atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Outside Plant OSP Construction grounding between buildings

I have a 50pr cable carrying phones from a building 300 feet distant from the NEC EliteIPK phone system installed in my building. This cable is buried (about 4 feet) and in plastic (PVC?) electrical conduit. The pairs are protected at both ends with Corning 3B1E protectors which I believe are gas-tube type. We have continuing problems with cards in the IPK being damaged because of lightning. The shield on the 50pr cable is grounded on both ends. I have always understood that it is to be grounded on one end only. I have two questions;
Should the cable be grounded on both ends and should I replace the current protectors with Solid State types?
I appreciate your hosting a FREE service such as this board. I have read many of your responses and deem you to be very knowledgable and "to the point". Thanks.

The 3B1E modules are carbon block, not gas tube. You may want to replace them with 3C1E's to provide gas tube protection. Then, provide secondary solid state protection through the use of ITW units or something similar. These should be installed closest to the equipment. Yes, a #6 ground should be connected to both ends and bonded to the building's metal framing or electrical service grounding electrode.

definatley need the secondary

we cabled two buildings for a guy that refused to pay for secondary , he felt primary would be more than adequate (he had electronics background )

so we sent him a letter advising our concerns and proceeded with the install

two storms , two billable service calls and 30 bad ports later it was "how fast can you get that stuff in ? "

never lost a port after that

BTW welcome to the board

who says its free ?

stick around and help out

I'm sure you have a answer one of my need someday

Ed, thanks for the reply.... I have two additional questions relating to your post. 1. You said to replace the protectors with gastube... why not solid state? 2. What is an ITW unit... and does it go on the equip. side of the current protector box?
As to the FREE comment.... I have 40 years background in mainframes, PC's, LAN/WAN, and DataComm. If I can be of service, please ask.
john

Ill let ed handle the gas tube vs solid state question

heres the ITW lynx site they took over the panamax line

Well, you certainly can use solid state modules if you like, but they are significantly more expensive. In my experiences with using them, I haven't noticed any notable improvement in protection levels. It seems that gas tube does a good job of providing property & personnel protection while taming the surge. The secondary Panamax (ITW Linx) units are then able to do their jobs as secondary protectors. Yes, these units do connect on the equipment side of the building entrance terminal.

On the secondary, check for the clamp voltage, especially if you are running digital circuits through it.

My $.02 worth.

Ken, Ed, et.al,

After talking to sales engineers and techs, the recommendations are....
replace the carbon block primary protectors with either gas tube or solid state and provide secondary protection with ITWLinx up3 devices.
We have fiber buried along with the 50pr copper running to the remote building. I have a quote to place a KSU at the remote building and tie them together with fiber. I know this would eliminate the problem but the cost is around $6500. It looks like doing as everyone suggests with protecting the circuit would cost around $2500.
My question is, if adding a second KSU and connecting the two with fiber would provide 100% protection, what percent protection would I get with the other alternative?
john

Since its bests guess I would say PROPERLY done the gas tube primary and itw linx secondary would be in the high 90's for protection,

you need to be sure your gas tubes are properly grounded and you need to bond the 50 pair

Would fiber be 100% ?

Nothing is warranty, by who?

If you put proper primary and secondary protection you will be fine.

If you match proper protection to the source you
you are treating it will be fine. (clamping voltage/proper grounding )

You must take into the picture what the voltages/current of the station ports are rated.
What the voltage is when ringing current is applied etc. IF - IF - IF.

If you leave just one "IF" out of the picture, then you are screwed.

I would be very careful not to build a ground loop at this site. (another situation).

When you leave one little crack in a roof, the roof will leak.

You must look at "ALL " elements as one is just as important as the other.

Good luck. Its FRIDAY the 13th.
"

yes

How about the power fact after it leaves the fiber ?

Fiber is a to b.

There are other elements at the outer building that you have to consider. Right ?

They all have a effect even thought fiber is being used.

Fiber is a transport of the siginal from the ksu
to keysets at outer bldg.

If a electrode takes a strike its not fiber
(antenna,switch,router,security system are all
common to power)

I seen it happen all is protected, wrong, every element was not was properly protected and it must be.

Ive seen lightning punch a hole in the roof and use the bldg steel as a path and take out everything electrical but that has nothing to do with connecting two bldg s

as far as the path between blogs then yes fiber is 100%

To sum it up, like everyone has pointed out, do it right and you should come out okay.

Fiber is glass. Non-conductive. But what is on each end is power driven. Therefore the issue.

Skip has seen what the true power of lightning is. No matter what you do, if lightning wants you, IT GETS YOU !!! But you can reduce the risk by doing it right.

Cost of this project can be somewhat scary but what will the long term cost be for damaged equipment and lose of production?

Good Luck.

Bravo---Thanks Ken well put.

Ed, I'm going to steal this, sorta. I was taught that you should NEVER ground both ends of a cable shield, if they were in different buildings because of circulating ground currents caused by differences in building grounds. Comments, education, whatever? And anybody else, jump in here, this should be anm interesting discussion! John C. (Not Garand)

Dunno, John. All that I've ever followed was Bell System's Blue Book of Construction Standards. I am sure that installation standards may vary throughout the country. Technically, if the buildings' electric services are bonded and grounded properly, I would tend to think that a ground loop would be a moot point.

I will agree that I've taken apart sheath bond connections in splice closures, especially on long aerial runs, and have seen some minor sparking. I always assumed that this was simply due to voltage induced from the power being carried on the same pole run. Since aluminum is a fairly poor conductor, I figured that was the reason. Even though it was bonded, it could still pick up induced AC.

I think John has a valid point. Even with properly bonded electrical services the shield would be another parallel current carrying path. Whether that presents a problem is another matter though.

I do know that the specs for a service from the pole to an indoor terminal, the building side shield should only be bonded to the stub splice closure (if used) so it ends there. The terminal is bonded to the electrical ground but not the shield. Reason being what comes from the outside (lightning, power crosses) stays outside.

You would be surprised how many Verizon guys don't know this.

-Hal

I agree with both Ed and Hal. Bell always wanted grounding AND bonding. This may have been due to the lead sheath days. The ground loop is a fact, even if we were taught that "ground is ground the world 'round".

I have "cured" problems by "un-grounding" (Is that a word?) a cable on one end. In the early '90s Sprint started the isolation of C.O. grounds and bonding everything in a C.O. to a "PANI" grounding bar (Producers-Absorbers-Neutrals-Inductors). This was during the era of changing from mechanical/analog to digital switches.

So, by current standards at Embarq, the sheath is not grounded to the same grounding point as the C.O. protectors, the grounds on the outside plant are bonded to the MGN, and the C.O. has a separate grounding field. You will find this consistent with RUS as well.

Ed, your box. Hal, your code book. John, I'll have to e-mail you later.

There are two issues here - (1) Grounding for safety and (2) Grounding for performance.

In the old (BSP, GTEP) days of Panel, Stepper and XBar the equipment was so robust that performance was never in doubt. The emphasis was on safety - hence grounding both ends of a cable.

With digital systems, performance suddenly becomes important. When you're dealing with a 3 or possibly 5 volt difference between a "1" and "0" then a 2 volt difference in ground potential suddenly becomes crucial. This applies to both TDM telecom systems as well as Data products.

I recently saw an interesting problem. A customer had two buildings, less than 100' apart. The computers in Building "A" could log on to servers in Building "A" but not to those in Building "B" and vice versa. It turned out that the contractor had not followed the EIA/TIA 607 spec - He had not tied the ground bars in the two closets together. The two buildings were served by two different power generating stations. When it was tested the ground potential was found to be over 3 volts! As a result, each building could function independently but not together as a complete network. A 2/0 cable was pulled between the two buildings and the problem went away.

I should also say that the data tie between the two buildings was a Cat 6 cable. Because of the short distance between the two sites, it was felt that the expense of fibre was not justified. If an optical feed had been put installed, I believe the problem would never have been discovered - At least not immediately.

Ken, I too was raised on "ground is ground, the world round" - but I've come to believe it just ain't so anymore.

Sam

I have done sound jobs that required multi buildings to tie together for public address. I had 3 hangers (about 1500' apart) at an airbase that I measured 70 volts between grounds. Fried several amps on that one. I have also seen times where the ground difference melted the shield of cheap balanced line cables run between systems.

metelcom's comment is the SCARIEST.

Thinking: Air Force Base (and I suppose commercial) runway, taxiway, hanger foundations, are at least 18 inches thick, in my limited experience. I know that buildings bolted to concrete slabs are assumed to be grounded, but I don't buy it! I know of no concrete, or rock for that matter, that conducts anywhere near as well as iron, never mind copper! The only reason it's gotten away with is the HUGE effective 'conductor'

But, try to get permission to drill through the slab to dirt. Good Luck! Never mind the relatively poor ground under the slab, especially in low rainfall areas.
John C. (Not Garand)

Gentlemen,
I'm a newbie to the forum but a long time browser. I've got a question, and Im sure its been answered somewhere in this thread, but I didnt see it exactly.Guy called me last week to splice some cable at peds for townhomes, 25pr in and 4- 6pr out. I bonded all 5 sheaths together in ped but didnt tie to ground rod. Then terminated 6 prs at nids, grounded sheath, and tied to ground at nid.Assuming 25 pr is sheath is grounded at mdf, is the the right way? Not sure if the ground feeds at ped and nid are origionating from same ground rod, theyre only 50-75' apart.

Thanks,
Gene Hudson
ACT,Inc

Gene:

That sounds like the right way to go, but you really should have a ground rod at the pedestal.

Also, the pairs shouldn't be hard-spliced together; the 25 pair should terminate on a block designed for mounting within the pedestal. The 6-pair drops should only connect to the necessary number of binding posts on a per-address basis.

How come you are doing this work? Shouldn't this be the LEC's responsibility or is this on private property?

Ed,
Im sure this is private deal, townhomes and such,theres a headend bldg. somewhere on site where CATV and phone come in and the guy that hired me(underground utility contractor) seem to be responsible for cable placement and connectivity past that.I agree, the pairs shouldnt be dedicated in the ped, but thats the way they want it, and they are only having me splice 2 pr on each 6 pr thru.There is a bare copper #6 ground coming up in ped, I just didnt tie to it.Thanks for the reply. Gene

There is a bare copper #6 ground coming up in ped, I just didnt tie to it.

What do you think it was there for? Was the ped located together with a CATV ped and an electrical transformer? We always make sure all three are bonded together to the utility provided ground rods at the transformer.

I wouldn't have bonded the 6 pair sheath at the NID. NID ground should go to the electrical ground, not a separate ground rod if anybody is thinking of that.

I had 3 hangers (about 1500' apart) at an airbase that I measured 70 volts between grounds... I have also seen times where the ground difference melted the shield of cheap balanced line cables run between systems.

Yup, that's what I'm talking about.

I know that buildings bolted to concrete slabs are assumed to be grounded, but I don't buy it! I know of no concrete, or rock for that matter, that conducts anywhere near as well as iron, never mind copper!

Believe it. It's called a ufer ground after George Ufer who invented it many years ago. Connecting a ground wire to the rebar that is inbedded in damp buried concrete such as the footing around a building provides a much better ground than any ground rod, even several tied together. Matter of fact it's so good that the latest NEC now requires in all new building construction that a piece of the footing rebar be left stubbed out and exposed so it can be bonded to in lieu of ground rods for the electrical, telco and CATV services.

-Hal

Gene:

I agree that you sometimes have to do what you are told since there's really no enforcement body in place to dictate otherwise with outside plant. I'd still go ahead and tie into the #6 that's there to the pedestal's bonding bracket.

Hey, look at it this way: At least you made the effort to get a second opinion.

Thanks Guys. I guess my point was( athought I didnt express it) is that Ive always heard that grounding cable on each end to seperate grounds made an antenna. I did a college in Pa. and the elec. engineer would only let me ground the MDF end.

gelehu....therein lies your problem.....

MGN ground is there for a reason. What if you lose the grounded sheath between the end of the run and the MDF? Buried plant inducts little voltage, multiple grounds drain it over short distances. Why not ground? :shrug:

Why then doesn't aerial cable running for miles below high voltage lines not cause problems? Because it is grounded and bonded at intervals or every power pole that has a ground on it.

What does an electrical engineer know of OSP? Let him go hang a transformer! :p :bang: :toothy:

Oops, forgot to click 'add reply', duh-uh!

Hal, the info about the rebar stubout being required is 'file-away' stuff. Now if the contractors will really do it!

Ken, did you really mean "hang FROM the transformer TERMINALS"? John C. (Not Garand)

Now if the contractors will really do it!

They have to. If the ground wire is not connected to it the EC gets a red tag. Red tag means no C of O. No C of O means the building isn't finished and the people can't move in.

Of course there were hotshot, know-it-all general contractors who said screw stubbing out the rebar so that the wire could be connected. They were made to dig down to the footing, jackhammer the concrete to expose the rebar so the EC could cadweld the wire to it.

There is justice.

-Hal

I am getting ready to install Porta Systems model 525, 5-Pin Building entrance protectors on some Cat 6 lines that run between two buildings in PVC. Will use Reltec 5 pin gas modules in these.

Do I also need to have a secondary Linx protector in place in the lines?

Thanks


Porta Systems Model 525
5-Pin Building Entrance Protector

If that CAT6 is for data I'm not sure those Reltec modules are suitable nor is the block that holds them.

Is there flooded CAT6 for direct burial available?

If you are talking voice (and I would ask why the heck are you using CAT6) then a primary protector is necessary where the cable enters the building with a secondary protector near the equipment to be protected.

-Hal

I've never seen anything rated for use with a CAT6 circuit in a five-pin module. Protected building entrance terminals aren't rated for any "category". They are outside plant protector modules and have nothing to do with data cabling. We really are talking about two completely different industries.

Even more so, I have not seen anything above CAT5e with regard to cable. This might be an accident waiting to happen. Sounds like a job for fiber and a pair of transceivers.

The Cat 6 lines were put in during construction so we would be able to talk to each end as we worked installing fiber between the buildings.

It was installed just for voice, not data.

We now have fiber carrying both our data and voice. The voice connects our NEC switches.

Problem is, the fire alarm people needed a voice line, two in fact, that did not go through the switches so they grabbed some of the Cat 6 lines and hooked up their voice lines on them.

They did not install any protection on the lines and now we are to go back and do so.

Tom

Tom:

You will be fine with something as simple as a standard signal circuit protector or network interface device. No need to worry about the category rating or to spend the ridiculous amounts for the C5 units or higher. Just make sure that it's connected to a good grounding source.

Thanks Ed,

Have a couple of NID's on hand so that sounds like a good option.

Tom

Good Afternoon Gents,
Just recently started a splicing job.The customer was in a jam and I explained to him I could put wire together and get it to the right location but I didnt call myself a splicer. I want to do it right and have a few questions.
1)Cable is direct buried filled 100pr,25pr,6pr.
Theres a #4 bare copper coming up in the NIDS,Peds and the head end.What size ground wire should I be using for bonding and tying to these incoming grounds for respective sizes?Stranded or solid?
2) Hes asking to have cable and grounds tested according to ANSI/TIA/EIA 568-B, NEC 770, and IEEE 802 standard. Im not even sure this applies to OSP but if it does Im assuming I can do it with a cable certifier although Ive only ever certified inside cat5, 5e and 6. The head end is terminated on Porta systems with 110 term. and the far end (6pr) nids are on single pair protectors with binding posts. In my experience with splicers Ive had them talk out pairs to verify. By the way, this cable is for voice only, the high speed stuff is going on coax.
Thanks in advance for your help. Gene

Someone better tell the cable company that.

Use bullet bonds on your cables and bond them all to a the common ground bar, in the terminal. Then ground the terminal to your #4 with either #4 or #6 soft solid copper. To test your ground, go to a good ground source, as power ground and see that there are no more than 5 ohms difference, you really should see zero. Finally bond all grounds together. No you don't certify voice cable, simple continuity test are fine.

There are some pretty good OSP folks here and will correct anything I've missed.

Bill,
Appreciate the info. Ive got sheath clamps on all my cable sheaths but it would seem with #4 or 6 ground wire its not going to work on a 6pr sheath ground. Typically each ped has a 25pr and 10 6pr UG coming in. Do you think the EIA/TIA spec is pertinent to OSP filled cable. Ive already talked out some of the pairs and Im sure they are ok. Thanks Again, Gene

Your bullet bonds, or sheath clamps, will terminate in the bonding bar of the terminal, the ground will terminate on the bonding bar not the cables. No the cable cert is not for OSP cable.

This falls under the section called common sense, but.. Before you do a resistance check between 2 'grounds', ALWAYS do a voltage check, and expect the worst. It'll probably be fine, but it only takes 1 snap, bang, boom, or puff of smoke, to bring reality to the forefront! (Whoa, 1st time I've ever had the chance to use that word.) And, yes, that's experience speaking! John C. (Not Garand)