in tracking down problems like this.

That ground can be perfectly fine (meet code). And still be woefully insufficient for protecting household appliances. As was explained in the previous post.

Almost nobody sees a 100,000 amps surge. However a 100,000 amps surge to AC mains means 40,000 amps to earth via the 'primary' surge protection layer (installed by the AC utility). 20,000 amps to other homes. And 40,000 amps into this home. These numbers from a 1870s IEEE paper. So a 50,000 amps 'whole house' protector is sufficient. If not, thena 100,000 amps protector is recommended.

But again, no protector does protection. Protection is provided by earthing - that must both meet and exceed code requirements. So that every wire in every incoming cable (ie invisible dog fence, sprinklers, antenna) make a low impedance connection to the same earth ground ... which is only a 'secondary' protection layer.

 

[gdh33]

About the suggestions of grounding rods at the garage. Since he has 4 wires feeding his sub panel and the main feed to his house should be grounded at the first device, wouldn't installing other grounding devices cause a ground loop? I thought grounding at a sub panel was only done when you are so far away from the service panel (first ground) that you run 3 wires to the sub panel and ground it there and do not connect it to any other grounds?

 

[iron block]

No lights no sound no smell... I did check the small glass fuses (3) and they were all good...

This narrows things down a bit.

1. If the lightning energy entered along the speaker wires and destroyed the output circuit -- which can certainly happen -- we would expect that the next time the receiver was turned on, the shorted outputs would cause a main fuse to blow. Or, if you were really lucky and the outputs failed open rather than short, the receiver would light up but you would not get any sound out. Since neither of those things applies, there is probably something else going on.
2. Receivers that have a remote control to turn them on, like this one, need to have a source of "standby" power than is always energized. This power then feeds the microprocessor and the infra red receiver module, so they are always ready to act on a remote control sending a power up command. Two things could have happened to damage this subsytem:
   • The standby power supply might have been taken out by the surge. It probably does not have an easily-visible fuse, unlike the main power supply. In fact, its protection may be something like a fusible resistor -- and those open up without any external sign. This is a case for a technician to investigate. A service manual would be helpful, but maybe not essential.
   • The microprocessor might have been damaged by the surge, perhaps by overvoltage from the power supply during the surge. If the micro is kaput, you might as well toss the receiver as it would not be practical to repair it.

It's not looking good. Sorry.

 

[davidlee]

Iron block, I understand what you are saying about standby power but wouldn't that not be the case since the unit is turned off by the plug in timer not the stereo switch?
The timer does break the hot side but not the neutral. I checked it with my meter. I do believe the receiver is toast now. I am just trying to prevent the next one from the same fate.

Yes we are the lightning strike capital of the U.S. in NW Florida.

I would also like some feedback from the post by gdh33. That is why I did not ground the sub panel. Am I wrong?

 

[ModClean]

I would also like some feedback from the post by gdh33. That is why I did not ground the sub panel. Am I wrong?

I don't think anyone was advocating creating a loop. You have one ground running from the main service. It is not (I hope) bonded to the neutral at the garage box. So, when you add grounding rods at the garage you have simply forked off the ground circuit to... the ground. It does not "loop" with anything. Electrically, it is not really that dissimilar in configuration from having four grounding rods at the main service--it's just that two of those rods have 150ft between them and the main panel and don't have 150ft between them and the sub-panel.

 

[gdh33]

Thank you ModClean, I had forgotten and was hoping for clarification as it is not common here.

 

[DC73]

I don't think anyone was advocating creating a loop. You have one ground running from the main service. It is not (I hope) bonded to the neutral at the garage box. So, when you add grounding rods at the garage you have simply forked off the ground circuit to... the ground. It does not "loop" with anything. Electrically, it is not really that dissimilar in configuration from having four grounding rods at the main service--it's just that two of those rods have 150ft between them and the main panel and don't have 150ft between them and the sub-panel.

Agreed. Ground loops can happen when two separate electric services (with separate grounds) are somehow commonly connected. For example, if you had a separate electric service to a shop including a separate ground, but had a common link between the house and shop such as a CAT5, phone or other cable, then, if lightning struck nearby, it could set up a potential difference between the two ground points and the common connection would then carry the current. To resolve problems due to a situation like this example, one solution is to bond the two grounds together.

DC

 

[davidlee]

DC73, Thanks for the info. I understand now. You explained it well.

What doesn't make any since to me is that for a number of years we had an el cheepo stereo receiver in the shop and never had any problems. We also have a good receiver in the house with no problems and yet when I got a good one for the shop, problems. Maybe lightning just likes Onkyo. LOL.

 

[westom]

Electrically, it is not really that dissimilar in configuration from having four grounding rods at the main service--it's just that two of those rods have 150ft between them and the main panel and don't have 150ft between them and the sub-panel.

That is about grounding for human safety. Grounding to protect appliances from surges involves additional factors including equipotential, conductivity, and impedance.

If a building is 150 feet away (and not properly earthed for surge protection), then it can even act like a lightning rod connected to appliances in a main building. When a connection between structures is that far apart, then each end must connect to a single point earth ground where it enters that structure. Connected directly and low impedance (ie less than 10 feet) with a hardwire or via a 'whole house' protector.

What happens when lightning strikes AC wires far down the street? That current may be hunting for earthborne charges miles beyond a secondary building. Best path is incoming to the main building, into a secondary building via that 150 foot buried electric cable, into a stereo, and then outgoing to earth via speaker wires. Does not matter if a stereo is on or off (that should be obvious).

Damage is often on an outgoing path (ie speakers). Many who conclude only from observation would then wildly speculate a surge was incoming on speakers.

Obviously protection means connecting any destructive surge to earth BEFORE it could enter any building. That means single point earth ground for each building. Earthing that both meets code and exceeds code requirements (ie low impedance). Every wire inside any incoming cable must connect low impedance to that single point earth ground BEFORE entering.

None of this is new. Protection was routinely implemented this way over 100 years ago. Protection is about how a current gets to earth - and where hundreds of thousands of joules harmlessly dissipate.

If buildings are 150 feet apart and both do not have their own single point earth ground, then appliances in both buildings are at serious risk from an anomaly that might occur once every seven years (obviously more frequently in FL).

 

[BruceMc]

What doesn't make any since to me is that for a number of years we had an el cheepo stereo receiver in the shop and never had any problems. We also have a good receiver in the house with no problems and yet when I got a good one for the shop, problems. Maybe lightning just likes Onkyo. LOL.

Maybe. I lost my Onkyo a couple of weeks ago to a strike. Or more specifically, lost the HDMI circuitry on the receiver and TV, while the PS3 that was also connected seems to have survived.

 

[wyliesdiesels]

Obviously time for 2 ground rods at the subpanel at garage.

Also could add lightning rods to the roof so you give it even better path to ground !!

Those are called 'Air terminals' and are used on all major towers...

First, thanks for all the replies. I do have two outdoor speaker tied to the system but the indoor speakers(4) are ceiling mounted between two floors and not on any exterior walls. So far I have not had any speaker damage.

As to the no ground rods on the shop sub panel, I thought the only rods used were located at the main panel and any other rods would just create a problem. It will not be too difficult to add them at the sub if it would help.

The receiver is sitting on its own wood shelf and not touching any metal at all.

no adding grounding electrodes will not cause ANY problems. Contrary to popular misconception, ground rods under normal conditions do NOT have electricity flowing on them.

Code requires grounding electrodes on all detached structures!

About the suggestions of grounding rods at the garage. Since he has 4 wires feeding his sub panel and the main feed to his house should be grounded at the first device, wouldn't installing other grounding devices cause a ground loop? I thought grounding at a sub panel was only done when you are so far away from the service panel (first ground) that you run 3 wires to the sub panel and ground it there and do not connect it to any other grounds?

Here we go again with the confusion on te fifference between EGCs and grounding electrodes!!

U are confused sir.

All new subpanels are required to be 4-wire. The ground wire in the feeder called an EGC, is a different animal than a grounding electeode. They serve differenet purposes.

Both are required on a detached structure.

Heres an article i highly suggest u read:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

What were you going to inspect? The connection from every incoming wire (including phone and cable) must connect low impedance (ie less than 10 feet) to single point earth ground. All four words have major significance.

Maybe three AC wires enter. All three must make that connection. One connects directly - for best surge protection. Others must make the same connection via a protector. That protector only does what a direct connection does better.

Obviously a power strip protector was not recommended. Always grasp numbers - ie less than 10 feet.

As coralnut noted, every wire in every cable must make that low impedance (ie no sharp bends) connection. This post only introduced what you must know to inspect or to have protection.

Protection is always about where hundreds of thousands of joules harmlessly dissipate. Once you let a surge inside, then nothing will avert a destructive hunt for earth via appliances. You have seen (at least three times) what happens when you all but invited a surge inside.

More numbers. Lightning is typically 20,000 amps. So a minimal 'whole house' protector is 50,000 amps. Effective protection means even the protector is unharmed after a direct strike.

Not sure where u get your info and why u only comment on threads that pertain to grounding, surges and lightning. Seems u wait around for just these types of threads.

When u spout off about how point of use protectors do nothing for protection, u obviously have never been in a communications control center for dispatch centers or radio towers, or server rooms.

Point of use protection is used all the time and effectively arrests surges....

One of things i do for a living is grounding for communications towers. Some of your info is wrong...

 

[wyliesdiesels]

I don't think anyone was advocating creating a loop. You have one ground running from the main service. It is not (I hope) bonded to the neutral at the garage box. So, when you add grounding rods at the garage you have simply forked off the ground circuit to... the ground. It does not "loop" with anything. Electrically, it is not really that dissimilar in configuration from having four grounding rods at the main service--it's just that two of those rods have 150ft between them and the main panel and don't have 150ft between them and the sub-panel.

Wrong. As i said above, EGCs and grounding electrodes are 2 different animals.

An EGC is for providing a low impedance fault path for fault current to flow on so breakers can clear a fault. Without this, a breaker wont open/trip on a ground fault.

Grounding electrodes on the other hand are for grounding loghtning as well as limiting surges caused by PoCo primary lines arcing on secondary lines and limiting the voltage to ground.

Fault current doesnt flow on grounding electrodes.

I really wish people would stop confusing the 2.

Please please read the article i listed in my previous comment.

Thank you ModClean, I had forgotten and was hoping for clarification as it is not common here.

I have never understand why the CEC doesnt call for grounding electrodes on detached structures for the reasons i listed above...

 

[wyliesdiesels]

Agreed. Ground loops can happen when two separate electric services (with separate grounds) are somehow commonly connected. For example, if you had a separate electric service to a shop including a separate ground, but had a common link between the house and shop such as a CAT5, phone or other cable, then, if lightning struck nearby, it could set up a potential difference between the two ground points and the common connection would then carry the current. To resolve problems due to a situation like this example, one solution is to bond the two grounds together.

DC

^^^^ This is how a ground loop can be created!

And it can also happen if the shops electrical was fed from the house but there is a communication link such as CAT5e.

For this reason, many people opt to use fiber optic cable between buildings to isolate them and negate any ground loops!

 

[gdh33]

Than you Wyliesdiesels for the responses. I obviously do not do this for a living.

 

[ModClean]

Wrong. As i said above, EGCs and grounding electrodes are 2 different animals.

Golly. People keep jumping on that post; I wasn't trying to give him a electronics dissertation, I was trying to give him an extremely non-technical explanation for why it is acceptable to add grounding electrodes.

In any case, while it was admittedly-- and again, intentionally--a very non-technical post, I don't understand how the statement you bolded is really wrong?