lightning storm

You should have immediately unplugged your audio system from the wall outlet.

It's possible slight damage may have occurred to some circuit board traces. It's called electronic rust. 

I would suggest you unplugged your audio system from the wall outlet during lightning storms. 

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EMI damage? Recently my F150 sat next to a pine tree that took a hit. $5k damages to the electrical. Luckily no damage to my HT/music system however my modem & charger to my laptop did not fare so well.

I don’t think the damage was caused by EMI. More likely from an electromagnetic pulse (EMP).

 

Edit:

I ran across this device on the Net. Does it really work?

EMP & Lightning Protection for Vehicles (DC-12V-W)

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My system was hit by lightening, it traveled through the coax cable line into my video processor via HDMI and then hit my projector. I had everything on quality surge protectors but it didn’t matter. The electrician I took the equipment to for insurance purposes said that lightening likes to have a path in and out so having things plugged into different wall outlets is an issue.

The electrician I took the equipment to for insurance purposes said that lightening likes to have a path in and out

@hifidream ,

I’m pretty sure he meant more than one earth connection to the electrical grounding system of the house. (From mother earth to the inside of the house and back out of the house to mother earth.)

All mother earth connections should be connected to the main electrical service equipment, service entrance neutral conductor that is bonded to the metal enclosure of the electrical service equipment. That especially includes the shield of the CATV providers coax cable. 

On the outside of your house just before where the coax cable enter your house there should be a grounding block. (sometimes the block is mounted in a plastic weather proof/resistant enclosure).

Here is where it can get tricky. How close is the grounding block from the outdoors electric meter socket enclosure? More than 20 feet?

If  20ft or less a minimum #14awg copper ground wire, (I would use #12awg solid copper minimum), install from the ground block lug to the grounding electrode conductor that come outdoors from the main electrical service equipment and connects to a ground rod(s) in the earth. (Some times the electrical service equipment is mounted outdoors beside the electric meter socket enclosure).

Use an electrical split bolt to connect the #12awg solid copper wire to the #6 bare solid copper wire,  (#6awg solid bare copper is the minimum size per code). (I prefer #4awg bare solid copper wire).

 Clean the bare #6 copper ground wire with a piece of emery cloth or fine sand paper.

Example of a split bolt. 

If distance from the grounding block to the grounding electrode conductor is greater than 20FT post back for instructions.

Grounding and Bonding of Communications Systems   

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What the tech was referring to is that lightning potential seeks a path to ground, and will find the lowest insulated point to go through.  

Lightning is non discriminating. It will take any path that is provided to earth. The lower the soil to grounding electrode, (ground rod), resistance the better. Simple OHMS LAW.

Why give it two paths. In and out in the blink of an eye.

Let’s wait for @hifidream to respond to my post above. At this point we don’t know how the CATV grounding block is grounded. I can say if the CATV coax cable is on the opposite side of the house, than the electrical service is on, a ground stake was stuck in the earth and the grounding block was only connected to earth at the ground stake.  Lightning loves those type of grounding installations.  Lightning also loves audio isolated ground rods too.

Bonding communications systems

 

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@hifidream said:

I was living in a loft apartment at the time in the end unit of five in a row. I don’t know if the building was grounded properly.

There is an unknown. A lot of variables. Age of the CATV coaxial cabling installation the biggest one.  

I did not have the coax going though a surge protector which probably was the issue as you describe.

Not a surge protector. A grounding block. Two different animals entirely.  

Example:

CATV coax cable shield Grounding Block

As you can see its pretty basic. But when installed properly it gets the job done diverting a near by lightning surge to earth and most importantly to earth using the  System Ground, Grounding Electrode System, of the electrical service of the building, dwelling unit. 

The lower the grounding electrode to soil resistance the better for diverting the high voltage surge to Mother Earth. Simple OHMS LAW... (Grounding Electrode? Ground rod(s) connected together. UFER  Ground,  foundation footing Concrete Encased steel rebar + Ground Rod(s) tied together creating ONE Grounding Electrode.)

The only true way to know what the soil to grounding electrode resistance is, is to have it measured by a person that is qualified.

NEC requirement for the soil to electrode resistance is pretty much useless. IF tested the soil to electrode resistance requirement is 25 ohms or less. IF higher than 25 ohms, then an additional ground rod is required. No further testing is needed. NEC code is satisfied. That’s why electricians drive two ground rods. No testing needed. Therefore no test documentation is needed  for the electrical inspector. A lot cheaper for the electrical contractor. Time is money...

( FWIW, IF tested the soil to ground rod may, for example, test 100 ohms. What are the odds driving a second 5/8" X 8ft rod will lower the resistance to 25 ohms or less?)

FWIW, IEEE recommends 5 ohms or less for a commercial electrical service’s grounding electrode.  

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The tech (30 year electrician and device repair man) was very clear, one path in for power and all connections or you risk creating a loop that encourages the lightening to travel around and exit after the damage is done. 

First I doubt he is a licensed electrician. He is more than likely just an electronic repair service tech. He may be very good at what he does. He is entitled to his opinions...

 Just a guess though for your experience at the time of losing  audio equipment from a lightning event was more likely from poor grounding of the shield of the CATV coax cable. Just curious, was you using more than one branch circuit to feed your audio equipment at the time? Or all of the equipment was fed from one branch circuit?

Jim

 

 

Welp, somehow things always get muddled. 

How so? 

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FWIW...

NEC, Article 90

Quote:

90.1 Purpose

(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. This Code is not intended as a design specification or an instruction manual for untrained persons.

(B) Adequacy. 

(A) Covered. This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance result in an installation that is essentially free from hazard but not necessary efficient, convenient, or adequate for good service or future expansion of electrical use.   

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"This Code is not intended as a design specification or an instruction manual for untrained persons."

Some people need to stop playing Electrician.

Roof top antennas and satellite dishes. An external signal power source is not at play, like a CATV or Internet only signal that is fed to a house by a coax cable signal provider company.

At the point , just before entry, into the house a grounding block is installed between the  CATV or Internet only providers coax cable. As I posted elsewhere in this thread NEC requires where it is connected, therein to the electrical service’s equipment GES, (Grounding Electrode System).  

Roof top antennas and satellite dishes  may use the same grounding block to bond the shield of the coax cable to the GES.  Language in NEC does not call it a grounding block though. Instead it is called a Discharge Unit. Google antenna discharge unit.They are not necessarily one in the same.  (FYI, the minimum size of the bonding ground wire required from the discharge Unit to the GES is #10AWG copper or 8 aluminum. NEC 810.21(H)). #10AWG copper wire, not to exceed 20ft in length... Is the #10 sized wire needed to discharge the static high voltage to Mother Earth or to divert a nearby lightning strike or lightning EMP high voltage transient surge to Mother Earth?  

(Food for thought. NEC only requires a #14 copper ground wire for bonding the grounding block to the GES for the shield of the coax cable for a  CATV or Internet only provider. FWIW the ampacity of an insulated #14AWG copper wire in free air is 35 amps.)

What are the differences between roof top antennas and satellite dishes and CATV or Internet only providers? For one the CATV or Internet only providers equipment is powered from a remote AC mains power system. Second is wind... Wind blowing across the surface of an antenna or a dish causes static electricity to build up on their surfaces.

( Static charge could be in the 1000s of volts) The Discharge Unit bleeds off the static charge to the GES, to Mother Earth. The Discharge unit also  will divert a nearby lightning high voltage transient surge to Mother Earth via way of the GES.

And yes bonding of the Discharge.Unit to the GES puts the shield of the coax cable at the same ground potential as the GES of the electrical service. That’s a given.

 As for this:.

A grounding block is required for any coaxial cables entering a home from the outside, whether from the cable TV provider, an FM or TV or Dish antenna as well. These ensure the ground potential of your antennas stays at the same reference level as the rest of your home outlets so you don’t have the possibility that ground on your antenna is hundreds of volts different than the house ground.   This was probably installed by your cable/Internet provider already.  

As for a  grounding block, used for the coax cable of a cable TV provider or internet only provider. Bonding the grounding block to the electrical service GES, is, hopefully*, at the same ground potential as the Grounding Electrode System, of the main electrical service equipment. (Reason it may not be? Poor and or corroded connections at each end of the bonding ground wire. Same for the F connectors connected to the grounding block.)  It does not guarantee there will not be a difference of potential from the EGC, (Equipment Grounding Conductor), at the wall outlet to the shield of the coax cable of the equipment it is connected to. Result, ground loop hum.  

*Reason for a difference of potential, voltage, from the shield of the coax cable  to the wall outlet EGC?  Resistance in the EGC connections from the wall outlet to the ground bar in the electrical panel due to poor and or corroded connections.. .If the wall outlet is fed from a sub panel add more connections because of the feeder EGC . Same problem can happen with the coax F connector connections as well).

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