Service disconnect bonding for detached structure question

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ritelec

Senior Member
Location
Jersey
Hello,

Am I right in my head?

Two separate buildings (cottages).

There is a cottage (A), it has the service over head to it. The service has two seu's down to two meters on cottage (A).

Cottage (A) has a meter then goes into the cottage (A) (guessing main breaker panel).
On cottage (A) there's also a meter to a 100 amp disconnect (breaker). That 100 amp disconnect (breaker) feeds cottage (B). There are four conductors in a underground conduit feeding cottage (B) (those conductors are in plumbing pvc but thats something else.)

I didn't see any ground rods for cottage (A) and theres one rod for the cottage (B) disconnect (breaker).

The cottage (A) has water pipe (it's under a hatch which I couldn't get to, not sure if it has ground to (A) panel, but sure there's no ground to (B) disconnect from opening (B) disconnect)

Would I be correct to see it as, even though cottage (B) has nothing to do with cottage (A) except for the mounting of it's equipment and first over current protection, that BOTH cottage (A) main breaker panel and cottage (B) main breaker disconnect would need to be bonded to ground rod(s) at cottage (A) AND cottage (A) water meter ground electrode ? Then "at" cottage (B), the egc at that panel would get bonded to the water system at cottage (B) and ground rod(s) at cottage (B) with the neutral floating.


Confirming, Thank you.

Rich
 

ritelec

Senior Member
Location
Jersey
Funny. :- )


Thank you.



Pondering.


At service. The size of the ground rod electrode conductors would not be required to be
larger than # 6

The water electrode conductor size is sized to the service conductor ( which I believe is to one of the 100 amp seu's and not the two seu's combined )

At cottage (B), does the wire size for bonding the water system equal the egc size.

For grins?? If there was a 30 or 40 amp feed to the cottage (B) would 6 awg still be required to the ground rod(s) ?


For grins grins?? If there was a 30, 60 or 200 amp circuit (not a feeder) going to a detached structure, would ground rods and water system bonding be required ?


Earmuffs ;- )
 

shortcircuit2

Senior Member
Location
South of Bawstin
Hello,

Am I right in my head?

Two separate buildings (cottages).

There is a cottage (A), it has the service over head to it. The service has two seu's down to two meters on cottage (A).

Cottage (A) has a meter then goes into the cottage (A) (guessing main breaker panel).
On cottage (A) there's also a meter to a 100 amp disconnect (breaker). That 100 amp disconnect (breaker) feeds cottage (B). There are four conductors in a underground conduit feeding cottage (B) (those conductors are in plumbing pvc but thats something else.)

I didn't see any ground rods for cottage (A) and theres one rod for the cottage (B) disconnect (breaker).

The cottage (A) has water pipe (it's under a hatch which I couldn't get to, not sure if it has ground to (A) panel, but sure there's no ground to (B) disconnect from opening (B) disconnect)

Would I be correct to see it as, even though cottage (B) has nothing to do with cottage (A) except for the mounting of it's equipment and first over current protection, that BOTH cottage (A) main breaker panel and cottage (B) main breaker disconnect would need to be bonded to ground rod(s) at cottage (A) AND cottage (A) water meter ground electrode ? Then "at" cottage (B), the egc at that panel would get bonded to the water system at cottage (B) and ground rod(s) at cottage (B) with the neutral floating.

Question:
If cottage (B) were to be a distance from cottage (A)...say 400+ feet away(for example), and we add a whole house generator connected as non-separately derived at cottage (B)...and the grounded conductor to ground bond is all the way at cottage (A) service disconnect...is this a code violation or concern of the ground fault path on the EGC for the stand by generator being that the system bond is so far away?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Funny. :- )
At service. The size of the ground rod electrode conductors would not be required to be
larger than # 6

For the portion that only connects to the rods, yes.

The water electrode conductor size is sized to the service conductor ( which I believe is to one of the 100 amp seu's and not the two seu's combined )

Per table 250.66, yes. If there is no service conductor anywhere that is larger than the 100A SEU, then you can size it to that.

At cottage (B), does the wire size for bonding the water system equal the egc size.

No, it is sized to 250.66, but based on the feeder between cottage A and B (not the service conductors).

For grins?? If there was a 30 or 40 amp feed to the cottage (B) would 6 awg still be required to the ground rod(s) ?

No, but the minimum size for a GEC is 8 awg, and then it is required to be run in RMC, IMC, PVC, RTRC, EMT, or cable armor. So there's not much to be gained by not using bare solid #6. By the way, the 6awg must free from exposure to physical damage (whatever that means) or it requires the same kind of protection.

See 250.64(B).

For grins grins?? If there was a 30, 60 or 200 amp circuit (not a feeder) going to a detached structure, would ground rods and water system bonding be required ?

No to the ground rod(s), if the circuit has an EGC.
Yes to the water pipe bonding.
 

102 Inspector

Senior Member
Location
N/E Indiana
Occupation
Inspector- All facets
If the overhead service goes to Cottage A, then splits to a duplex meter assembly, then goes into to Cottage A and to a disconnect outside to Cottage B, would this not be a violation of 230.72 grouping of disconnects? Since the disconnects need to shut off all the power from the service, it would require an additional disconnect prior to entering cottage A or place the disconnect to cottage B inside beside the other main panel. I guess it comes down to the interpretation of grouped allows in this case. I feel you need to stand in one area and be able to see and reach all the disconnects that are served by the service coming to the structure. Am I missing something on this call?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
If the overhead service goes to Cottage A, then splits to a duplex meter assembly, then goes into to Cottage A and to a disconnect outside to Cottage B, would this not be a violation of 230.72 grouping of disconnects? Since the disconnects need to shut off all the power from the service, it would require an additional disconnect prior to entering cottage A or place the disconnect to cottage B inside beside the other main panel. I guess it comes down to the interpretation of grouped allows in this case. I feel you need to stand in one area and be able to see and reach all the disconnects that are served by the service coming to the structure. Am I missing something on this call?

If the disconnect for Cottage A is inside and the disconnect for Cottage B is outside, then I agree. They ought to have a disconnect for each meter outside at the meters. (They could have both of them together inside but it doesn't sound like that would make practical sense in this case.)

Not that it's what the OP asked about.
 

Smart $

Esteemed Member
Location
Ohio
If the disconnect for Cottage A is inside and the disconnect for Cottage B is outside, then I agree. They ought to have a disconnect for each meter outside at the meters. (They could have both of them together inside but it doesn't sound like that would make practical sense in this case.)

Not that it's what the OP asked about.
Ahhh, but here's the rub. When you split the service entrance conductor in two to go to the two meters, you effectively create two service entrance conductors. The two to six disconnect grouping rule does not apply because each service entrance conductor only has one disconnect.
 

shortcircuit2

Senior Member
Location
South of Bawstin
If the overhead service goes to Cottage A, then splits to a duplex meter assembly, then goes into to Cottage A and to a disconnect outside to Cottage B, would this not be a violation of 230.72 grouping of disconnects? Since the disconnects need to shut off all the power from the service, it would require an additional disconnect prior to entering cottage A or place the disconnect to cottage B inside beside the other main panel. I guess it comes down to the interpretation of grouped allows in this case. I feel you need to stand in one area and be able to see and reach all the disconnects that are served by the service coming to the structure. Am I missing something on this call?

The disconnect for cottage B doesn't feed any wiring in cottage A, so grouping isn't required.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Ahhh, but here's the rub. When you split the service entrance conductor in two to go to the two meters, you effectively create two service entrance conductors. The two to six disconnect grouping rule does not apply because each service entrance conductor only has one disconnect.

Okay, I'll buy that for a $1.
 

kwired

Electron manager
Location
NE Nebraska
Two meter sockets on a pole with no (service) disconnecting means is just a wide point(s) in the service disconnecting means.

You still have service conductors at the two structures being fed and the only relation between them as far as an electrician may be concerned is that they may be owned by the same person, otherwise they are separate structures each supplied by a service.
 

david

Senior Member
Location
Pennsylvania
Each service drop or lateral shall supply only one set of service-entrance conductors.

I do not have a real problem with it, I do not see where 230.40 specifically allows for it.

I see exception three allowing for it for a single family dwelling and a separate structure for the dwelling garage or some other utility structure for the dwelling
 

david

Senior Member
Location
Pennsylvania
Hello,
Am I right in my head?
Cottage (A) has a meter then goes into the cottage (A) (guessing main breaker panel).
On cottage (A) there's also a meter to a 100 amp disconnect (breaker). That 100 amp disconnect (breaker) feeds cottage (B). There are four conductors in a underground conduit feeding cottage (B) (those conductors are in plumbing pvc but thats something else.)


230.40 Exception No. 2: grouping of the service disconnects from a single service drop.

I think if the service disconnect for cottage A. was grouped outside with the disconnect for cottage B. the installation could come into compliance with 230.40 Exception No. 2 and I agree that both cottage A. and cottage B. would need a grounding electrode system
 

Smart $

Esteemed Member
Location
Ohio
Each service drop or lateral shall supply only one set of service-entrance conductors.

I do not have a real problem with it, I do not see where 230.40 specifically allows for it.

I see exception three allowing for it for a single family dwelling and a separate structure for the dwelling garage or some other utility structure for the dwelling

230.40 Exception No. 2: grouping of the service disconnects from a single service drop.

I think if the service disconnect for cottage A. was grouped outside with the disconnect for cottage B. the installation could come into compliance with 230.40 Exception No. 2 and I agree that both cottage A. and cottage B. would need a grounding electrode system
Each cottage under Code is considered a single family dwelling. 230.40 Exception No. 3 permits a service entrance conductor from a single drop to each cottage.
 

Smart $

Esteemed Member
Location
Ohio
yes as long as they are on the same premise.
Under the NEC, it doesn't matter. Premise(s) is not defined by the NEC and is not limited to a single parcel of land as distinguished by the local government's land management bureau.
 
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