Ground Rods

[Dennis Alwon]

Imagine a service lateral to a building that goes into a wireway at the front of a building and feeds 4 meter/mains. The service conductors are then spliced in the wireway and continue in conduit, on the building, around the corner to the right side of the building where another set of 4 meter/mains are installed. This continues to the other 2 sides of the building.

1. Is this one service? As I understand it the answer is YES

2. Is the install legal if it is one service and there are 16 service disconnects that are not even grouped?

3. If it is compliant then would ground rods be needed at each side of the building? I know it may be a good idea but I am looking for code.

If you know code sections that would be useful ---Thanks

 

[electrofelon]

I say its almost certainly one service, unless you get into some funky non typical service point locations - i.e the conductors wrapping the building are utility and the service points are the taps.

I think it could be compliant under 230.40 Ex #1. NEC doesnt define "occupancy" so might want to check what the local definition is.

Regarding grounding, IMO you still use 250.64(D) and would probably want to use the "common location" method.

 

[romex jockey]

Well that's interesting Den....a similarity might be wraping SE cable around a structure, the GE & GEC theory being the shortest/closest 'drain' for mother nature .....~RJ~

 

[electrofelon]

Consider this simpler but analogous situation may make it clearer:

Here it is common to have, say, a three floor apartment building with a unit on each floor, and a three gang meter socket with no disconnects. Run a set of service conductors to each floor ("occupancy") to a main breaker service panel. Utilizing 230.40 Ex 1 doesnt change the system grounding: you can ground the service conductors before they split, or use the tap method to each service disconnect.

Now, one could also put 2-6 grouped service disconnects on each floor/occupancy. The only thing different about Dennis' situation is the 4 disconnects dont appear to be serving ONE occupancy, nor IN each occupancy, so maybe its a bit sticky, although the wording "......run to each occupancy, or group of occupancies " seems to allow some flexibility.

 

[romex jockey]

It would appear that 230.41 ex1 HB commentary allows for multiple locations w/out limit on numer of disco's , as long as 'plaque or directory' meets ahj approval

~RJ~

 

[Dennis Alwon]

It would appear that 230.41 ex1 HB commentary allows for multiple locations w/out limit on numer of disco's , as long as 'plaque or directory' meets ahj approval

~RJ~

I think you mean 230.40 but I don't see how that applies. The commentary specifically mentions sets of service drops, overhead conductors, etc. My thread is about one service lateral coming to the building.

 

[romex jockey]

I think you mean 230.40 but I don't see how that applies. The commentary specifically mentions sets of service drops, overhead conductors, etc. My thread is about one service lateral coming to the building.

methinks your right Den, checking out all the HB pictoral scenario exhibits 1-13 in the begining of art 230.....still not seeing what you've described....~RJ~

 

[don_resqcapt19]

I think you mean 230.40 but I don't see how that applies. The commentary specifically mentions sets of service drops, overhead conductors, etc. My thread is about one service lateral coming to the building.

Your service lateral is supplying multiple sets of service entrance conductors.
The exception permits each occupancy to have its own set of service entrance conductors and each of those sets of service entrance conductors are permitted to have up to six service disconnects. There is no requirement that the service disconnects for one set of service entrance conductors be located with the service disconnects for any other set of service entrance conductors.

 

[Dennis Alwon]

Your service lateral is supplying multiple sets of service entrance conductors.
The exception permits each occupancy to have its own set of service entrance conductors and each of those sets of service entrance conductors are permitted to have up to six service disconnects. There is no requirement that the service disconnects for one set of service entrance conductors be located with the service disconnects for any other set of service entrance conductors.

Okay if that is the case is a ground rod required at each service disconnect or just at the first. it appears it would be needed at each set of discos.

 

[electrofelon]

Okay if that is the case is a ground rod required at each service disconnect or just at the first. it appears it would be needed at each set of discos.

I don't see any wording in 250.64 changing anything based on which set of SEC a disconnect belongs to or how they are or are not grouped. You need 1 GES connected to the service by the common location or the tap method to each service disconnect. That's the way I see it.

 

[Dennis Alwon]

That was my first thought also--- one grounding electrode conductor. However, It seems odd that if you had 4 service laterals from the same transformer on the building then each would need a grounding electrode conductor however, with one lateral feeding around to each set you only need one gec

 

[electrofelon]

That was my first thought also--- one grounding electrode conductor. However, It seems odd that if you had 4 service laterals from the same transformer on the building then each would need a grounding electrode conductor however, with one lateral feeding around to each set you only need one gec

I have always been a little unclear how to ground buildings with multiple services. 250.64(D) does seem to only apply to multiple service disconnects within the same service. I usually just use the "GEC busbar" method in (D)(1)(3) even though its seems not technically correct. 250.58 would seem to require a GEC to the same GES for each service, as you note.

 

[Jamesco]

Imagine a service lateral to a building that goes into a wireway at the front of a building and feeds 4 meter/mains. The service conductors are then spliced in the wireway and continue in conduit, on the building, around the corner to the right side of the building where another set of 4 meter/mains are installed. This continues to the other 2 sides of the building.

1. Is this one service? As I understand it the answer is YES

2. Is the install legal if it is one service and there are 16 service disconnects that are not even grouped?

3. If it is compliant then would ground rods be needed at each side of the building? I know it may be a good idea but I am looking for code.

If you know code sections that would be useful ---Thanks

Wow! Seems like a mess to me.

Imagine a service lateral to a building that goes into a wireway at the front of a building and feeds 4 meter/mains

I assume the service entrance neutral conductor is bonded to the metal wireway and the 4 mains enclosures. Ground rod connects to the grounded neutral conductor.
Is that correct?

[
The service conductors are then spliced in the wireway and continue in conduit, on the building, around the corner to the right side of the building where another set of 4 meter/mains are installed.

Metallic conduit? If yes I can't see how you can bond/ground the feeder neutral again. I assume you won't. Or am I missing something?

 

[Dennis Alwon]

Wow! Seems like a mess to me.

I assume the service entrance neutral conductor is bonded to the metal wireway and the 4 mains enclosures. Ground rod connects to the grounded neutral conductor.
Is that correct?

I assume also-- not my job

Metallic conduit? If yes I can't see how you can bond/ground the feeder neutral again. I assume you won't. Or am I missing something?

These aren't feeders going to each set of meters. Again not my job

 

[romex jockey]

this just reeks of an architect ........~RJ~

 

[jaggedben]

I don't see any wording in 250.64 changing anything based on which set of SEC a disconnect belongs to or how they are or are not grouped. You need 1 GES connected to the service by the common location or the tap method to each service disconnect. That's the way I see it.

:thumbsup:

I would probably connect the GEC in the first wireway (not in any disconnect). Grounding is overrated.

 

[don_resqcapt19]

Okay if that is the case is a ground rod required at each service disconnect or just at the first. it appears it would be needed at each set of discos.

It appears that 250.25(D) requires a GEC at each service disconnect.

 

[Dennis Alwon]

It appears that 250.25(D) requires a GEC at each service disconnect.

Thanks Don... I felt like it ought to be like that but couldn't find the section

 

[Jamesco]

It appears that 250.25(D) requires a GEC at each service disconnect.

Then the conduit in Dennis Alwon's posted message must be PVC.

If metallic there will be the unbalanced load neutral current also flowing on the conduit back to the source. What does the NEC say about that?

The service conductors are then spliced in the wireway and continue in conduit, on the building, around the corner to the right side of the building where another set of 4 meter/mains are installed. This continues to the other 2 sides of the building.

.

 

[Dennis Alwon]

Funny thing is the electrician that told me about this install had it all wrong but I still think it is an interesting question. I just spoke with the inspector and got the real story...