1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Lightning

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by johnnytex, Jul 27, 2013.

  1. ticmxman

    ticmxman Legend

    282
    1
    Aug 27, 2007
    Just wanted to add to this conversation that an often overlooked entry point are your data cables coming into your house. I've seen a lightening surge travel down a coax cable for a cable modem, fry the modem, exit the modem through the cat5 wiring, then travel down the cat5 wiring and fry everything connected to it. For this reason, I think it would be wise to surge protect the cable modem coax, teleco, and any Ethernet cable coming from outside - before any of those are connected to the rest of your home wiring. Of course these lines should all be properly grounded too. This is in addition to the whole home and local ups protectors others have described.


    Hmm now that you mention it, I have switched to Comcast Internet and while the coax is connected to a ground block and the modem power is plugged into UPS the coax is not connected to a surge protector. I think I will fix that today, thanks dueport.
     
  2. DornoDiosMio

    DornoDiosMio New Member

    7
    1
    Jul 17, 2013
    Texas
    That is an excellent point dueport. Our recently installed DTV system was done without proper grounding. While the installer did ground the coax to the ground rod, he then ran it almost 60 feet from the ground rod around the outside of the house before finally entering the attic.

    To make matters worse, the wiring he used was 2 Coax lines fused together along with a ground wire also fused to one of the coax lines. Potentially, causing a lightning strike at the dish to jump across the coax prior to reaching the ground. This may not be an issue by itself, I'm just not 100% sure.

    However, if lightning happens to strike the 60+ feet of wire on the outside/roof area of our home before it enters the attic, it will go both ways down the line and straight into our home.

    Obviously the odds of such an occurrence are not particularly high, but, the consequences could be catastrophic.

    So, do you think they will willingly come out and fix it? I initially suggested they ground the system in the attic, where several other things are grounded. However, I was told by the installer, that the supervisor won't allow them to ground the system to anything but the ground rod. I can't believe that is actually true, especially when NEC guidelines state the entry into the home should be as close to the ground point as possible. Not 60+ feet away, while traveling across your roof.

    Thankfully we are still within the first 72 hours of service, about 48 hours in at this time. So, in my state you can back out of any contract within 3 days, but, I'm hoping I don't have to use that as leverage to get them to re-wire this properly.


    Sadly, I didn't realize the issue during the original installation, as I'm not fully aware of electric codes and I fully expected the installer would have been properly trained. Any opinions are welcome.

    Also, should I call the installation company, Multiband, or call DirecTV directly?

    Thanks a ton!
     
  3. TomCat

    TomCat Broadcast Engineer

    4,153
    100
    Aug 31, 2002
    So there's a real testimonial for the UPS. (not!)

    Apparently they do not make us all that invulnerable to power surges. I think you have to be completely on the battery side for protection there, because if not you are tied to AC ground which can swing wildly when lightning strikes, even if that strike is hundreds of feet away. Pro UPSes do exactly that (isolate the load completely from power ground).

    Also, if signal ground is tied to AC ground in the DVR, (even if you are fully on the battery side) the difference in voltage potential on a RF cable shield vs DC voltages present in the unit can also be significant enough during a close lightning strike for too much current to be drawn, which is why RF cables should pass through isolation via the UPS also. The problem there is that RF ports on a UPS are typically only going to pass UHF up to 890 MHz because they are designed for OTA antennae, which means RF from DBS won't pass through them making them pretty useless.

    And that is why grounding the RF cable using a ground block and some #6 wire to an 8-ft ground rod is really the only thing that will give you a fighting chance, and even that is not a guarantee. Cable companies compel their installers to comply to this for liability purposes, but it is not rigidly enforced. In my experience, DBS installers are even worse; they will just skip it if they can get away with it or if it might present a high degree of difficulty on a hot day. The odds of them getting charged back for not doing it are literally about the same as the odds of being struck by lightning.
     
  4. peds48

    peds48 Genius. DBSTalk Club

    19,924
    1,055
    Jan 10, 2008
    NY
    What type of dish do you have? a dual coax cable with ground is approved by DirecTV to use a proper way to bond the dish. It sounds to me that your system is properly grounded by your description
     

Share This Page