lightning storm

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.)

Nope. 

Lightning strikes from coax or network connections aren’t necessarily from ground to ground.  They seek ground potential, but they are not necessarily carried in by the ground conductors. 

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.  

This is a reason why I specifically do NOT recommend grounding Ethernet "surge protectors."  Best to deny a surge a path via isolators than to allow a low voltage current path which may also convert common mode to differential and enable the passing of a surge downstream. 

In the case of an outside surge coming in from other than the power lines, the series mode protectors have the edge as instead of encouraging the surge path they deny it, but only on the hot wire I believe.  

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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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. I did not have the coax going though a surge protector which probably was the issue as you describe. Of course the lightening went through the HDMI and fried my video processor, then projector and went out the wall through a surge protector which did not trip. So now all power runs through one plug via the P-15 and everything is streamed in 4K, it is all air gapped. Now I know for sure it’s safe, and I double check the Weather Bug every time I fire it up! 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. 

@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.  For the record, I recommend the use of an outdoor coaxial surge protector mounted ON the grounding block. 

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.  

A coaxial surge protector is there for cases when an electrical surge is present on the inner wire, diverting that excess voltage and current to ground before entering your home, which is why it’s best on the outside and on the grounding block itself.   They are imperfect but they do limit the fallout radius of a lightning surge.   Sometimes these are installed by the cable TV / Internet providers but usually inside on the modem. 

For further reading check out sites devoted to ham radio operators.  

If you have an antenna mounted in the attic a ground block is not required.