Replies

1. 
   Matt | Dec 12, 2009 06:58pm | #1

   here is some hindsight for ya.... When we start getting those kind of lightning strikes we start unplugging stuff like TVs and computers.

   BTW - that pic you have there - is that the "go ahead punk - make my day" scene? Or am I a decade or 2 off?

1. 
   Nuke | Dec 13, 2009 06:18am | #4

   It is Harry and that scene. One of my all time favorite movies.

   BTW, that lightning bolt came without notice. It was dead calm before it happened. No rain, no storms, no distant sounds of thunder. Just BAM! :)

2. 
   DanH | Dec 12, 2009 10:55pm | #2

   I would bet that most of your damage came in on the cable and phone lines, not the power line. You should at least have some sort of surge protector on the incoming cable line (not counting the lousy one the cable company may provide), and on the phone line as well, if it's connected to anything more expensive than a $69 K-Mart phone. It also helps to add a separate ground wire to the cable modem, as generally they aren't grounded through the "wall wart" power supply.

   Grounding (to "real" ground) isn't really a requirement for surge protection. Rather, what's needed is to limit the voltage differential between the various wires connected to the equipment. Your better surge protectors include both MOVs to ground and MOVs between hot and neutral, to limit these differentials. But you also need to limit the differential between cable wires and power wires.

1. 
   Luka | Dec 12, 2009 11:29pm | #3

   Dan,

   Reading his story, it sounds to me like the lightning was hitting the ground, and since the granite is so close to the surface, it was running/dissipating TO the grounds on the houses in the vicinity.

   Kind of a backwards kick in the pants...

   Howinheck does one protect against that sort of backwards surge ?

1. 
   Nuke | Dec 13, 2009 06:24am | #6

   This is exactly the case as I was told by the electrical coop and telephone power systems guy. I have no idea how I am suppose to protect from that entry point especially when I had no warning that bad weather was coming.

2. 
   DanH | Dec 13, 2009 05:29pm | #8

   Certainly there are some scenarios you can't protect from, and there are indeed many way for the surge to enter the system.

   The shallow granite (which is an insulator, I suspect) combined with relatively dry soil would prevent the ground from equalizing, and a strike in one location could raise the potential of the ground in that area relative to other areas. This would then cause surges to radiate out over phone, cable, and electrical lines coming from that area, in the process toasting equipment in the area connected to those lines (in addition to less severe damage to distant equipment).

   But sometimes it's just the massiveness of the strike. A lightning bolt induces voltage/current in any parallel metallic objects nearby, including wires, pipes, metal support posts, etc. This can result in damage even to isolated equipment.

1. 
   Nuke | Dec 14, 2009 07:44am | #9

   I am wondering why the two flat panel HDTVs were damaged yet the surge suppressors exhibited no damage. Not even their breaker/fuse were compromised. I would have thought this would have been the case considering how many joules they were rated for compared to what the bolt delivered.

   Same thing for the three computers, which had their network interface chips on the motherboard damaged. The data network for them runs through Ethernet switches to a router to a cable modem, which runs through a surge suppressor coax interface then outside.

   I've found no visible evidence that the surge suppressors were even engaged let alone exhibit a change in their ability. Maybe they are hollow and nothing more than a power strip.

2. 
   Nuke | Dec 13, 2009 06:22am | #5

   The flat panel HDTV's were
   The flat panel HDTV's were connected via satellite equipment and had no telephone or cable connections. The Sony PS3 had no telephone or network connection (used for Blu-ray playback not online gaming). The DirecTV HD DVRs that were NOT damaged were connected to the telephone lines. The three damaged PCs were connected to the home data network via the cable modem, router, and switches, which were also damaged.

   BTW, the cable coax runs through the surge suppressors as does the telephone lines plugged into the HD DVRs.

1. 
   Luka | Dec 13, 2009 12:40pm | #7

   If this particular kind of 'strike' were the 'norm'... then I would suggest a fusible link.

   But this is backwards from the norm, and it you put in a fusible link, that will negate the protection it is intended for, in the first place.

   Peculiar.