atcomsystems.ca/forum Forums General General Telephone & Systems Information Lightening Stirke

I am pretty sure that he meant that a cloud covering the sun meant the possibility of a thunderstorm. I think it was more of an exaggeration of strange weather that can happen.

Bonding building grounds together is why they make shielded cable. To isolate the cable pairs from differences in ground potential.

Throwing a cable in the ground or in the air and punching it down on a Panamax "protector" isn't how it's done. People actually believe that this is all that needs to be done, but they are wrong, way wrong.

Amen, Brother EV, you are preaching the word on grounding and bonding. Ground the world round is only as good as the bond.

Okay, now pass the collection plate. :thumb:

KLD -- The one-eyed....

Agree

Ground Is Ground The World Around And James Is Not The Only Bond That Protects And Serves !

Yes it was an exaggeration. But electrical storms almost always caused problems. The earth's resistivity was so high that the current flowing through the ground found its way through the bulding to building conductors and zapping anything in its way. Even proper sheath bonding didn't help. I thought that beefing up the grounds at each building would help but it did not. In fact I probably made things worse. Once a common ground was installed the problem was no more.

I would have to disagree that the original bonding was proper because a 25+ pair cable sheath is the approximate electrical equivalent of a #6AWG conductor. If all bond clamps and attachments were the correct type and installed properly, there would have been no need to bond the buildings together. Doing that is not always the best thing to do in the event of an electrical fault, especially if there are separate electric services.

I am glad to hear that all worked out though. I am a former electrician so I am bit biased about doing things to code, and then I am also a Pr&^k about Bell System standards. Both take this subject very seriously and specifically address grounding and bonding as priority #1.

Check out the "Outside Wire Construction" category if you are interested in more discussion on this topic.

This is a subject that will be strongly debated until we don't have lightning anymore. If that happens, I guess we won't be here either!

Lightning according to NASA

Dec. 5, 2001: Lightning. It avoids the ocean, but likes Florida. It's attracted to the Himalayas and even more so to central Africa. And lightning almost never strikes the north or south poles.

These are just a few of the things NASA scientists have learned using satellites to monitor worldwide lightning . So if I where the obhhbe I would say drive your ground rods into the North Pole . My humble personal opinion . :thumb:

Just kidding !

The common ground is laid in a trench between all buildings. It is aprox 1" diameter of stranded copper and put in a bed of condacrete. It is about 350 feet long. From the ground cable, spurs go to each building and are a little smaller in diameter. They terminate in a copper plate 1/4 " thick and 12" X 3". From the copper plate, #2 AWG. goes to the equipment room and is terminated to all equipment. Also the electrical service in each building, there are only three, are bonded to this ground system. A company from Canada, was subbed to do the gob. They specialize in cell tower and antenna grounds as well as communications buildings when unusual situations are encountered. After they put this in, everything ran perfect. It has been four years.

Wow. That's some serious grounding and bonding. It must have been expensive!

I used to work for an elecrical contractor. We would install exspensive grounding grids for cell towers.

Different soils also effect the ground potential. Sandy dry soil is a terrible ground. Hardpack clay would be most ideal. I guess in florida if you drive the rod deep enough you would hit water and you would have a great ground. Hey, Is ligtning an AC or DC crkt. or is it both?

Yes, It was very expensive. All expenses had to be paid for the initial visit and the installation visit for 2 techs. They contracted local help to do the digging but the techs did the connections. All nodes and splices were blast welded together.
Soil types made a difference. They took several samples. They also took 3 sets of earth resistivity data and used the average for the design.