Dale001289
Senior Member
- Location
- Georgia
NEC requires a white (or grey) grounded conductor sized per T250.102 to be brought into the Service for fault path.
Grounded Conductor required?
- Thread starter xformer
- Start date
- Status
NEC requires a white (or grey) grounded conductor sized per T250.102 to be brought into the Service for fault path.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes but I don't believe we're discussing a service.
Dale001289
Senior Member
- Location
- Georgia
If the conductors originate from a transformer secondary I believe it applies regardless
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and services don't required supply side bonding jumpers which basically is doing the job of the grounded conductor being brought to a service where there is no load. So you have similar animals under a different name.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I don't see anything in this thread that would indicate that a service is involved, the OP even mentions SDS. An SDS and a service are two different things although some believe that they are treated the same.
Dale001289
Senior Member
- Location
- Georgia
I still believe a dedicated white grounded conductor is required to be run with circuit conductors from all transformer LV secondaries to panels, disconnects etc even if no phase to neutral loads exist.
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Dale001289
Senior Member
- Location
- Georgia
and I, for one, will gladly enforce that on inspections if you only give me a valid Code reference.
"Dale says so" will not work on my rejection notices
Fine - if you can explain how a CB will trip or fuse will blow without a fault path from the device back to the transformer I will gladly rescind my last post
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packersparky
Senior Member
- Location
- Wisconsin
- Occupation
- Inspector
The fault path is the SSBJ. It is connected to the normally non-current carrying metal parts on the secondary side including the EGC's. The fault returns to the transformer on the SSBJ, through the system bonding jumper, and the overcurrent device opens.
Think of it as an EGC, but it can't be called and EGC because it does not have an an overcurrent device ahead of it. That is why it is sized in accordance with 250.102(C) and not 250.122.
Dale001289
Senior Member
- Location
- Georgia
Where line to neutral loads are present, for example a delta-wye XFMR, the grounded conductor (must be white) carries unbalanced current from the panelboard to the XO whereas the SSBJ does not -its for bonding between Ground and Neutral busses (sometimes at the panel board or may go directly back to XFMR from the ground bus)
If no neutral loads are present (all 3 phase loads for example) the white conductor is still required - even if the XFMR is corner or center grounded from one winding.
The SSJB may in effect do the same thing as the grounded conductor but the code still wants to see a dedicated white conductor from the XFMR to service or panelboard neutral bar (Ref250.24.)
For branch circuits, containing current carrying neutral conductors such as lighting, receptacles etc, the EGC becomes the primary fault path since it contains the lowest path of impedance as explained in 250.134 Handbook.
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packersparky
Senior Member
- Location
- Wisconsin
- Occupation
- Inspector
Services and SDS's are not the same things. See the definitions. This is not a service. 250.24 does not apply. 250.30 applies and does not require the grounded conductor to be brought to the disconnect for SDS's.
Dale001289
Senior Member
- Location
- Georgia
I don’t see anything that states the Grounded conductor can be omitted for SDS’s.
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- Occupation
- Licensed Electrician
That doesn't matter. You are not required to bring it. The code is not a design manual, although it lurches that way every cycle.
It's also not needed to clear a fault. If the SDS does not have any line to neutral loads then a line to neutral fault is never going to happen.
packersparky
Senior Member
- Location
- Wisconsin
- Occupation
- Inspector
And I don't see anything that states the grounded conductor has to be brought to the disconnect for SDS's in 250.30. As Augie asked, What code section would an inspector cite as a violation?
Dale001289
Senior Member
- Location
- Georgia
Yes you are required to bring it both for line to neutral loads and yes to clear a fault - with or without line to neutral loads.
A ground fault can occur downstream phase to conduit for example it doesn’t need a neutral to go to ground on branch circuits.
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Dale001289
Senior Member
- Location
- Georgia
Would you rely on the SSBJ to handle unbalanced loads including harmonics...answer is “No” - the grounded conductor does that but it has to be present in order to function
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packersparky
Senior Member
- Location
- Wisconsin
- Occupation
- Inspector
As was already stated, if line to neutral loads are served by the SDS, the grounded conductor would have to brought to the disconnect.
Unbalanced loads and harmonics have nothing to do with this discussion. This discussion is about clearing faults. Clearing faults in a SDS is the job of the SSBJ.
If a SDS is not serving line to neutral loads, and the system bonding jumper is located at the SDS, there is no requirement for the grounded conductor to be brought to the disconnect if a SSBJ is installed to the disconnect.
Last edited:
Dale001289
Senior Member
- Location
- Georgia
Its impossible to separate ‘unbalanced loads and harmonics’ from a discussion about grounded systems, neutrals and SDS’s -
If you go back a few of my posts I said the SSBJ would essentially do the same thing as the grounded conductor for corner grounded systems where no line to neutral loads exist. I also said the code still requires a white conductor to be run - from the corner on a grounded delta secondary to the panel or disconnect. I believe article 250.30 supports this.
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