(3) temporary poles, (1) service - do they each need a ground rod?

[tryinghard]

...The statement "all electrodes shall be bonded together between structures" sounds like a dedicated bonding jumper would be installed to accomplish that...

In my understanding this is correct, it is exactly why 250-32(B)(1) and 250-50 exist in directing us so; 250-32(B)(2) just uses the grounded [neutral] conductor as a duel purpose.
If these were services rather than feeders they would be as you say incidentally bonded, but Lee?s case is distributing feeders to structures so he has to apply 250-32(B)(1) or (B)(2) (4w or 3w 1ph circuit respectively)

 

[George Stolz]

I disagree, I think you're reading too much into it - but that's just my opinion.

Edit to add: If your view is correct, then 250.32 is explicitly permitting a 250.6 violation when the neutral is used as the "inter-structure bonding jumper."

 

[RUWired]

...unless you wrapped 20' of #4 around the bottom of the pole...(a ground ring).
Don

Your slipping Don,Ground rings are a minimum #2

.

 

[iwire]

Here it's a ground rod at the main panel, they pull quadplex to the "subpanels" and we treat them as such.

So the department has chosen to ignore the NEC?

How about they make an amendment so everyone is on the same page?

 

[don_resqcapt19]

Bob,

Your slipping Don,Ground rings are a minimum #2

Ok, but is my 20' of #2 wrapped around the 4 x4 or 6 x 6 a ground ring?
Don

 

[iwire]

is my 20' of #2 wrapped around the 4 x4 or 6 x 6 a ground ring?

Sure, as long as we call the post a structure.

 

[tryinghard]

I disagree, I think you're reading too much into it - but that's just my opinion.

Edit to add: If your view is correct, then 250.32 is explicitly permitting a 250.6 violation when the neutral is used as the "inter-structure bonding jumper."

George maybe I am but here?s my logic with Lee?s application.
He needs 120/240v 1ph circuitry brought to 3 different temp. power poles. At minimum a 3w circuit is required to function A, B, & N, but there are a few questions that must be answered to determine his application.

Q1: Are these services or feeders?
A: Outside feeders (225 II specifically applies)

Q2: Is there more than one building or structure involved?
A: Yes 3 temp. power poles (250-32 specifically applies including the definition of structure)

Q3: Is an electrode required at each pole?
A: Yes (250-32 specifically applies)

The quantity of conductors needs to be determined as well, 3 are for sure - A, B, & N - meaning the real issue is an equipment grounding conductor [EGC] needed or not? If it is needed its function will be to provide the ?Effective Ground-Fault Current Path? as described in 250-4(5), and if it is not needed the neutral will provide this as a duel function also returning current. In this light a few more questions must be answered.

Q4: Is the 4th conductor [EGC] required?
A.1: NO, if these are services the grounded conductor [neutral] provides this as per 250-24, 250-28 & 250-142(A) that includes the qualification of 250-32(B) (if Lee meets this qualification he will be allowed to use a 3w feeder [not service]!

A.2: YES, because these are in fact load-side feeders rather than services and the rule is explained in a few places like 250-25(5) (that includes FPN to see 250-32) & 250-142(B) (that specifically links it?s reasoning to 250-32(B), (BUT again if Lee meets this qualification in 32(B)(2) he will be allowed to use a 3w feeder. George I don?t know if you realize this but this is what you agreed to in your post #18)

In summary these circuits can function safely as 3 or 4 wire only as determined by the criteria of 250-32 (B) and these are multiple structures which is only addressed in 250-32. It is the NEC that places all the emphasis for this type of application on 250-32 not me. My opinion of 250-32 has always been to use 250-32(B)(1) primarily and (B)(2) rarely in order to eliminate current on EGC?s as well as objectionable current, meaning if in doubt install an EGC and do not bond the neutral. In fact I?d like to see EGC?s from the utility service transformers and they can bond!

Lee can actually qualify as a 3 or 4 wire circuit I don?t know where else to qualify this other than 250-32. He has a unique situation in that he has lost a phase conductor and wants to use a 3 wire circuit but only Lee can determine this through the criteria of 250-32(B)(2).

So my view/opinion of 250-32 is NOT explicitly permitting objectionable current but it is extremely integral to qualify the need of an equipment grounding conductor as opposed to using the neutral in a duel purpose (3 or 4 wire circuit in Lee?s case)

 

[cowboyjwc]

So the department has chosen to ignore the NEC?

How about they make an amendment so everyone is on the same page?

No. We just don't consider a temp pole a structrue. We also don't consider a light pole a structure.

 

[George Stolz]

Sorry for the slow reply.

I really don't have a response for most of what you wrote - we both agree that 250.32 applies. However, I will pick a bone on one item:

My opinion of 250-32 has always been to use 250-32(B)(1) primarily and (B)(2) rarely in order to eliminate current on EGC?s as well as objectionable current, meaning if in doubt install an EGC and do not bond the neutral.

From an enforcment perspective, this has no merit, IMO. (B)(1) and (B)(2) stand on level ground in the 2005, there is no reason for a red tag if the conditions of (B)(2) are met.

There is no reason to expect objectionable current on an EGC unless one has been installed and incorrectly rebonded beyond the main bonding jumper at the premises service. I don't understand how you come around to the notion that not including an EGC is going to result in objectionable current on an EGC that doesn't exist? :-?

 

[George Stolz]

No. We just don't consider a temp pole a structrue. We also don't consider a light pole a structure.

John, can you explain 225.32 exception 3 and 4, if a pole is not a structure? Why would we need an exception for a non-applicable item?

 

[tryinghard]

There is no reason to expect objectionable current on an EGC unless one has been installed and incorrectly rebonded beyond the main bonding jumper at the premises service. I don't understand how you come around to the notion that not including an EGC is going to result in objectionable current on an EGC that doesn't exist? :-?

If a parallel path exists between the neutral conductor and metallic grounded items objectionable current WILL flow through the bond and onto the metallic grounded items including any branch equipment grounding conductors that have ground continuity at their destination. So if 250-32(B)(2)&(2) is violated it will create a neutral parallel path!

We are still dealing with wiring from the old days (as well as dumb installations) that intentionally bond the neutral to case past the service disconnect. So they don?t have an EGC with the feeder, then when other branch circuitry is installed that does have an EGC it will likely have objectionable current flowing on it because of the incorrect bond past the service disconnect. This is why the rule is no bonding past the service disconnect as per 250-24(A)(5) & 250-142(B) except for separately derived systems and 250-32(B)(2)

 

[George Stolz]

If a parallel path exists between the neutral conductor and metallic grounded items objectionable current WILL flow through the bond and onto the metallic grounded items including any branch equipment grounding conductors that have ground continuity at their destination.

About the only way this could come about is if there is a grounding electrode in common between the two structures, and of the electrodes available the only likely electrode is a metallic water pipe.

In the case of detached garages there is a small chance that a metallic line will be run out at some future time and connected to the electrical system at the garage. With the popularity of plastic piping, and the possibility that an unqualified installer will not think to connect it to their electrical system, I believe the chances are pretty low in those applications of this section being abused.

In the instance of temp poles and pole lights, I can't envision any likely scenario that would lead to an unqualfied installer generating a violation of 250.32(B)(2) after the qualified and compliant original installation, IMO.

 

[tryinghard]

It could probably be any mixture of electrodes and phone or coaxial lines between the structures constitute a metallic path, these will be in parallel to the neutral if they ground at each end.

Fact is stray and objectionable current exists on most sites (old and new). Some are induced but most of the time it?s from mis-wiring. Even the secondary service often includes a parallel path with electrodes at the transformer as well as the service disconnect, once this path is in the rest of the circuitry is susceptible.

These reasons are why 250-32(B)(2) exists ? coupled with 250-24(A)(5) & 250-142(B) ? if it is adhered to it?s not a problem, and that means every technician, lineman, plumber, general contractors workers?apply correctly

 

[cowboyjwc]

John, can you explain 225.32 exception 3 and 4, if a pole is not a structure? Why would we need an exception for a non-applicable item?

Some of them are saying that we need a grounding rod at each temporary pole because it is a structure and so they are saying that 250.32 applies and I say that it doesn't. I say it's not a structure and therefore does not need to have a ground rod (other than the main pole) and can simply be treated as a subpanel. 225.32 is talking about disconnecting means our discussion is about grounding.

 

[George Stolz]

It could probably be any mixture of electrodes and phone or coaxial lines between the structures constitute a metallic path, these will be in parallel to the neutral if they ground at each end.

How often is there something left to bond on phones and coax after the utility termination?

Even the secondary service often includes a parallel path with electrodes at the transformer as well as the service disconnect, once this path is in the rest of the circuitry is susceptible.

I have no idea what you're saying, can you draw me a picture?

225.32 is talking about disconnecting means our discussion is about grounding.

225.32 is using an Article 100-defined word. A word defined in 100 is universal throughout the NEC.

If a pole is a structure when we're discussing a disconnecting means, then it is also a structure when we're discussing grounding, because "structure" is a universal word in the NEC, IMO.

 

[tryinghard]

How often is there something left to bond on phones and coax after the utility termination?

Most often with two or more building situations, these ?daisy chain? between buildings that are grounded

I have no idea what you're saying, can you draw me a picture?

I haven?t figured out how to upload a picture yet but I?ll try to re-explain.

Utility transformer has and electrode, service disconnect has another electrode. Both of these electrodes bond the to grounded [neutral] conductor at each end causing a parallel path for returning current. So every time current returns on the neutral it will also simultaneously return through the electrodes, if you add other metallic items that also bond at each end they will also have neutral current (phone/coaxial/conduit?). At the same time current will flow through every EGC terminated at the service disconnects common bus that has any continuity to ground at its destination, these branches do not have to be ahead of the service disconnect to be affected. Once a parallel path is established returning current will flow on every path available to it?s source the XO of the serving XFMR

 

[tryinghard]

This picture [if it shows up] is an example of a violation of 250-32(B)(2). If the metal raceway does not exist ANY metallic items between the structures or buildings will cause a parallel path enabling objectionable current to flow multiple routes.

 

[tryinghard]

Some of them are saying that we need a grounding rod at each temporary pole because it is a structure and so they are saying that 250.32 applies and I say that it doesn't. I say it's not a structure and therefore does not need to have a ground rod (other than the main pole) and can simply be treated as a subpanel...

What code section do you use to quantify your feeder past the ?main pole??

 

[George Stolz]

So every time current returns on the neutral it will also simultaneously return through the electrodes, if you add other metallic items that also bond at each end they will also have neutral current (phone/coaxial/conduit?)

Okay, I get what you are saying now. Thankfully, Ohms Law covers that scenario. As long as the neutral conductor is intact, it's resistance should be far lower than the resistance to earth of the electrodes. The neutral has to open to create a shock hazard to the occupants of any of the structures.

Have you actually seen a metallic sheath on phone/coax runs after the TelCo/TvCo's demarcation point to have to rebond? The direct burial phone wire I've seen doesn't have a metallic shield to bond.

IMO, and in previous discussions about this here, it's pretty widely believed that the utility's neutral connection is more likely to open than anything downstream of the service disconnect. It appears to be far more common than the feeder to a detached structure's neutral opening.

Well, you will enjoy the new and improved 250.32 in the 2008, it reduces the viability of using the neutral conductor to the detached building as the ground-fault-clearing path to the point of extinction. I disagree with the premise, myself, but I will wire to code.

This picture [if it shows up] is an example of a violation of 250-32(B)(2).

And anyone who installs that is not a qualified installer, IMO, and probably doesn't own a code book in the first place.

 

[tryinghard]

Well I believe the bonding [parallel] is between the service side and the demarcation. I?m not positive if serving phone/coaxial bonds to an electrode in it?s service route, but it does bond to the electrode system at the building [demarcation]. So if the phone/coaxial service bonds before the demarcation it will be a parallel neutral path and it will be a very good one if they bond to the same electrode as utility power.

Now the same situation often occurs between buildings that are distributed 250-32(B)(2) & #(2) is pretty hard to ensure and I believe this is why 2008 makes it all the more an exception! Temp power poles are just that ?temporary? so this is a minor issue in that sense but if a residence has its service disconnect on a pole ? remote from the home ? this situation will most likely happen.

We?re on the same page George and I appreciate your energy on this site. I?m just trying to find reasons to eliminate objectionable current, erroneous neutral bonding, and clean up noisy signal circuitry ? many times isolated grounding is redundant (and actually IS redundant) if objectionable current exists on the grounding/EGC?s. We certainly do want to keep current only on current carrying conductors and off non-current carrying conductors, especially if we know we can.