Article 250.64 (D) Multiple Disconnecting Means Seperate Enclosures

[electrofelon]

I see no reason for a conductor from each disconnect. You have a MBJ in each disconnect so they are bonded to the neutral. Assuming they have a hub that would bond the nipple between the disconnect and the wireway.
Agree with electrofelon in that you are dealing with folks who don't understand he Code. You can try to convince them or comply with the silly request.

And I just want to add that there could be an issue of terminology here, grounding versus bonding. I believe this post was about the options of landing the grounding electrode conductor. There may be other reasons for a "ground wire" from The wire way to each disconnect, and that is to bond the wire away. That is a separate and independent issue from how and where the grounding electrode conductor is landed.

 

[infinity]

I've posted pics of where the ground wire from the ground rods terminate & where the water bond terminates.
I've been in discussion with the electrical sub code official. He has stated the a ground wire needs to terminate in each disconnect, then terminate back in the trough where I have the ground bar installed. He also has consulted with another electrical sub-code official and has concluded still that a ground wire needs to terminate from each service disconnect back to the common ground bar installed in the trough.

Thanks for the pics. Lets start with the terminology so we're all on the same page. The conductor to the ground rods is a GEC. You've stated that you're bonding the water piping system so the conductor to the water pipe is a bonding jumper. This is an older looking home it doesn't have a metal water pipe coming in from the street?

 

[Bigbri0104]

Thanks for the pics. Lets start with the terminology so we're all on the same page. The conductor to the ground rods is a GEC. You've stated that you're bonding the water piping system so the conductor to the water pipe is a bonding jumper. This is an older looking home it doesn't have a metal water pipe coming in from the street?

Hi Rob,

I understand terminology is critical to establish transparency.

First the wording the sub code official stated was, "each enclosure needs grounding conductors" I believe he meant "Bonding conductor or jumper." I was under the impression the bonding screw in each enclosure is establishing the bond needed to clear a fault. Essential the bonding screw is the bonding conductor or jumper he is requesting is that correct?

- The continuous GEC coming off the ground rods terminates to the grounding bar installed in the trough
- This is an older home and the water coming in is copper entering the home
- The water pipe is bonded and terminates also to the ground bar in the wireway

I hope this helps

 

[electrofelon]

Hi Rob,

I understand terminology is critical to establish transparency.

First the wording the sub code official stated was, "each enclosure needs grounding conductors" I believe he meant "Bonding conductor or jumper." I was under the impression the bonding screw in each enclosure is establishing the bond needed to clear a fault. Essential the bonding screw is the bonding conductor or jumper he is requesting is that correct?

Although the terminology is not fantastic, so perhaps I am misinterpreting what he is meaning, but no he is wrong. The gec does not need to go to the service disconnect. He needs to review 250.64.

 

[infinity]

First the wording the sub code official stated was, "each enclosure needs grounding conductors" I believe he meant "Bonding conductor or jumper." I was under the impression the bonding screw in each enclosure is establishing the bond needed to clear a fault. Essential the bonding screw is the bonding conductor or jumper he is requesting is that correct?

There's your first problem what does he mean by grounding conductors? FWIW I have no idea what that means but I can guess that he's thinking a GEC to each servcie disconnect.

Here is what's required by the NEC. You've clarified that you do not have a "water bond" because you actually have a GEC going to the water pipe electrode. You also have a GEC going to the ground rods. The GEC's can terminate at any point between the service disconnects and the service point. The two disco's are the service disconnects. The service point is where the drop connects to the servcie conductors. In between those two points is the wireway so the GEC's can both terminate in the wireway without extending anywhere else.

There is no requirement to bring the GEC's into each service disconnect once they're terminated in the wireway. Each service disconnect requires a MBJ connecting the neutral to the enclosure. The bonding screw that comes with the disconnect can be used as the MBJ.

It looks like both your meter cans and service disconnects have hubs. If so then your metal nipples do not require any additional bonding (I think that I see a bonding bushing which is fine).

The real question should be how does your ground bus in the wireway connect to the neutral and how is the neutral bonded to the wireway?

 

[Bigbri0104]

There's your first problem what does he mean by grounding conductors? FWIW I have no idea what that means but I can guess that he's thinking a GEC to each servcie disconnect.

Here is what's required by the NEC. You've clarified that you do not have a "water bond" because you actually have a GEC going to the water pipe electrode. You also have a GEC going to the ground rods. The GEC's can terminate at any point between the service disconnects and the service point. The two disco's are the service disconnects. The service point is where the drop connects to the servcie conductors. In between those two points is the wireway so the GEC's can both terminate in the wireway without extending anywhere else.

There is no requirement to bring the GEC's into each service disconnect once they're terminated in the wireway. Each service disconnect requires a MBJ connecting the neutral to the enclosure. The bonding screw that comes with the disconnect can be used as the MBJ.

It looks like both your meter cans and service disconnects have hubs. If so then your metal nipples do not require any additional bonding (I think that I see a bonding bushing which is fine).

The real question should be how does your ground bus in the wireway connect to the neutral and how is the neutral bonded to the wireway?

 

[Bigbri0104]

The ground bus/bar connects to the neutral by bonding jumper where it terminates on the ilsco tap

 

[infinity]

The ground bus/bar connects to the neutral by bonding jumper where it terminates on the ilsco tap

Thanks for the additional photos. Yes the paint under the field installed ground bar needs to be removed. Also what size is the bare bonding jumper and what size is the ungrounded service conductors?

 

[Bigbri0104]

Thanks for the additional photos. Yes the paint under the field installed ground bar needs to be removed. Also what size is the bare bonding jumper and what size is the ungrounded service conductors?

Morning Bob,
Yes, my apologies the paint needs to be removed, inside and outside? And your thoughts on what tool to remove paint? I did use 4awg copper as the bonding jumper, because that would satisfy the conductor used (250 kcmil) from chart for 250.102 (C)(1).

 

[infinity]

Yes, my apologies the paint needs to be removed, inside and outside? And your thoughts on what tool to remove paint? I did use 4awg copper as the bonding jumper, because that would satisfy the conductor used (250 kcmil) from chart for 250.102 (C)(1).

Just the paint inside that is between the wireway and the ground bus, I would use a Dremel or oscillating multi-tool. Other than that you're good now all you have to do is convince the inspector that the GEC's are not required to be installed in each service disconnect. If he still disagrees you reach out to the DCA for clarification.

Here's why you do not need to bring the GEC to each disconnecting means. 250.64(D) has three different methods to connect the GEC's to the system when there are two or more disconnects. You can use any of the three methods. Your installation complies with 250.64(D)(3) because your connection is within the wireway. Below are the applicable code sections:

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

250.64(D) Building or Structure with Multiple Disconnecting Means in Separate Enclosures.
If a building or structure is supplied by a service or feeder with two or more disconnecting means in separate enclosures, the grounding electrode connections shall be made in accordance with 250.64(D)(1), 250.64(D)(2), or 250.64(D)(3).
250.64(D)(1) Common Grounding Electrode Conductor and Taps.
A common grounding electrode conductor and grounding electrode conductor taps shall be installed. The common grounding electrode conductor shall be sized in accordance with 250.66, based on the sum of the circular mil area of the largest ungrounded conductor(s) of each set of conductors that supplies the disconnecting means. If the service-entrance conductors connect directly to the overhead service conductors, service drop, underground service conductors, or service lateral, the common grounding electrode conductor shall be sized in accordance with Table 250.66, note 1.
A grounding electrode conductor tap shall extend to the inside of each disconnecting means enclosure. The grounding electrode conductor taps shall be sized in accordance with 250.66 for the largest service-entrance or feeder conductor serving the individual enclosure. The tap conductors shall be connected to the common grounding electrode conductor by one of the following methods in such a manner that the common grounding electrode conductor remains without a splice or joint:
(1) Exothermic welding.
(2) Connectors listed as grounding and bonding equipment.
(3) Connections to an aluminum or copper busbar not less than 6 mm thick × 50 mm wide (1∕ 4 in. thick × 2 in. wide) and of sufficient length to accommodate the number of terminations necessary for the installation. The busbar shall be securely fastened and shall be installed in an accessible location. Connections shall be made by a listed connector or by the exothermic welding process. If aluminum busbars are
used, the installation shall comply with 250.64(A).
250.64(D)(2) Individual Grounding Electrode Conductors.
A grounding electrode conductor shall be connected between the grounding electrode system and one or more of the following, as applicable:
(1) Grounded conductor in each service equipment disconnecting means enclosure
(2) Equipment grounding conductor installed with the feeder
(3) Supply-side bonding jumper
Each grounding electrode conductor shall be sized in accordance with 250.66 based on the service-entrance or feeder conductor(s) supplying the individual disconnecting means.
250.64(D)(3) Common Location.
A grounding electrode conductor shall be connected in a wireway or other accessible enclosure on the supply side of the disconnecting means to one or more of the following, as applicable:
(1) Grounded service conductor(s)
(2) Equipment grounding conductor installed with the feeder
(3) Supply-side bonding jumper
The connection shall be made with exothermic welding or a connector listed as grounding and bonding equipment. The grounding electrode conductor shall be sized in accordance with 250.66 based on the service-entrance or feeder conductor(s) at the common location where the connection is made.

 

[Bigbri0104]

Just the paint inside that is between the wireway and the ground bus, I would use a Dremel or oscillating multi-tool. Other than that you're good now all you have to do is convince the inspector that the GEC's are not required to be installed in each service disconnect. If he still disagrees you reach out to the DCA for clarification.

Here's why you do not need to bring the GEC to each disconnecting means. 250.64(D) has three different methods to connect the GEC's to the system when there are two or more disconnects. You can use any of the three methods. Your installation complies with 250.64(D)(3) because your connection is within the wireway. Below are the applicable code sections:

Thanks everyone for advice and guidance. Bob, I'm going to call the sub-official and ask him why he is insisting that I use 250.64(D)(1).
I want to have a healthy conversation on his reasoning why? Is it because of too many mechanical parts "bonding screw, threads etc.." that might fail in the future if a fault condition would occur? That is the only reason I can think of for wanting me to install another bonding wire.

 

[infinity]

Is it because of too many mechanical parts "bonding screw, threads etc.." that might fail in the future if a fault condition would occur? That is the only reason I can think of for wanting me to install another bonding wire.

The issue is (at least how you've explained it) is that the inspector wants the GEC connection to be in each individual disconnect which is not required because there are three different code complaint methods permitted by the NEC to connect the GES via a GEC to the neutral in 250.64(D). If you think about it what difference does it make where the GEC connects to the neutral? Regardless of the location of the GEC connection the system will function as intended and required.

Regarding fault conditions, the SSBJ and the MBJ's are responsible for providing the low impedance path back to the source. The GEC has nothing to do with that.

 

[shortcircuit2]

Are those metal nipples/fittings between the wireway and meter, and wireway and service disconnect required to be bonded per 250.92?

Utility companies around here may frown on the wireway with spliced connections ahead of the meter. Location to steal power. I do see a stamped provision in the wireway cover for a lock.

 

[infinity]

Are those metal nipples/fittings between the wireway and meter, and wireway and service disconnect required to be bonded per 250.92?

They all appear to have a hub on one end so they're already bonded.

 

[electrofelon]

If you think about it what difference does it make where the GEC connects to the neutral? Regardless of the location of the GEC connection the system will function as intended and required.
.

I once had a GEC connected upstream from the main panel and got in an argument with an inspector. He was concerned there was "no ground" in the panel.

 

[Fred B]

I once had a GEC connected upstream from the main panel and got in an argument with an inspector. He was concerned there was "no ground" in the panel.

That is the problem with "allowed" but not often seen installations.

 

[infinity]

I once had a GEC connected upstream from the main panel and got in an argument with an inspector. He was concerned there was "no ground" in the panel.

This is a concept that escapes many electricians and inspectors due to a fundamental misunderstanding of how the connection to the GES works.

 

[electrofelon]

This is a concept that escapes many electricians and inspectors due to a fundamental misunderstanding of how the connection to the GES works.

Certainly. This continues to be a huge problem that the industry can't seem to get over. Anything "grounding" just gets lumped together, with no critical thinking about what is actually being accomplished, and its all of Paramount importance.

 

[infinity]

Certainly. This continues to be a huge problem that the industry can't seem to get over. Anything "grounding" just gets lumped together, with no critical thinking about what is actually being accomplished, and its all of Paramount importance.

Yeah I think that part of the reason is that many of us were taught using lazy incorrect language and it all gets lumped together.

As far as the connection of the GES to the system neutral if you understand the purpose in 250.4(A)(1) it should be clear that where it's connected on the line side of the service disconnect should not matter. Therefore when you analyze the installation in the OP you'll see that if you landed the GEC's in the two service disconnects or ahead of them in the wireway the tenets of the dirt worshipers will be accomplish either way.

250.4(A) Grounded Systems.
250.4(A)(1) Electrical System Grounding.
Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

 

[electrofelon]

Yeah I think that part of the reason is that many of us were taught using lazy incorrect language and it all gets lumped together.

As far as the connection of the GES to the system neutral if you understand the purpose in 250.4(A)(1) it should be clear that where it's connected on the line side of the service disconnect should not matter. Therefore when you analyze the installation in the OP you'll see that if you landed the GEC's in the two service disconnects or ahead of them in the wireway the tenets of the dirt worshipers will be accomplish either way.

But the NEC also makes it kinda confusing. For example using the tap method for services with multiple service disconnects, what is the purpose of needing a GEC tap to an additional service disconnect (assuming that neutral is sized large enough for the GEC of the entire service)? There isn't consistency in their rules.