electrical service grounding & bonding

[steve66]

Background: Overhead 200A, 240V/120V single phase service. Service conductors run down building to a 200A disconnect, from the disconnect to a 4 gang meter stack, and from each meter to a 100A disconnect.

Dillema: The inspector doesn't like the grounding & bonding. The grounded service conductor isn't split into separate EGS's and grounded conductors (i.e. neutral and ground) until it gets to each 100 amp disconnect. I believe it was done like this because the meter stack only has a single bus for the grounded conductor & EGC.

Does anyone see anything wrong with this?

(I'm not 100% sure I'm using the terms right. Article 250 is somewhat confusing.)

 

[bob]

Other than is doesn't meet code, no problem. You are suppose to seperate the neutral and EGC after the main switch. If the conduit is metal you would not need an EGC.

 

[infinity]

Is the 200 amp disco the service disconnect or a meter disconnection means?

 

[steve66]

Is the 200 amp disco the service disconnect or a meter disconnection means?

I'm not sure - it's purpose is to limit the current on the service to 200 amps, but there are also the 100A disconnects. Those might be the service disconnects.

Maybe a diagram will help. It shows one of the (4) 100A disconnects.



Hopefully, its readable.

 

[augie47]

Rob gave the "keyword". It's somewhat semantics but we treat it differently depending on the reason for the 200 amp main. If its' there at POCO's request as a meter disconnect you can probably connect your grounding electrodes downstream. If it's service equipment, the GEC should come from there or before.

A couple of things might help clarify:

Is the 200 amp switch (breaker) locked by POCO ?

Do you have GECs from each of fhe 100 amp breakers ?

 

[frank everingham]

harpo

harpo

if the utility requires the disconnect, as allowed in 230.82 all service grounding can be in the 100 amp disconnects. in michigan , the utility company some times requires the supply side disconnect if the service conductors are ran
a long distance on the outside of a building

 

[texie]

Since the 200 disconnect is also an OCPD I say this is the service disconnect point and the inspector is right. If it was ONLY a disconnect it may be arguable.

 

[augie47]

Texie, you have a good point. I have never known POCO to use a breaker for this purpose. As you say, if it's there for over-current protection which the OP mentioned, the inspector is correct. GEC connections must be made at or prior to the 200 amp OCP.

On a side note, most if not all non-fuse disconnects have a 10k rating. May not be an issue here but it's an interesting situation to discuss with POCO when they require one.

 

[steve66]

Is the 200 amp switch (breaker) locked by POCO ?

The cover will have a utility tag to seal the cover closed. The breaker handle itself probably wont be locked.

Do you have GECs from each of fhe 100 amp breakers ?

GEC's -grounding electrode conductors, right? The wires that go to the ground rod and water pipe? Right now those are ran from the 200 amp disconnects.

Steve

 

[steve66]

Rob gave the "keyword". It's somewhat semantics but we treat it differently depending on the reason for the 200 amp main. If its' there at POCO's request as a meter disconnect you can probably connect your grounding electrodes downstream. If it's service equipment, the GEC should come from there or before.

OK, but my biggest question is where can I split the service neutral wire into separate neutral and ground wires? Does that have to occur in the same enclsoure that the GEC comes from?? In other words, where do I have to go from a 3 wire system to a 4 wire system?

 

[augie47]

Separating the equipment grounds and neutrals is required at any location after the service disconnect.
(There are exceptions, one of which may cover your meter in 250.142).
You have a unique situation as a determination must be made as the which device(s) is your actual service equipment and if you do actually have a POCO meter disconnect.
It may take a discussion between you, the inspector and POCO.
Locally the 200 amp disconnect would probably considered the service equipment.

 

[steve66]

Separating the equipment grounds and neutrals is required at any location after the service disconnect.
(There are exceptions, one of which may cover your meter in 250.142).
You have a unique situation as a determination must be made as the which device(s) is your actual service equipment and if you do actually have a POCO meter disconnect.
It may take a discussion between you, the inspector and POCO.
Locally the 200 amp disconnect would probably considered the service equipment.

OK, thanks for the code refrence. That helps a lot.

I think the first disconnects are the service disconnects.

 

[jumper]

I think the first disconnects are the service disconnects.

Why? Does the 200 amp disco have OCPD? If so, I missed it.

 

[augie47]

Why? Does the 200 amp disco have OCPD? If so, I missed it.

I assumed it did have OCP as his drawing shows it being a breaker and he mentioned it being there to limit current.

 

[steve66]

Why? Does the 200 amp disco have OCPD? If so, I missed it.

Yes, its a circuit breaker.

I didn't mention this earlier, but the one-line only shows one service drop. There are actually 3 identical service drops, each feeding a 200A circuit breaker, and 4 meters.

So there are actually (12) of the 100 amp circuit breakers. As a result, I think the 200 amp circuit breakers need to be considered service disconnects to keep from being over the limit of 6 disconnecting means for a single building.

 

[kwired]

Yes, its a circuit breaker.

I didn't mention this earlier, but the one-line only shows one service drop. There are actually 3 identical service drops, each feeding a 200A circuit breaker, and 4 meters.

So there are actually (12) of the 100 amp circuit breakers. As a result, I think the 200 amp circuit breakers need to be considered service disconnects to keep from being over the limit of 6 disconnecting means for a single building.

I totally agree with that.
I believe the neutral is allowed to be bonded in those meters if they are located adjacent to the service disconnecting means the grounded conductor is no smaller than would be required by 250.122(which I don't know why is there because this is minimum size of grounded conductor anyway in that kind of circumstance) and there is no ground fault protection. See 250.142(B) exception 2.

I myself may still pass the neutral through the meter without connection to any bonding or possibly use non metallic raceways or cables to prevent neutral current from being carried through unintended paths

 

[T.M.Haja Sahib]

Background: Overhead 200A, 240V/120V single phase service. Service conductors run down building to a 200A disconnect, from the disconnect to a 4 gang meter stack, and from each meter to a 100A disconnect.

Dillema: The inspector doesn't like the grounding & bonding. The grounded service conductor isn't split into separate EGS's and grounded conductors (i.e. neutral and ground) until it gets to each 100 amp disconnect. I believe it was done like this because the meter stack only has a single bus for the grounded conductor & EGC.

Does anyone see anything wrong with this?

(I'm not 100% sure I'm using the terms right. Article 250 is somewhat confusing.)

Yes. The 200A circuit breaker should be provided with GEC and the EGC should start from there, because the meters, 100A breakers etc., are in the feeder circuit from the 200A circuit breaker as the service disconnecting means and neutral should not be bonded to the meter and 100A breaker enclosures.

 

[T.M.Haja Sahib]

Yes, its a circuit breaker.

I didn't mention this earlier, but the one-line only shows one service drop. There are actually 3 identical service drops, each feeding a 200A circuit breaker, and 4 meters.

So there are actually (12) of the 100 amp circuit breakers. As a result, I think the 200 amp circuit breakers need to be considered service disconnects to keep from being over the limit of 6 disconnecting means for a single building.

Not necessarily. The Code speaks of 2 to 6 service disconnects per service only. If more than one service is required and permitted by the Code, more than one set of 2 to 6 service disconnects can be provided in a single building in the same location.

 

[cadpoint]

Yike I didn't like your stectch, nothing personal but seemed scary.

MH just did a recent letter on this very thing - 240.21(B)(1)(4) 10-Foot Feeder Tap

 

[T.M.Haja Sahib]

MH just did a recent letter on this very thing - 240.21(B)(1)(4) 10-Foot Feeder Tap

Sorry, it does not seem to be applicable to the sketch of the OP i.e there is no tap of tap in it.