Grounded Conductor required?

[xformer]

Does the code require the grounded conductor be brought to the first means of disconnect on a separately Derived System?

 

[Dale001289]

Does the code require the grounded conductor be brought to the first means of disconnect on a separately Derived System?

yes, if system is grounded, See 250.24(C)

 

[augie47]

normally yes but basically depends on the voltages see 250.20(B)

 

[ActionDave]

The first paragraph of 250.30 does not include 250.24 in the list of other articles that apply, so I say no.

 

[Dale001289]

The first paragraph of 250.30 does not include 250.24 in the list of other articles that apply, so I say no.

If the grounded conductor from a separately derived system (i.e. transformer) is not included with service conductors a ground fault has no path back to the Xfmr XO (or corner grounded delta) -- until it goes phase to phase.

 

[ActionDave]

If the grounded conductor from a separately derived system (i.e. transformer) is not included with service conductors a ground fault has no path back to the Xfmr XO (or corner grounded delta) -- until it goes phase to phase.

You can bond the grounded conductor in the transformer.

 

[Dale001289]

You can bond the grounded conductor in the transformer.

Of course, but the grounded conductor also has to be routed with the secondary conductors to the CB or fused switch.

 

[augie47]

You can bond the grounded conductor in the transformer.

:thumbsup: excellent point. In reading the OP I concerned myself with the need to "ground" the system and not the need to actually bring the conduct or to the disconnect.

 

[augie47]

Of course, but the grounded conductor also has to be routed with the secondary conductors to the CB or fused switch.

why ? if its not needed

 

[packersparky]

If the grounded conductor from a separately derived system (i.e. transformer) is not included with service conductors a ground fault has no path back to the Xfmr XO (or corner grounded delta) -- until it goes phase to phase.

I agree with Action Dave. The neutral is not required to be brought to the disconnect, but a supply side bonding jumper is required from the transformer to the disconnect. See 250.30(A)(2)

 

[infinity]

I agree with Action Dave. The neutral is not required to be brought to the disconnect, but a supply side bonding jumper is required from the transformer to the disconnect. See 250.30(A)(2)

I agree also, you would only need to bring it to the disconnect if that is where you're installing the system bonding jumper.

 

[Dale001289]

I agree with Action Dave. The neutral is not required to be brought to the disconnect, but a supply side bonding jumper is required from the transformer to the disconnect. See 250.30(A)(2)

a 'grounded conductor' is not necessarily a neutral - could be a non-current carrying corner or center grounded delta. The grounded conductor's only purpose is to provide fault path for service.
Supply side bonding jumper will not suffice for the grounded conductor unless it's also bonded to the xfmr windings. For example, Exhibit 250.15 Handbook

 

[packersparky]

I agree also, you would only need to bring it to the disconnect if that is where you're installing the system bonding jumper.

I believe you need to bring the SSBJ to the disconnect no matter where the system bonding jumper is installed.

 

[Dale001289]

I believe you need to bring the SSBJ to the disconnect no matter where the system bonding jumper is installed.

Agreed. But if its not bonded to the windings you'll need the grounded conductor as well, this is the only way the service CB will trip upon ground fault.

 

[infinity]

I believe you need to bring the SSBJ to the disconnect no matter where the system bonding jumper is installed.

It could be a metallic raceway. Also how does that impact the need to bring in the grounded conductor?

 

[augie47]

I believe you need to bring the SSBJ to the disconnect no matter where the system bonding jumper is installed.

agree, The supply-side bonding jumper would be needed to bond the transformer and disconnect regardless of the location of the system bonding jumper but the grounded conductor only needs to be routed to the location of the system bonding jumper

 

[packersparky]

It could be a metallic raceway. Also how does that impact the need to bring in the grounded conductor?

The SSBJ could be a non-flexible metallic raceway. The grounded conductor only needs to be brought to the disconnect if that is where you choose to install the system bonding jumper, or you are serving neutral loads.

 

[infinity]

The SSBJ could be a non-flexible metallic raceway. The grounded conductor only needs to be brought to the disconnect if that is where you choose to install the system bonding jumper, or you are serving neutral loads.

Agreed, I think I said part of that in post #11.

 

[packersparky]

Agreed, I think I said part of that in post #11.

I read the word "it" in post #11 as meaning the SSBJ, I know now that "it" was referring to the grounded conductor.

 

[packersparky]

Agreed. But if its not bonded to the windings you'll need the grounded conductor as well, this is the only way the service CB will trip upon ground fault.

By definition, the system bonding jumper is the connection between the SSBJ and the grounded conductor. The connection can be made in the transformer and the grounded conductor would not need to be brought to the disconnect.