pedestal combination meter and main

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Re: pedestal combination meter and main

SLK and George, the NESC requires a bonding connection be made if a facility is installed within 5 ft of a power facility. Therefor, if a CATV or telephone pedestal were located within 5 ft, the would be required to be bonded. Additionally, all communications and CATV facilities are required to be bonded to the power facilities on pole lines and in trenches. Even if they serve the home from another direction, a parallel path is created for neutral currents.

I suspect the above reality is the reason that Washington state has that in their rules. In my opinion, that is they way the NEC should be written. :D
 
Re: pedestal combination meter and main

It may be more common than we think to have the phone line in the trench with the power down to the meter main pedistal or post, especially if there is more than one building on the property.

I know that we have established before that a disconnect on a post or a pedistal is a structure, but I still have a hard time thinking in those terms. Structure - "That which is built or constructed."
 
Re: pedestal combination meter and main

I just fail to see why introducing an OCPD at the meter suddenly results in parallel neutral currents flowing into the coax and phone lines. I also fail to see why a smaller parallel grounding conductor would cure it.
 
Re: pedestal combination meter and main

Originally posted by georgestolz:
I just fail to see why introducing an OCPD at the meter suddenly results in parallel neutral currents flowing into the coax and phone lines. I also fail to see why a smaller parallel grounding conductor would cure it.
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George the cable may be bonded at the pedestal then again bonded at the structure.

Adding the forth wire keeps the coax from being bonded to the neutral a second time.

At this point the coax shield becomes a parallel path for neutral current.

Draw it out. :)

Do CATV and telephone lines get bonded at the house? How?
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Through the ground wire that the phone and cable installers are required to connect to grounding system at the structure.

[ February 06, 2005, 02:11 PM: Message edited by: iwire ]
 
Re: pedestal combination meter and main

Bob
That happen's when the meter/disconnect is at the house anyway's. The phone/cable lines are still connected to both location's. I don't see a difference?
 
Re: pedestal combination meter and main

If you run a 4 wire feed from the pedestal to the house you will not bond the neutral to grounding conductor at the house.

You will connect the cable and phone grounds to the grounding system of the house but there will be no connection at the house of the cable and phone to the neutral.
 
Re: pedestal combination meter and main

I am not as familiar with the NESC as with the NEC. What section requires a bond between a CATV or Phone pedestal when it is within 5 feet of an electrical pedestal?

This rule would be news to the utilities that I deal with as they do not perform this task of cross utility bonding - that is to say no cross bonding takes place. Then again I rarely see a CATV or phone pedestal within 5 feet of an electric pedestal (I can't recall ever seeing it, but one anecdote does not a rule make), but if the pedestals were bonded, then a four wire feeder would be required. Perhaps the utilities in Colorado stay over 5 feet away by local rule in order to avoid this dilemma.

As to the statements that all phone and CATV is bonded to the poles it is mounted on, I agree. Are you suggesting that because these systems are inherently bonded somewhere in their systems to the electric grid that it is never possible to run an feeder without an equipment ground to a structure? If that is the case, there are millions of overhead three wire residential drops in Colorado alone that need to be changed...
 
Re: pedestal combination meter and main

I am not as familiar with the NESC as with the NEC. What section requires a bond between a CATV or Phone pedestal when it is within 5 feet of an electrical pedestal?

It is not required for you to be familiar with the NESC but the various utilities that we are talking about should be familiar with the NESC. Rule 350F states, "Bonding should be provided between all above ground metallic power and communications apparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by a distance of 1.8 m (6 ft) or less."

This rule would be news to the utilities that I deal with as they do not perform this task of cross utility bonding - that is to say no cross bonding takes place.

I suspect that there is no cross bonding that you know of. Do you ever open any of the enclosures or discuss this with any of the communications or power workers to see how they do their work?

Perhaps the utilities in Colorado stay over 5 feet away by local rule in order to avoid this dilemma.

That is very possible.

Are you suggesting that because these systems are inherently bonded somewhere in their systems to the electric grid that it is never possible to run an feeder without an equipment ground to a structure?

If they take a communications cable, gas pipe, metallic water pipe, etc., that is correct.

If that is the case, there are millions of overhead three wire residential drops in Colorado alone that need to be changed...

Now you are talking about service and not feeder conductors and the rules are different. :D
 
Re: pedestal combination meter and main

Originally posted by charlie:

I suspect that there is no cross bonding that you know of. Do you ever open any of the enclosures or discuss this with any of the communications or power workers to see how they do their work?
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Guilty as charged! (I mean, I don't.) :)

Where you from, SLK?
 
Re: pedestal combination meter and main

Bob I agree that if a 4-wire feed is run to the house and grounding is kept seperate from the neutral there would be no neutral current on the cable shield ( phone conductors are some what isolated because they don't directly connect to grounding but through an arisstor)
What I was getting at is most all services are 3-wire that comes to most houses and since the cable and phones also connect to the grounding at these house which is connected to the service neutral you will have the same problem. If it is a problem. Look at trailer services you are allowed to run a 3-wire feed to the first disconect out side of the trailer then switch to 4-wire that runs into the trailer. as in 550.33 exception. which would result in the very same thing.

I agree if run to a out building then you would have the cable and phone wires that would most likly be run inside of the building where it could be a fire hazard, but when out side and the fact this is done everywhere a three wire service is brought to a house. I don't see what the differance would be between a 3-wire with a disconnect at the pedestal or a three wire with the disconect at the house as far as the phone and cable wires go?
 
Re: pedestal combination meter and main

Okay, I can see the potential for problems now, and how a four wire can eliminate that. However, not installing an OCPD isn't going to change that unhappy fact. :D

What is the purpose of bonding the TV's and phones? Assume plastic pedestal housings, and a plastic box at the house. What gets bonded? Why bother?

Edit: Hi Wayne! :D

[ February 06, 2005, 11:36 PM: Message edited by: georgestolz ]
 
Re: pedestal combination meter and main

The main purpose for the bonding is to keep the path to earth as short as possible in case of a lightning strike. It also is to keep the conductors at a earth potential to prevent a shock hazard if a primary were to energize these wires. The housings might be made of plastic but the conductors will still conduct.


Hi George
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[ February 07, 2005, 12:38 AM: Message edited by: hurk27 ]
 
Re: pedestal combination meter and main

"There is a pedestal combination meter and main at the property line. Does 250.32 (B) (2) mean I may run a 3 wire feeder to the house (panel with main) and set the grounding up as if they were service entrance conductors provided there is no metallic (parallel)connection between the pedestal and the house?"

yes. I have a similar job where the utility co is requiring the service from the pole go underground to a service-pedestal with a 200amp MCB. I then have a run to the dwelling where I will install 3 conductors in PVC-Sch40. The dwelling has a UFER ground and associated bonding to water etc and will be bonded to the system neutral in the panel. The panel will be located inside the garage and will have a main breaker. I do not see any advantage in installing an EGC from the pedestal to the dwelling as the neutral is bonded at the pedestal to a ground-rod for lightning protection and again at the house where the neutral is treated like a service connection. There is no metallic connected between the pedestal and the dwelling or anything else on the property. I see this type of installation much in the same way as when we step service voltages up )(because the dwelling is on a large parcel of property) and then step it back down at the dwelling where we establish the service voltage and grounding. As mentioned by Tom in the State of Washington you be required to run the EGC. I did an installation in Seattle where the multi-meter service was on the main house and the rental had a panel w/main and I was required to run the EGC even though I had a UFER and bonding at the rental. AS always the NEC is the MINIMUM requirement.
 
Re: pedestal combination meter and main

I'm in an older neighborhood where all the houses are fed by galvanized water lines. Since all house have bonded the neut. to the water in the house and the water lines are connected to each other via the cast iron main out front, it doesn't matter how many grounds have been ran, there are now alternate neutral paths back to the transformer. Plus, the phone and coax are grounded at the house and at the pole, this creates another path back to the transformer.

A four wire system after the main is not going to fix that. If they truly wanted to fix any problems with this, they would mandate that no grounding of the cable or phone is done at the house. Also, they should put the main OC at the pole and bond there, instead. Then run a four wire to each house. If not, they're just ****ing in the wind.

[ February 07, 2005, 09:47 PM: Message edited by: charlie ]
 
Re: pedestal combination meter and main

Yes, I have opened a large number of pedestals, and no I haven't seen any of the bonds that you are talking about. I am only one guy, I have only been doing this for 15 years, and I don't claim to have seen every installation. I still don't think the bonding takes place here in Colorado between residential power pedestals and phone or coax pedestals.

Thanks for pointing out the code section in the NESC, I have been poking around in it for some time in order to increase my own knowledge. This is a curiosity thing as I agree with you that I don't need the knowledge. I still seek it, however.

My statement earlier -

If that is the case, there are millions of overhead three wire residential drops in Colorado alone that need to be changed...

did not mention services, although I probably overstated the millions section (likely more in the hundreds of thousands). I also did not add the term underground to go with overhead in my haste. Let me restate it...

If that is the case, there are hundreds of thousands of residential overhead feeders (drops if you will) and underground feeders (laterals if you will) that only have three conductors in them. All of these would need to be changed in order to meet your interpretaion of the feeder requirement as I agree that all phone and coax systems are bonded to the electric utility at some point in their system.

In short, my disagreement is not in the above aspects of this discussion. It is that a four wire feeder is not required by the NEC in the original scenario.

250.32(B)(2) clearly states...

"there are no continuous metallic paths bonded to the grounding system in both building or structures involved..."

This to me means that the continuous metal paths would need to be directly between the power pedestal at the edge of the property and the home that it feeds. The continuous metal paths that you are referring to may take place at the phone site that may be a mile away. I think the installation as I have described is safe, and within the intentions and wording of the NEC. This is why it is included as an option in the code.

For clarification -

If the power pedestal and the phone/coax pedestal are in fact bonded directly to each other, than a four wire feeder would be required. This was a good point to make, as I have never seen it, the way I do things in Colorado may not work for people in different parts of the country. The part about never using a three wire feeder I still have to respectfully disagree with.

Enjoy your day!

ps - George - I live in Fort Collins but have contracted in areas ranging to Red Feather, Castle Rock, Evergreen, Springfield, Lamar and every city on the front range between here and Castle Rock. I am well travelled, but don't know it all yet (likely never will, but won't stop trying). ;)
 
Re: pedestal combination meter and main

Originally posted by georgestolz:
What is the purpose of bonding the TV's and phones? Assume plastic pedestal housings, and a plastic box at the house. What gets bonded? Why bother?
Click to expand...
 
Re: pedestal combination meter and main

Originally posted by georgestolz:
What is the purpose of bonding the TV's and phones? Assume plastic pedestal housings, and a plastic box at the house. What gets bonded? Why bother?
Click to expand...
The shield of the coax is bonded by a grounding block at the point of entrance to the dwelling, the phone will have a grounding connection in the D-Mark that will have a lightning arrestor in it so the parrallel paths don't realy cause a problem with phone lines any more (at one time they use to ground the unused pair) But some of the newer DB phone lines do have a shield that is bonded. Most of the ones I have seen running to a house is just a DB orange cat 5. No shield.

I agree that maybe because of the phone and cable wires it would be required to run 4 wires to the building.

I just don't see this requirment as any safer than when we have the service at the building? you will still have the same wires in parallel with the neutral. that you would have if only 3 conductors was ran from the pedestal to the house. Which the previous would be the majority of most installations.

If a 4-wire instalation is that much safer then why is it not required all the way from the transformer. This would eliminate any neutral current from being on the coax, or grounding?

Maybe I'm missing somthing?

Ok charlie let me have it.
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Re: pedestal combination meter and main

I don't know if the cable construction is any different but I do know that the grounding rules are different depending upon where you are located. These rules change at the point of the main service disconnecting means and overcurrent protection.

I think of everything outside of a premises wiring system like a lake and the premises wiring system as an island. In the lake, everything readily accessible is (or is supposed to be) bonded together and kept at the same potential as the lake. On the island, the grounding system is kept separate from the current carrying system because of the close interaction with people. A separate structure is a different island unless it has a causeway (parallel metallic path) from the first structure.

Now, it is up to you whether or not you wish to defy the two Codes and do things your own way or to follow the Code that applies to you. Because of the possibility of lawsuits, my company chooses to follow the NESC. When we have work done in our office buildings (or any others that fall under the NEC), we have licensed electrical contractors do the work to the NEC rules. I don't know of anybody that is perfect but we attempt to follow the applicable Code. :D
 
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