wifi4milez
Big Russ, 1918 to 2008. Rest in Peace
join:2004-08-07
New York, NY
 ·Verizon FIOS
 ·Sprint Mobile Broa..
 ·RoadRunner Cable
 ·BroadVoice
| reply to John Galt
Re: Will burying a feed line ground the CPE?
I have read that the lighting arrestors are not really effective, and that the only way to really protect the equipment is proper grounding. Any thoughts on that? Also, I could theoretically put a POE amp just below the omni to counteract the cable loss, correct?
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I like dogs, guns, and cheeseburgers. Whats your malfunction? |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
 ·CenturyLink
| Regardless of whether they are effective or not...you are still obligated to ground the system in a Code compliant manner.
An amp may or may not help you. Do a link budget calc and see what it shows. The preference is to NOT use amps...unless necessary.
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A is A |
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wifi4milez
Big Russ, 1918 to 2008. Rest in Peace
join:2004-08-07
New York, NY | Fair enough, how would you suggest accomplishing this task then if running the cable will be problematic?
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I like dogs, guns, and cheeseburgers. Whats your malfunction? |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| The Code requires that you ground the antenna where it enters the house.
You could also put the cable in PVC conduit from the "mast" to the house to keep it dry. You will have to seal where it enters and exits from the conduit to keep water from pooling inside the conduit.
As far as the loss issues..use sufficiently large cable to cut losses to a minimum.
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A is A |
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wifi4milez
Big Russ, 1918 to 2008. Rest in Peace
join:2004-08-07
New York, NY
·Verizon FIOS
·Sprint Mobile Broa..
·RoadRunner Cable
·BroadVoice
| Would I need to drill small drainage holes in the bottom of the PVC every few feet? I am still a bit unclear as to if this setup would disperse some or all of the lighting in the event of a strike (even when using arrestors). If not, there wouldnt be any point to burying the PVC other than aesthetics.
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I like dogs, guns, and cheeseburgers. Whats your malfunction? |
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John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
·CenturyLink
| Do a search and go back and read some of the recent postings on lightning.
There are a number of good references here...
Once you become better informed the answers that you are seeking will be readily apparent.
The Polyphaser site is good:
»www.polyphaser.com/ppc_ptd_home.aspx
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A is A |
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bito
Premium
join:2001-10-08
Atlanta, GA
| Why don't you mount the AP up with the omni and thereby eliminate all of your RF loss? Assuming the AP is PoE capable. Then ground the antenna/arrestor/AP at the base of the mast with a ground rod. That way, all you have to bury is the cat5 cable. I would imagine that 100' of gel-filled cat5 is a heck of a lot cheaper than 100' of LMR 
That's my 2/5 of a nickel anyways.
Caleb |
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wifi4milez
Big Russ, 1918 to 2008. Rest in Peace
join:2004-08-07
New York, NY
·Verizon FIOS
·Sprint Mobile Broa..
·RoadRunner Cable
·BroadVoice
| Thats a pretty good suggestion. Cant lighting travel down catv as well though? I would still need to use an arrestor prior to entering the house if I am not mistaken (thats fine by the way).
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I like dogs, guns, and cheeseburgers. Whats your malfunction? |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
| said by wifi4milez  :Thats a pretty good suggestion. Cant lighting travel down catv as well though? Yes, Lightning can follow any type of conductor anywhere. Since the CAT5 has copper, it is a conductor, It will usually take the least path of resistance, hence everyone trying to give it one and guide it away from our gear.:)
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bito
Premium
join:2001-10-08
Atlanta, GA
| reply to wifi4milez
Next to a beer, this is one of the best $3 you can spend:
»www.radioshack.com/product.asp?c···=61-2144
Up to 10kA current suppression, clamps at 60-90V. Won't handle a direct strike on it's own, but if your AP takes a strike and you have it properly grounded then it should be enough to handle any leftovers from the initial spike. Your AP will be in flames in a puddle on the ground, but this should keep you from blowing up the customer's router/computer/any-damn-thing-else-that-is-connected-to-it.
I was in the shop one night last month when we took a direct strike to our omni rig on the roof. It instantly fused the POS arrestor we had on our coax run and blew the radio, but it wasn't done yet. Apparently it had enough juice to come through the PoE injector, down the data cable into our switch, then proceded to blow a gateway (bits burned out over the course of 10 minutes, slowly the lights started to blink away and never come back), a server (through the LAN to blow the board and power supply, but the RAM and HDD were ok), our DSL modem, then over the phone line to blow out the filter. The building next to ours took a spike on the phone lines at the same instant that blew up their router and server, don't know if we sent that their way or not. Apparently it kept just enough voltage going through it to blow everything, and then when it was fully convinced it had enough destruction for one night, the whole damn thing when critical and the cables at the AP EXPLODED. Also, it blew the top off the omni and VAPORIZED a full foot of the metal element inside. It blew the damn connectors off of the omni side of the LMR. Blown off, as in loosened and then blown off and found on the ground. Funny enough, i redid the end of the cable with the same connectors and it works fine.
I was sitting in the same room with all the gear when it blew. It made a pop so loud that I couldn't hear out of my right ear for about 10 minutes. Oh, and it killed the big roll-up door, so I had to muscle my way out of there. I could have sworn something inside blew up. I didn't know what happenend until I realized my internet feed was tanked.
Needless to say, the next day is when we started looking for better protection 
Moral of the story: Take as many precautions as you can when it comes to lightning protection. Lightning is some crazy sh!t, and it hates your equipment
Caleb |
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public
join:2002-01-19
Santa Clara, CA
·DSL EXTREME
1 edit | said by bito :Next to a beer, this is one of the best $3 you can spend: » www.radioshack.com/product.asp?c···=61-2144I was in the shop one night last month when we took a direct strike to our omni rig on the roof. It instantly fused the POS arrestor we had on our coax run and blew the radio, but it wasn't done yet...the whole damn thing when critical and the cables at the AP EXPLODED. Also, it blew the top off the omni and VAPORIZED a full foot of the metal element inside. It blew the damn connectors off of the omni side of the LMR. Blown off, as in loosened and then blown off and found on the ground. Needless to say, the next day is when we started looking for better protection Moral of the story: Take as many precautions as you can when it comes to lightning protection. Lightning is some crazy sh!t, and it hates your equipment Caleb This is a graphic example of a design error. The omni should have been protected by an air terminal. Most of the current would then be diverted into ground instead into the equipment inside.
It is incomprehensible why some operators in lightning prone areas mount an omni at the very top and thus use it as a lightning air terminal.
With a little foresight path of a lightning discharge when a strike occurs can be fairly predictable. Just allow for 10-150kA current, with 30kA average for up to 100ms. |
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bito
Premium
join:2001-10-08
Atlanta, GA
| No kidding. Hindsight is wonderful though. It should have been ok (at least for the equipment), had our inline arrestor not fused shut and instead of diverting to ground it continued to zip through the coax. It was an old piece of junk evidently. |
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public
join:2002-01-19
Santa Clara, CA
·DSL EXTREME
| said by bito :No kidding. Hindsight is wonderful though. It should have been ok (at least for the equipment), had our inline arrestor not fused shut and instead of diverting to ground it continued to zip through the coax. It was an old piece of junk evidently. What was used probably was a surge suppressor, not a lightning arrestor. The only real arrestor used on power lines is a large spark gap.
Other equipment or structures need to be protected with a grounded air terminal for the direct strike, and surge suppressors for voltage rise effects due to the lightning current in the main protection circuit. |
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