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

I work for a small independent telco, and I have a question about bonding a service drop to the power company's ground. In our area, I see a lot of new construction of homes where the power is installed underground in conduit and runs from a nearby transformer to somewhere in the basement, usually an interior utility closet, or on the other side of the building from where our demarc is. The problem with this scenario is that it is hard to find a power ground to tie onto. There is no point at the site of our demarc on the outside of the building to tie on to (as the power is buried below grade in conduit). How are we suppose to make the connection to a power ground? I do not believe we are to run a ground wire more than 20 or so feet inside of a house and even if we did, there is nothing to tie onto w/o opening up the power panel and running a ground wire into that, which I believe is a no-no as well. Not sure though. I cannot tie to a water pipe either, as nowadays, most of the plumbing and water pipes are all plastic or PVC. What is everyone else doing to solve this? Have the electrician wiring the house install some sort of bus bar to tie onto?

If I am understanding you correctly the power runs from outside then under the slab and up to the panel in the interior utility closet. The correct way to run the telco and CATV would be in a separate conduit (at least 2") that follows the same route. Your NI or NID would be located next to the panel in the utility closet. This is what I would strongly advise you to do (or require) for all further construction.

As for now you do not mention whether your drop is aerial or buried or if you are there during construction of after completion so it's tough to advise further. Other questions I have are where is the electric meter located, and are these single family detached homes or attached townhouses with the meters for all units at one end of the group outside?

Have the electrician wiring the house install some sort of bus bar to tie onto?

Actually the 2008 NEC requires exactly that. Whether your jurisdiction has adopted the 2008 code is another matter.

-Hal

Thanks for the response. The drops we install are buried, and our company policy for residential homes is to mount the demarc on the outside of the premises. Makes it easier to access for troubleshooting. Also, aren't we limited to only running drop cable 20' inside of a building? The power meter is located on a pole next to the power transformer out by the ROW/Utility Easement. There are many instances where we are not present during the power install or are even unaware that a dwelling is going up until its too late to go in w/ the power. I guess I am just looking to see what others would do in these situations.

Hal is the codes guy, for sure.

Now, in your situation the NID/Demarc, whatever you want to call it, is always best (residential) to be outside. As the electric meter is ahead of the service, you have no choice but to do a local ground unless.....

Yes, the drop wire is restricted (gel filled) how far you can penetrate inside the building. But you can run ground wire. Run it to the power panel, have "sparkie" hook it up.

This is when your boss (or you) need to stop by when you see the house going up or see sparkie having coffee...fill them in. As a small town independent company you or your business office people have to be in contact with the new owner, make sure there is a mutually agreed upon location for the Demarc and have sparkie run a ground to that location.

You see, there are options.

Good luck.

Also, aren't we limited to only running drop cable 20' inside of a building?

Actually it's 50 feet but if you are running it in conduit under the slab it's considered outside the building, so any length is OK. But if you are locating your NI outside you wouldn't be running BSW inside anyway.

I think the only way to get your ground given what you just told us is to require the sparkie to provide a bare #6 out through the side of the house. I'm assuming that he does the prewire and dumps an (unfortunately) CAT5 or bunch of CAT5's out the side of the house someplace. He needs to provide you with the ground also which can come from the panel or from whatever grounding electrode he is using- whichever results in a shorter run.

-Hal

Regardless of how the electrical service is configured, there must always be a #6 copper conductor run from the service entrance panel to a grounding electrode (usually a rod) or two. The location of these electrodes must be installed in permanently-moist soil, so it's not likely that they were driven before the slab was poured.

It's still legal to bury these rods in a horizontal trench that is at least two feet deep. In your area, I'd imagine that the soil is probably too hard to drive rods, so the electricians may have placed these in the trench where they buried the conduit. They may also be using the rebar that is embedded in the footings for this purpose. If that's the case, then you may be out of luck. I'm in agreement that it's best to make friends with the electricians to find out what they are doing.

Around here, when Bell prewired houses, they always left both ends of the prewire loop hanging outside along with a #10 ground wire that was connected inside to the service entrance ground. Of course, that was years ago since they no longer do any form of inside wiring.

In our area if no grounding is available on site, such as no electric service or too far away, the Telco pounds its own ground rod.

Jeff:

That's true everywhere, but it's a code (NEC) violation to do this if there is any form of electric or metallic water service feeding the premises. It doesn't matter if it is too far away. All grounding electrodes (rods) must be bonded together with no exceptions.

People tend to think that a ground is a ground is a ground. Nothing could be further from the truth, in fact multiple grounding electrodes that are NOT bonded together cause more problems than no grounding at all.

That's a big part of the reason that you don't see to many new buildings constructed where all metallic utilities don't enter the building in the same general vicinity.

Of course, if the building does not have an electrical service then things are different. In that case, what you described is perfectly acceptable since it is the only grounding means.

Thanks for all the replies. I think I am doing things correctly......or pretty darn close anyways. I just wanted to get some feedback from others as to how they are doing it in these situations. Also, if I am understanding this right, there is no limit on the number of feet you can run a ground wire in a premise to get a proper bond? If a wire has to be run all the way across a building.......that is acceptable, as long as it is a #6 wire? Thanks again!

Well, that's not exactly true. If the ground wire is run buried outside the limit is 40 feet then you have to drive a ground rod and continue. As a practical matter that's not going to happen inside the premises and you don't want outside influences like lightning running through the building. That's why it is required that all services enter the building together (or as close as possible) at the same location to keep the ground bond as short as possible. So you have a responsibility to put your NI at a location that will minimize the length of the grounding conductor. That requirement is the overriding factor that dictates the location of the NI, not how easily you can trench or how the inside wiring is run. That's why I talked about requiring a separate conduit under the slab for telephone and CATV. That would be the proper way.

I have the feeling that the sparkie dictates where you locate you NI due to where he decides to dump his wiring out the side of the house?

-Hal

You are correct. Typically the electricians are determining where our NID is going, as they determine where the inside wiring comes out, and if we are lucky, a ground wire as well.

I'd like to step back and welcome you to the forum, ffej010. It's nice for us to have participation from members who work on the telco side of this industry. I think we can all benefit by being able to share in how things work from opposite sides of the fence. Please feel free to chat with us often, as none of us can ever gain too much knowledge and experience.

Yep, what Ed said. To a fellow Cornhusker.

and if we are lucky, a ground wire as well

Well, if he provides a ground wire for you (and it actually gets back to ground) then I would say it's not your problem anymore. Any code problems are his.

And yeah, welcome!

-Hal

Code problems, definitely. They will be the sparkie's responsibility for sure.

The problem here is that as a regulated utility, it is this telco's responsibility to perform these installations in accordance with NEC plus RUS (formerly REA) specifications. I say this under the assumption that the independent telco involved is an RUS member, which nearly all are.

With very few exceptions, no independent telcos follow Bell specifications, so RUS is about the closest form of uniform compliance that exists.

Thanks for the kind words. I stumbled upon this site by chance, and am finding it to be very informative and helpful on a variety of topics. I usually don't like to take my work "home" with me, but I do find myself checking this site out frequently when I have spare time! Keep up the good work! And to Bill........GO BIG RED!

As the Eagles said 'you can check out but you can never leave!'
This place is the best...which is why I am on at 1:30 AM!