SSBJ - where to connect

[Jpflex]

With an outdoor transformer I think it is important to address the exceptions:
250.30(A)(1) System Bonding Jumper
Exception No. 2: If a building or structure is supplied by a feeder from an outdoor separately derived system, a system bonding jumper at both the source and the first disconnecting means shall be permitted if doing so does not establish a parallel path for the grounded conductor. If a grounded conductor is used in this manner, it shall not be smaller than the size specified for the system bonding jumper but shall not be required to be larger than the ungrounded conductor(s). For the purposes of this exception, connection through the earth shall not be considered as providing a parallel path.
and if you take advantage of that exception
250.30(A)(2) Supply Side Bonding Jumper
Exception: A supply-side bonding jumper shall not be required between enclosures for installations made in compliance with 250.30(A)(1), Exception No. 2.

This is pretty much what I said from what i could remember without looking up the code word for word

 

[david]

No, the outdoor tap rule for transformer secondaries (240.21(C)(4)) would allow the OCPD to be at the building supplied, outside or inside nearest the point of entry. The result is that the feeder consists only of the circuit conductors, with the grounded conductor as the fault clearing path.

Cheers, Wayne

You're calling the secondary supply conductors originating at the transformer a feeder.

I'm looking at 250.32 (B) (1) supplied by a feeder

250.32 (B) (1) exception # 2 does not give a description of a feeder without overcurrent protection at the supply side of the feeder.

250.32 (B) (1) exception # 2 gives a description of a feeder without an equipment ground

Looking at 250.32 (B) (2) supplied by separately derived system.

I see what you described addressed in 250.32 (B) (2) (b) without overcurrent protection provided where the conductors originate.

250.30 (A) do not rebond the grounded conductor on the supply side of the system bonding conductor.

If installed,

It is the supply side bonding jumper that connects the system bonding jumper to the buildings eguipment grounding and grounding electrode system.

Imo, 250.32 (B) (2) does not identify the secondary supply conductors as a feeder and does not give permission for a system bonding conductor at the building required disconnect

 

[david]

System bonding jumper/

 

[wwhitney]

For the exception to apply the building supply would have to be a feeder.

The definition from Article 100:

Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.

With a customer-owned, outdoors transformer, the transformer is (generally) the source of a separately derived system. The conductors from there to the a building with OCPD are a feeder, regardless of the location of the first OCPD.

Cheers, Wayne

 

[david]

The definition of a feeder that originates from a service does not adress the location of the overcurrent protection.

In the same way the definition of a feeder that originates from a secondary derived system does not address the location of the overcurrent protection. Location is addressed in 250.32 (B) (2) (a) and (b).

250.32 tells us a building will have a grounding electrode system.
Single branch circuit does not need to be addressed in this discussion.
A normal branch circuit and in this discussion a normal feeder
Let's just talk about the normal feeder portion.

250.32 (B) (1) the required equipment ground and it will be the conductor that the grounding electrode conductor is bonded to

No system bonding jumper, no bonded neutral in this description of a normal feeder supply

Exception #1 previous codes. Three conductor feeder no eguipment ground. System bonding jumper was compliant and still is for existing feeders to existing buildings.

Exception # 2 addresses a normal feeder without an equipment ground.
Here 250.30 (A) (1)exception # 2. the exception is not requiring an equipment ground. Sbj in two locations

250.32 (B) (1)Exception No. 2 is an exception to a normal feeder that is required to have an equipment ground.

250.32 (B) (2) addresses the secondary supply conductors from a separately derived system. And the location of the overcurrent protection
(a) with overcurrent protection
(b) with out overcurrent protection

First 250.30(A) (1) *addresses a source locationif has overcurrent protection.
**If the source location does not have overcurrent protection.

*If the source location has a disconnect .
** if the source location does not have a disconnect.

*** if the source has neither overcurrent protection or a disconnecting means.

"The system bonding jumper shall remain with in the enclosure where it originates."

"If the source is located outside of the building or structure supplies, the system bonding jumper shall be installed at the grounding electrode conection in compliance with 250.30 (C)"

250.32 (B) (2) no longer talking about a normal feeder that was required to have an equipment ground

It is about a secondary derived transformers secondary supply conductors
(b) without overcurrent protection where the conductors originate.
No rebonding on the load side of the system bonding jumper.

The supply side bonding jumper is the connected path from the system bonding jumper to the buildings disconnecting means and to the grounding electrodes.

There is no mention of 250.30 (A)(1) exception # 2 as called out in 250.30 (B) (1) exception # 2 (building supplied by a feeder)

All that just to say when it comes to a secondary supply system.

You are eather going to have a building supplied by 250.32 (B) (1) feeder
Or
250.32 (B) (2) secondary supply system secondary supply conductors.

 

[david]

250.32 (B) (2) (a) overcurrent where the conductors originate. Makes the secondary supply conductors a feeder and sends you to 250.32 (B) (1) grounded systems supplied by a feeder.

The overcurrent protection at the location of where the conductors originate makes the secondary conductors a normal feeder.

Once it is a feeder you can apply the exception 250.32 (B) (1) exception # 2

 

[wwhitney]

All that just to say . . .

Whatever point you are trying to make is lost (at least on me) in the verbosity of your posts.

I will say that in 250.32 "Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s)," under "(B) Grounded Systems," the subdivisions of "(1) Supplied by a Feeder or Branch Circuit" and "(2) Supplied by Separately Derived System" are poorly chosen, in that they do not provide a mutually exclusive division of possibilities. Anything supplied by a separately derived system is in fact supplied by a feeder or branch circuit. The title of (1) should be something "Other than supplied by a Separately Derived System" or "Supplied by Conductors with OCPD at Their Source."

Cheers, Wayne

 

[david]

Whatever point you are trying to make is lost (at least on me) in the verbosity of your posts.

I will say that in 250.32 "Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s)," under "(B) Grounded Systems," the subdivisions of "(1) Supplied by a Feeder or Branch Circuit" and "(2) Supplied by Separately Derived System" are poorly chosen, in that they do not provide a mutually exclusive division of possibilities. Anything supplied by a separately derived system is in fact supplied by a feeder or branch circuit. The title of (1) should be something "Other than supplied by a Separately Derived System" or "Supplied by Conductors with OCPD at Their Source."

Cheers, Wayne

That's fine but I'm going to point out one other thing found in all this verbiage 250.30 (A) (1) (b) 2024 code has a new exception

installed at the first disconnecting means

Part of the last sentence "instead of the disconnecting means located at each separate source."

This exception places the first disconnecting means addressed in 250.30 (A) (1) at the location of the source.

The first disconnecting means location. 250.30 (A) (1) talks about a disconnecting means and refers you to250.30 (A,) (1) (b).

Now by the new exception the first disconnect location is said to be at the source location. At least for this exception.

 

[david]

Whatever point you are trying to make is lost (at least on me) in the verbosity of your posts.

I will say that in 250.32 "Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s)," under "(B) Grounded Systems," the subdivisions of "(1) Supplied by a Feeder or Branch Circuit" and "(2) Supplied by Separately Derived System" are poorly chosen, in that they do not provide a mutually exclusive division of possibilities. Anything supplied by a separately derived system is in fact supplied by a feeder or branch circuit. The title of (1) should be something "Other than supplied by a Separately Derived System" or "Supplied by Conductors with OCPD at Their Source."

Cheers, Wayne

Ok than tell me in your verbagel what does 250.32(B) (2) (a) and (b) mean

 

[wwhitney]

Ok than tell me in your verbagel what does 250.32(B) (2) (a) and (b) mean

OK, to paraphase:

250.32(B)(2)(a): if your SDS is away from the building, and the supply has OCPD that is upstream of the building disconnect, it's just a normal feeder, so go see the normal feeder supply section 250.32(B)(1).

250.32(B)(2)(b): otherwise, you have to comply with the normal SDS rules in 250.30(A) (which is nothing new). If your supply has an SSBJ because you're not using 250.20(A)(2) Exception, then it goes to the building GES.

Cheers, Wayne

 

[david]

OK, to paraphase:

250.32(B)(2)(a): if your SDS is away from the building, and the supply has OCPD that is upstream of the building disconnect, it's just a normal feeder, so go see the normal feeder supply section 250.32(B)(1).

250.32(B)(2)(b): otherwise, you have to comply with the normal SDS rules in 250.30(A) (which is nothing new). If your supply has an SSBJ because you're not using 250.20(A)(2) Exception, then it goes to the building GES.

Cheers, Wayne

If what you presented is true than there would be no purpose for the sub section 250.32 (B) (2).
Perhaps it should be 250.32 (B) (1) (A). Supplied by separtly derived system feeder.
I'm going to yield because of the phrase. ( If installed)
In 250.32 (B) (2) (b)
If installed, the supply side bonding jumper shall be connected to the buildings or Structures disconnecting means and to the grounding electrode(s).

 

[bobby ocampo]

One of my often referred to images from MH View attachment 2571924

Should be explained by equipotential. A single line to ground fault should be safe with equipment grounding regardless if OCPD trips or not. Just safer if circuit breaker trips. Explanation is in IEEE Green Book or in the new IEEE 3K series