Problem loosing ethernet on modem do to lightning

[goop]

I work for a wireless cable company, which runs a hybrid system. Recently, I have noticed the vast amount of modems coming into the whouse with the same problem. I personaly am not an electrician, yet do want to rectify the problem and loss of money for my company. What would be the best procedure for grounding our antenna/tower?
Also, I have reached hybrid systems and recieved a pdf file in regards to proper installation, which intails using a (antenna discharge unit) on the main lead. It proclaims to follow suit to section 810-21, yet how does one find this info, if one is not an electrician? "I've seen in another forum here on the topics regarding grods which we use for the tower or telscopic rhon pole", but as of now we only use rg6 60% messengered cable for main lead... that messenger is the ground line for the lead? please help... and thank you... Gary

[ August 29, 2003, 04:36 PM: Message edited by: goop ]

 

[bennie]

Re: Problem loosing ethernet on modem do to lightning

goop: Consult with a local Ham Radio Club. Also buy the ARRL Antenna book.

 

[hbiss]

Re: Problem loosing ethernet on modem do to lightning

Gary, you are all over the place with a description of your installations- towers, messengered RG/6, wireless cable company. A little bit of everything. When I hear "wireless cable" I think of DSS. Where does the messengered RG/6 come in?

How EXACTLY do you operate? Satellite? Terrestrial microwave? Cable strung on poles? All of the above? How is a subscriber supplied? What do you provide? Explain more fully and maybe I can help.

 

[jrdsg]

Re: Problem loosing ethernet on modem do to lightning

i'm not an electrician either, but this sounds like a good opportunity to bring one into the loop, perhaps even an engineer.

no harm throwing a few hours at the right kind of help.

james

 

[goop]

Re: Problem loosing ethernet on modem do to lightning

Sorry hbiss, we work with a microwave connection.
We install towers and poles. The rg6 comes in various ways depending on the customers wishes...usually one of three ways through the attic, through crawl space, or through the exterrior wall to the modem/ tv... Yet we run wireless "line of sight, microwave signal."
Hope this helps...
Ps. in the progress of finding a solution... there's a new company that is sending me a few new groundblocks which *** power, but also act as a circuit breaker, protecting the customers home..
if interested..1-800-433-8775... ask for terry french.

 

[dereckbc]

Re: Problem loosing ethernet on modem do to lightning

Gary, to answer you question of how to ground a tower?

Simple you build an electrode system of either a rod, radials, ufer, or ring. Each leg of the tower is bonded to the electrode system. In addition the tower electrode has to be bonded to the AC service ground to equalize potential difference. It is required by code.

To answer your question how does one obtain a copy of NEC 810?

Buy a copy of the NEC 2002. Check www.nfpa.org

From what you describe your installation does not comply with code. I am not suprised you are loosing modems.

Your RG-6 has to be bonded to the AC service ground before it enters the house. I also advise a ADU at the point of entry bonded to the service ground. The messenger does not comply.

[ September 02, 2003, 10:37 AM: Message edited by: dereckbc ]

 

[hbiss]

Re: Problem loosing ethernet on modem do to lightning

Ok, now I got the picture.

Dereck is right on target. I assume though that your "towers" may be a pole on the roof or an actual tower out in the yard with messengered RG/6 running overhead back to the building.

Keep in mind that the NEC is only concerned with safety and the requirements are there to protect life and property. Consider them the very MINIMUM you need to do but they won't necessarily keep your modems from being damaged.

For instance, the NEC only requires that the shield of the coax be bonded to ground where it enters the building. That doesn't prevent overvoltage on the center conductor. You are on the right track with the power passing surge suppressor ground blocks.

Grounding and bonding the pole or tower and locating the coax entry point with the ground block/surge suppressor next to the service entrance where it too can be properly grounded will go a long way in helping your problem.

I think your biggest problem is going to be locating the "tower" and cable entrance to facilitate this. There is no quick fix here. It's going to take more time and material because your installers can't just go through the attic or wall wherever it's convenient. Your boss isn't going to like the added costs. Also, what's aesthetically pleasing to the owner is usually not conducive to a proper or safe installation so expect alot of resistance all around.

 

[tom baker]

Re: Problem loosing ethernet on modem do to lightning

"For instance, the NEC only requires that the shield of the coax be bonded to ground where it enters the building. That doesn't prevent overvoltage on the center conductor. You are on the right track with the power passing surge suppressor ground blocks" The nec also states impulse supressor has to be listed. I did some research and found very few listed impulse supressors, most are not listed, but they don't ahve to be as the NEC will allow the coax sheath to be bonded instead. However, use a good quality impulse supressor, such as Polyphaser, and you'll have few problems if the polyphaser itself is properly bonded.
Polyphaser has great publication "The grounds for lighting and emf protection", check there web site, and also you will find a lot of white papers on radio and coax protection.

Heres the key point in radio and coax grounding. Keep the lighting energy outside. connect the outside lighting and bonding grid to the power system ground system at one point, ouotside.

 

[hurk27]

Re: Problem loosing ethernet on modem do to lightning

Keep the lighting energy outside. connect the outside lighting and bonding grid to the power system ground system at one point, ouotside.

This is a very missunderstood grounding requirment.
It is very simple if you provide a better path for lightning outside of a house to the service electrode/ POCO's grounding then the lightning will leave the equipment inside the house alone, wel most of the time. I had a customer that had a house on a hill and every time there was a lightning strike close by him he lost all of his modems and phone equipment. when I looked at the installation. the phone drop wire was bonded to a 2' ground rod and that was all. from the looks of the powercords on the computer it looked like the lightning surge was trying to go to the neutral in the circuit supplying the computer. this was because the neutral was a better path than the 2' ground rod of course along the way it passed through the modem and the power supply for the computer and a few other things. but after rebonding it and the cable TV to the main service electrode he had called me to let me know that he's had two more strike's and nothing blew out. now after a year and a half he hasn't had one bit of problems with it. Glen should remember this because I had asked him about who to call about the way the phone company was grounding the drops.