Need for Ground Conductor Meter Socket to Main Panel

[ccarr7]

Hi Guys,

I have a resident who is installing a new meter socket for a single phase 100A service. There is approx. 10' of distance between the meter socket and the main distribution panel (opposite side of the house), so per City Code I had him install a 100A breaker in the meter socket. I also had him land his ground electrode conductors from the water pipe and a ground rod in the meter socket, and had him bond the neutral to ground there, as well. We inspected the service today and found that there is no ground conductor pulled from the meter socket to the main panel. The two phase conductors and neutral between the two are installed in a rigid steel pipe, so I figure that the electrician is relying on the conduit as the path to ground from the panel to the meter socket. FYI - the main panel includes a 100A main breaker.

What do you guys think of this? I know that the conduit is an acceptable means for equipment grounding, so I think that this is OK. But, I want to get other opinions.

Thanks,
Creig

 

[DavisIMI]

I would install a egc. The home owner probably didn't install a bonding jumper to the ridgid conduit and a grounding bushing did he? This would have to be done on both ends for the conduit to be a legal ground.

 

[augie47]

Locally, if that 10' between the meter socket and the panel is inside the house it would never be accepted without an outside disconnect. That said, it may be acceptable in your jurisdiction.
If the conductors run straight from the meter to the panel, then he should not pull an grounding conductor. The service panel would need a neutral (grounded) bond per 250.24. An additional conductor is likely to violate 300.3(B)(1).
In regard to the metallic conduit he needs to meet 250.92 which might require a bonding bushing or locknut on one end.

 

[infinity]

Since the main is at the meter enclosure you would need 4 conductors between the meter enclosure and the panel which is what you have. The metallic raceway is permitted as the EGC. No additional bonding is required since you're on the load side of the service disconnect.

 

[roger]

Hi Guys,

so per City Code I had him install a 100A breaker in the meter socket.

With this being the case, an EGC is needed from the Meter socket to all downstream equipment and the RMC would cover this requirement assuming the proper terminations are used.

Roger

 

[augie47]

sorry Roger, I haven't learned to read yet. I missed the "outside main"
Thanks for covering.

 

[jcole]

If the meter has main disconnect and the main bonding jumper in it, the conductors after the main would be a feeder not service entrance conductors. Therefore, I would think this is a legal install.



Looks like somebody beat me to it. Sorry.

 

[roger]

sorry Roger, I haven't learned to read yet. I missed the "outside main"
Thanks for covering.

Gus, don't feel alone, I do the same thing.

Roger

 

[DavisIMI]

If the meter has main disconnect and the main bonding jumper in it, the conductors after the main would be a feeder not service entrance conductors. Therefore, I would think this is a legal install.

If ridgid conduit is properly bonded.:wink:
Remember he said a home owner had done this install.

 

[LarryFine]

Also, the neutral system must be isolated from the enclosure and EGC system in the panel.

 

[infinity]

[If the meter has main disconnect and the main bonding jumper in it, the conductors after the main would be a feeder not service entrance conductors. Therefore, I would think this is a legal install.
/QUOTE]

If rigid conduit is properly bonded.:wink:
Remember he said a home owner had done this install.

Why wouldn't it be properly bonded? The installer didn't tighten the locknuts?

 

[DavisIMI]

Why wouldn't it be properly bonded? The installer didn't tighten the locknuts?

250.92,B,(4)Other listed devices, such as bonding-type locknuts, bushings, or bushings with bonding jumpers. Bonding jumpers meeting the other requirements of this article shall be used around concentric or eccentric knockouts that are punched or otherwised formed so as to impair the electricl connection to ground. Standard locknuts or bushings shall not be the sole means for the bonding required by this section.

 

[jcole]

[Why wouldn't it be properly bonded? The installer didn't tighten the locknuts? /QUOTE]

250.92,B,(4)Other listed devices, such as bonding-type locknuts, bushings, or bushings with bonding jumpers. Bonding jumpers meeting the other requirements of this article shall be used aroundconcentric or eccentric knockouts[that are punched or otherwised formed so as to impair the electricl connection to ground.Standard locknuts or bushings shall not be the sole means for the bonding required by this section.

This has to do with services. The service ends at the first disconnect. Wouldnt be a bad idea though. But not required because this is considered a feeder not service. Agree?

 

[DavisIMI]

1. First of all, our jobs, as electricains, is to install a safe installation. To do that we are provided the NEC code book which is the minimumrequirements. It is our job to know and interpret these requirements and provide the safest installation possible.
2. The reason for grounding and bonding,( which I'm sure you know), is to provide an " Effective Ground-Fault Current Path", which defined by our NEC is,"Effective Ground-Fault Current Path. An intentionally constructed, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors on high-impedance grounded systems."

Now I for one go above and beond the minimum requirements when it comes to protecting persons and property, ( not to mention my contractor lisc.), so I always pull a egc and bond the conduit in the legal required means.

If you have the 2008 NEC code book, please look up the definition: Bonded (Bonding).

Bonding Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.
Both concentric- and eccentric-type knockouts can impair the electrical conductivity between metal parts and may actually introduce unnecessary impedance into the grounding path. Installing bonding jumper(s) is one method often used between metal raceways and metal parts to ensure electrical conductivity. Bonding jumpers may be found at service equipment [250.92(B)], bonding for over 250 volts (250.97), and expansion fittings in metal raceways (250.98). Exhibit 100.3 shows the difference between concentric- and eccentric-type knockouts. Exhibit 100.3 also illustrates one method of applying bonding jumpers at these types of knockouts.

Exhibit 100.3 Bonding jumpers installed around concentric or eccentric knockouts. ( I tried to paste the picture in 2008 NEC, oh well.)

And please look up 250.12.
250.12 Clean Surfaces.
Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded shall be removed from threads and other contact surfaces to ensure good electrical continuity or be connected by means of fittings designed so as to make such removal unnecessary.

Now, if one chooses not to pull a egc one is required to install raceway, by minimum requirements, by code. That means they have to scrape, grind, file the paint off of the panel where the conduit is connected, on both sides of conduit, for the conduit to become a legal egc.

Now from the defininition of Bonded( Bonding) from above and the picture and commentary which follows. When one is installing a meter base, load center, panel board, whatever, and these enclosers have concentric or eccentric knockout, unless you have a conduit large enough that you have to remove all knockouts in that on hole or you knockout your own hole with knockout punch or holesaw, just applying locknuts will not get it.

Now being that this thread is about a 100amp service, and a home owner doing the installation, I dont believe that:
1. The owner used a 2" or larger conduit, for one, the price, which would mean they didnt use the last knockout in the hole which conduit is installed.
2. The owner took the time or trouble to scrape or file the paint away on both the meter base and the load center. Because for one, most electricains I have seen wont take the time or trouble either.

Now, you can argue this all you want but in trying to save the money by not pulling a egc you create more work and have to buy more materails to make it a legal installation.
Ya,ya, I know it's a feeder and not a service so its legal blah,blah,blah. It's not if the installation is not installed in the corect way. I can not believe people will argue about something like this, all your trying to do is get buy the quickest cheapest way possible way. This is the only way it will fly in this neck of the woods, and if not in yours, the city needs to be looking for a new inspector.

 

[DavisIMI]

One more point if I may.
The author of this thread stated that the required neutral to ground bond was done at the meter base, which is perfectly leagal, and that no egc was pulled to the load center. This being said the only ground fault path to clear and ground faults is this conduit, which is also legal, my point is if this person didn't follow any of the requirement above I would dare say this is not a reliable or effective ground fault path. Unless the paint has been removed at locknuts or grounding bushing and bonding jumpers are applied. This is my point, yes at first look the system would seem to be legal but I dare say a closer look would reveal that it is not and a fire and saftey hazzard. Thats why I always install the correct size egc regardless of code requirement and always remove paint at conduit terminations, with locknuts or hubs, that way I know there is a effective low impeadance ground fault path. And at my company its my way or the highway.:wink:

 

[roger]

1. First of all, our jobs, as electricains, is to install a safe installation. To do that we are provided the NEC code book which is the minimumrequirements.['quote] And the NEC minimum is well above "bottom of the barrel" safe.

If a company had a policy that the minimum vehicle you could drive would be a Cadillac, it would still be the mininmum but well above the lowest level safe vehicle. The word "minimum" is not anything to be ashamed of.

It is our job to know and interpret these requirements and provide the safest installation possible.

And using the scenario above, a Kia would be suffucient even though we would have to stay with the minimum being the Cadillac

2. The reason for grounding and bonding,( which I'm sure you know), is to provide an " Effective Ground-Fault Current Path", which defined by our NEC is,"Effective Ground-Fault Current Path.

Grounding would not be a part of a low impedance Effective Ground-Fault Current Path.

Now I for one go above and beond the minimum requirements when it comes to protecting persons and property, ( not to mention my contractor lisc.), so I always pull a egc and bond the conduit in the legal required means.

That is your perogative but, a metallic raceway would most likely be a better fault clearing path than a conductor

If you have the 2008 NEC code book, please look up the definition: Bonded (Bonding).

Bonding Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.
Both concentric- and eccentric-type knockouts can impair the electrical conductivity between metal parts and may actually introduce unnecessary impedance into the grounding path. Installing bonding jumper(s) is one method often used between metal raceways and metal parts to ensure electrical conductivity. Bonding jumpers may be found at service equipment [250.92(B)], bonding for over 250 volts (250.97), and expansion fittings in metal raceways (250.98). Exhibit 100.3 shows the difference between concentric- and eccentric-type knockouts. Exhibit 100.3 also illustrates one method of applying bonding jumpers at these types of knockouts.

Exhibit 100.3 Bonding jumpers installed around concentric or eccentric knockouts. ( I tried to paste the picture in 2008 NEC, oh well.)

I think this has already been covered in one way or another.

And please look up 250.12.
250.12 Clean Surfaces.
Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded shall be removed from threads and other contact surfaces to ensure good electrical continuity or be connected by means of fittings designed so as to make such removal unnecessary.

A locknut will cut through paint and surface finishes.

Now, if one chooses not to pull a egc one is required to install raceway, by minimum requirements, by code. That means they have to scrape, grind, file the paint off of the panel where the conduit is connected, on both sides of conduit, for the conduit to become a legal egc. [

Once again, a locknut will get down to clean metal. If we are using a lug or some other fitting, I have never had a problem cleaning off paint.

Now from the defininition of Bonded( Bonding) from above and the picture and commentary which follows. When one is installing a meter base, load center, panel board, whatever, and these enclosers have concentric or eccentric knockout, unless you have a conduit large enough that you have to remove all knockouts in that on hole or you knockout your own hole with knockout punch or holesaw, just applying locknuts will not get it.

You could remove all the rings and use reducing washers (yeah, I know this is weird but it is perfectly fine and the back up can be found in the UL White Book)

Now being that this thread is about a 100amp service, and a home owner doing the installation, I dont believe that:
1. The owner used a 2" or larger conduit, for one, the price, which would mean they didnt use the last knockout in the hole which conduit is installed.
2. The owner took the time or trouble to scrape or file the paint away on both the meter base and the load center. Because for one, most electricains I have seen wont take the time or trouble either.

See the locknut comments above.

Now, you can argue this all you want but in trying to save the money by not pulling a egc you create more work and have to buy more materails to make it a legal installation.

It doesn't create more work IMO.

Ya,ya, I know it's a feeder and not a service so its legal blah,blah,blah. It's not if the installation is not installed in the corect way. I can not believe people will argue about something like this, all your trying to do is get buy the quickest cheapest way possible way. This is the only way it will fly in this neck of the woods, and if not in yours, the city needs to be looking for a new inspector.

If your inspector makes up his/her own rules and you go along with it so be it.

Roger

 

[roger]

One more point if I may.
The author of this thread stated that the required neutral to ground bond was done at the meter base, which is perfectly leagal, and that no egc was pulled to the load center. This being said the only ground fault path to clear and ground faults is this conduit, which is also legal, my point is if this person didn't follow any of the requirement above I would dare say this is not a reliable or effective ground fault path. Unless the paint has been removed at locknuts or grounding bushing and bonding jumpers are applied. This is my point, yes at first look the system would seem to be legal but I dare say a closer look would reveal that it is not and a fire and saftey hazzard. Thats why I always install the correct size egc regardless of code requirement and always remove paint at conduit terminations, with locknuts or hubs, that way I know there is a effective low impeadance ground fault path. And at my company its my way or the highway.:wink:

Down load Gemi for some information on using metallic conduit and tubing for bonding.

Roger

 

[DavisIMI]

Grounding would not be a part of a low impedance Effective Ground-Fault Current Path.

I think you should read your book, I've read more books on grounding and bonding than I care to mention, but I would suggest one to get you started on the right track, SOARES Book on Grounding and Bonding.

That is your perogative but, a metallic raceway would most likely be a better fault clearing path than a conductor

Again, I suggest you do some reading.There are alot of variables that have to be taken into account on this subject such as tightness of locknut, couplings, and flex connectors to name a few.

A locknut will cut through paint and surface finishes.

If this was true there would be no need for artical 250.12. And they sure wouldn't be telling us to remove paint from the surface of enclosers if there wasn't a need.

If a company had a policy that the minimum vehicle you could drive would be a Cadillac, it would still be the mininmum but well above the lowest level safe vehicle. The word "minimum" is not anything to be ashamed of.

,

And using the scenario above, a Kia would be suffucient even though we would have to stay with the minimum being the Cadillac

I like to think this is why I'm chosen over my competitors, I know its not over cost, you get what you pay for.

 

[don_resqcapt19]

Quote:
Grounding would not be a part of a low impedance Effective Ground-Fault Current Path.

I think you should read your book, I've read more books on grounding and bonding than I care to mention, but I would suggest one to get you started on the right track, SOARES Book on Grounding and Bonding.

If you think that grounding and the fault clearing path have anything to do with each other, then I suggest that you re-read the books that you are talking about.

 

[iwire]

If you think that grounding and the fault clearing path have anything to do with each other, then I suggest that you re-read the books that you are talking about.

I also agree with Roger and Don.