Curiousities abound

[George Stolz]

#1: Saw something today that had me scratching my head. A #6 bare was run from the phone/TV demarc into a unit of a threeplex, and was landed in a MLO panel in the closest unit. From there, another #6 ran from the panel to a water pipe qualifying as a grounding electrode per 250.52(A). However, this setup is not replacing the required GEC.

Ideas as to what it's purpose is, anyone?

#2: If three water pipes qualifying as grounding electrodes are present in a structure, they must all be used, right?

 

[petersonra]

Re: Curiousities abound

perhaps a ground for the telco lines?

I'm not sure it is to code, but my guess is that's what they are doing.

[ August 15, 2005, 11:00 PM: Message edited by: petersonra ]

 

[physis]

Re: Curiousities abound

I often don't understand what comm people have done?

 

[George Stolz]

Re: Curiousities abound

No, this was a co-worker of mine.

I was distracted by the Pam Anderson Roast on Comedy Central. If you watched it, you know why.

To better phrase my thought that I was trying unsuccessfully to convey before...

 

[physis]

Re: Curiousities abound

I'm not impressed by naked people on TV, I can see as many naked people as I want. But I think I understand now.

 

[George Stolz]

Re: Curiousities abound

Okay, so now the guy who did it is wondering why he has been made to, so I will elaborate with more details.

The building is a three-plex. Judging from what I saw, there are substantial firewalls separating units, so technically, they could be considered "seperate structures" as outlined in 230.6. There is a three-stack metermain service, fed by the utility (conductor size unknown). They are planning on running a #2 CU GEC to the water pipe in only the closest unit, which is acceptable to the AHJ.

There are separate water "services" for each unit--so under the one roof, there are three water pipes that qualify for 250.52(A)(1). (The systems are Pex beyond 3'.)

My first question is: Do all three water pipes need to be used as Grounding Electrodes by code? My answer is yes.

Since the service stops outside one unit, and has feeders supplying the three units, Article 230's opinion of a structure becomes irrelevant. We would have to fall back on 100, which would seem to be the structure as a whole.

Therefore, I think that a #2 CU GEC must be run to all three water pipes.

The second part of my typically long post, is the LV grounding issue. My boss had an interesting take on why it would be illegal. He said that somewhere in the NEC it is stated that the grounding connection for a low-voltage demarc or similar area is required to be accessible without opening a Line Voltage enclosure. So landing the #6 for the phone guys in the 120/240 panel is violating that.

I haven't looked for that code yet, I am hurrying so my wife can talk to her mom. I'm thinking the purpose is bonding, not grounding, but that's based on an assumption. Essentially, the AHJ has required a full size GEC to the closest water pipe, and then the farther water pipes are connected to their panel in each unit by a #6.

What makes it weird, is that the plumbing in all these structures is Pex.

So, thoughts?

[ August 17, 2005, 09:56 PM: Message edited by: georgestolz ]

 

[hbiss]

Re: Curiousities abound

I agree with the inspector. The services are connected to the nearest GE and that is all that is required other than two ground rods. Since the plumbing within the units is plastic I don't even see a reason to bond the water lines in the other two units but it is a good idea.

As for a EGC originating within a panel for TELCO and CATV bonding I see no problem with that either and in fact it is encouraged that the EC leave a tail or ground bar for that purpose.

I believe your boss was thinking about GEC's or EGC's originating in a meter pan.

-Hal

 

[George Stolz]

Re: Curiousities abound

Okay, here's a thought.
In this picture, it is installed as described above:

The transformer is the red box to the right, feeding the service, which has a GEC connected to the closest water pipe. The other water pipes are connected to the panels.

If the tranformer has a primary to secondary failure, it will send high voltage into the structure. This voltage is supposed to travel along the GEC, to the grounding electrode, attempting to return to it's source, the substation via earth.

With the other #6 conductors in place, the current would travel to the panels, and attempt to use the #6 to those grounding electrodes.

The #2 is sized correctly for the fault conditions imposed. The #6 is too small.

Is my reasoning correct?

 

[iwire]

Re: Curiousities abound

George you told me this was long you did not say it was going to be difficult as well.

I have to say I have not been involved with a project like you describe.

What catches my attention first is this.

The building is a three-plex. Judging from what I saw, there are substantial firewalls separating units, so technically, they could be considered "seperate structures" as outlined in 230.6.

IMO before any definite answer to the question can be given we have to know if it is considered separate structures or not.

I believe this decision must be made in the design process and not on the job simply by seeing firewalls.

 

[George Stolz]

Re: Curiousities abound

Originally posted by iwire:
George you told me this was long you did not say it was going to be difficult as well.

I have to say I have not been involved with a project like you describe.

Okay, but from looking at 250.50 & .52, doesn't it seem that all the grounding electrodes must be used, not just one of every type available?

What catches my attention first is this.

The building is a three-plex. Judging from what I saw, there are substantial firewalls separating units, so technically, they could be considered "seperate structures" as outlined in 230.6.

IMO before any definite answer to the question can be given we have to know if it is considered separate structures or not.

As far as the NEC is concerned, it would be one structure, wouldn't it? Remember, I have three disconnects outside, in one location. I then have main feeders supplying the units. Therefore, 230's opinion flies out the window, doesn't it? The service stopped outside, it never applied indoors at all.

It just seems excessive to require all three electrodes to be used.

But it doesn't seem as though 250.50 is requiring one of each, it is requiring all of each.

 

[George Stolz]

Re: Curiousities abound

Okay, fifteen guys chime in for RATM, somebody can take a second for this bump.

 

[al hildenbrand]

Re: Curiousities abound

Hey George,

There's a lot here. I'd suggest teasing it apart, a bit at a time.

Let me start by taking your 2nd question:

My boss had an interesting take on why it would be illegal. He said that somewhere in the NEC it is stated that the grounding connection for a low-voltage demarc or similar area is required to be accessible without opening a Line Voltage enclosure. So landing the #6 for the phone guys in the 120/240 panel is violating that.

I start by thinking about the #6 running from the MLO panels to the "low-voltage demarc or similar area." Looking at 250.94, and specifically 250.94(3) and 250.94(3)FPN No. 1, the #6 that is accessible outside of the Line Voltage enclosure is all that is needed for a "legal" connect by the low voltage guys.

 

[George Stolz]

Re: Curiousities abound

Originally posted by al hildenbrand:
...the #6 that is accessible outside of the Line Voltage enclosure is all that is needed for a "legal" connect by the low voltage guys.

Okay, so what we have is a violation of 800.40(B)(3). That makes sense. All he has to do is run that #6 back to a water pipe, and he's in business.

So, what about the 3 water pipes? Must they all be used as grounding electrodes? Or is one of each type acceptable?

 

[al hildenbrand]

Re: Curiousities abound

Posted by George Stolz
what we have is a violation of 800.40(B)(3)

(2002 NEC 800.40(B)(1)(3))

Ah, so. There is also a job description divergence in this "coworker". I hadn't assumed that. I was imagining you and the coworker worked for the same employer.

This sounds more like exceeding the limits of one's license. And with that, getting out of one's depth. I'll just bet someone was trying to be "helpful" and thought they were correcting the oversight of the electrician.

I'd say that all the #6s the lovo worker installed at the MLO panel are violations of 2002 NEC 800.40(B)(1)(3) because the lovo worker connected them inside the MLO panel.

As you say, George, had they just gone straight to the water pipe GE, everything would have been compliant.

Now, for the next part of your question. As for the two #6 MLO panel EGC to water pipe GE bonds. . .am I correct in assuming that this is a municipal water service coming from one water main to the structure in metal pipe? And if you don't know specifically, is it reasonable to assume that the electrical AHJ does know?

I think we could bandy about the language of 250.50 & .52, but to my thinking, electrically, a single metal water main entering a single structure at three points is still a single GE.

 

[George Stolz]

Re: Curiousities abound

Originally posted by al hildenbrand:
I hadn't assumed that. I was imagining you and the coworker worked for the same employer.

This sounds more like exceeding the limits of one's license. And with that, getting out of one's depth. I'll just bet someone was trying to be "helpful" and thought they were correcting the oversight of the electrician.

Somehow, this fellow (with my company) got roped into doing the job of the LoVo guy. Generally, the find their own ground, but in this case, the Low Voltage is located remotely from the service, and the ground rod's GEC per the routine.

I'd say that all the #6s the lovo worker installed at the MLO panel are violations of 2002 NEC 800.40(B)(1)(3) because the lovo worker connected them inside the MLO panel.

A licensed journeyman made the connection per the somebody's request.

The violation comes into play in ten years, when the LoVo employee needs access to his grounding connections. That individual would have to open the panel.

As you say, George, had they just gone straight to the water pipe GE, everything would have been compliant.

That would be my recommendation. He'll probably read this before I get a chance to tell him. He's a lurker.

Now, for the next part of your question. As for the two #6 MLO panel EGC to water pipe GE bonds. . .am I correct in assuming that this is a municipal water service coming from one water main to the structure in metal pipe? And if you don't know specifically, is it reasonable to assume that the electrical AHJ does know?

When I asked the AHJ (he's watching this too ), he said he wouldn't have required the bond if he knew the system was Pex. In this jurisdiction, with multifamily and large structures, it's common to get the service up, the GES in, the panels in, and a temp GFI below the panel, and energize the system prior to actually roping the units. It eases the burden on the trades, having to lug 400+' of cord around every day.

I think we could bandy about the language of 250.50 & .52, but to my thinking, electrically, a single metal water main entering a single structure at three points is still a single GE.

Perhaps the language should be amended to reflect this. It's a very reasonable view, but the NEC seems to be shortsighted on this issue. It can only see out ten feet.

[ August 26, 2005, 08:13 PM: Message edited by: georgestolz ]

 

[al hildenbrand]

Re: Curiousities abound

Hey George,

The violation comes into play in ten years, when the LoVo employee needs access to his grounding connections.

Since a licensed electrician installed the #6, isn't it then part of the grounding electrode system and the connection at the low voltage equipment is the only connection that the LoVo worker needs to access.

I mean, if I tail out a exposed 6" piece of #6 from the panel and leave it for connection of ground leads that the communication systems need, what's the difference between a split bolt connecting the #6 to a #12 (or whatever) that in turn connects to the ground terminal on the lovo primary protector, or a long enough #6 landing directly on the primary protector. Seems to me, the only connection the LoVo worker will have to manipulate is that to the primary protector. . .even if 2002 NEC 800.40(B)(1)(3) didn't exist, why would the LoVo worker do anything with the end of the #6 inside the panel?

 

[al hildenbrand]

Re: Curiousities abound

When I asked the AHJ (he's watching this too ), he said he wouldn't have required the bond if he knew the system was Pex.

Am I understanding you to say that the #2 GEC from the Meter/Service Disco is connected to a plastic water main? . . .And from that, I also infer that the two #6s are also connected to plastic water mains?

 

[George Stolz]

Re: Curiousities abound

Al wrote:
Since a licensed electrician installed the #6, isn't it then part of the grounding electrode system and the connection at the low voltage equipment is the only connection that the LoVo worker needs to access.

I like the way you think.

Am I understanding you to say that the #2 GEC from the Meter/Service Disco is connected to a plastic water main?

Metallic underground water pipe, into view in the basement for 3', then Pex afterward.

We're nuts, but we're not crazy. Plastic lines get PVC bonding, not copper.

 

[iwire]

Re: Curiousities abound

George as I said before IMO it is absolutely essential to know if the building dept. has determined these connected buildings are separate structures or not.

IMO IF the building department has determined these buildings are separate structures then 250.32 kicks in.

250.32 Two or More Buildings or Structures Supplied from a Common Service.
(A) Grounding Electrode. Where two or more buildings or structures are supplied from a common ac service by a feeder(s) or branch circuit(s), the grounding electrode(s) required in Part III of this article at each building or structure shall be connected in the manner specified in 250.32(B) or (C). Where there are no existing grounding electrodes, the grounding electrode(s) required in Part III of this article shall be installed.

If they are not determined to be separate structures than the 'normal' rule of 250.50 is the section of importance.

250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.

IMO the words "If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6)" do not mean one of each item. IMO those words mean all the items if available.

So I would say you would have to hit each of the 3 water services with a GEC.

Yes I understand that electrically they are all the same, but I do not see that addressed in the NEC. I think it is written on the side of caution so we do not have to concern ourselves with what happens outside underground.

Read the list of electrodes [250.52(A)(1) through (A)(6)] that we are required to use if available no where does it say once you use 3 or 4 of these you can forget the rest.

What I am saying is it is my opinion that ALL the available electrodes must be used, redundant or not.

Bob

 

[George Stolz]

Re: Curiousities abound

Originally posted by iwire:
George as I said before IMO it is absolutely essential to know if the building dept. has determined these connected buildings are separate structures or not.

IMO IF the building department has determined these buildings are separate structures then 250.32 kicks in.

So, let's take that for a stroll. Let's say that they are considered "seperate structures." (In truth, I believe at least one of the buildings in question is.)

How do we apply 250.32? I would think, since I'm running SER, and thus am running an EGC from the "other structure, then I simply don't bond the neutrals and grounds together, and run a (#6) GEC sized for the ungrounded conductors entering the structure (#2 AL), and then am complete. Applying 250.32 to this is fairly straightforward, on the tenant's end.

Applying 225 would be a might bit trickier. Now I would need a disconnect on the outside of this structure. The one attached to the other unit, at the service, isn't in compliance with 225.32.

But leaving the other bit out of this for now, the installation I described (1 large GEC from the service to nearest water, then smaller GEC's from each other unit's panel to water) is pretty much along the lines of 250.32, I guess.

If they are not determined to be separate structures than the 'normal' rule of 250.50 is the section of importance.
...

Read the list of electrodes [250.52(A)(1) through (A)(6)] that we are required to use if available no where does it say once you use 3 or 4 of these you can forget the rest.

What I am saying is it is my opinion that ALL the available electrodes must be used, redundant or not.

See, that's what I thought. It sure is interesting to see how much calling something a "seperate structure" can affect the grounding picture!