250.30 Handbook illustration of SDS

[Isaiah]

Exhibit 250.15 NEC Handbook shows the following connections to the XO: GEC, SBJ, SSBJ and Grounded Conductor.
If I run rigid steel conduit between the transformer and the panelboard can I do away with the SSBJ since the conduit will basically do the same thing?
(Also to avoid a parallel neutral scenario)


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[Dsg319]

You wouldn’t have the neutral paralleling if you have a SSBJ and MBJ in the transformer as your neutral would be floating in panel.

I’m almost certain you can use use the conduit for your SSBJ but someone will chirp in soon with a code ref.

 

[infinity]

Yes a metal raceway can serve as the SSBJ without the need to use a wire type SSBJ.

 

[Tulsa Electrician]

View attachment 2571233
Exhibit 250.15 NEC Handbook shows the following connections to the XO: GEC, SBJ, SSBJ and Grounded Conductor.
If I run rigid steel conduit between the transformer and the panelboard can I do away with the SSBJ since the conduit will basically do the same thing?
(Also to avoid a parallel neutral scenario)


Sent from my iPhone using Tapatalk

In the pic look at where SBJ is.
It is in the transformer. I think the drawing could be better to represent actual field install.

 

[infinity]

In the pic look at where SBJ is.
It is in the transformer. I think the drawing could be better to represent actual field install.

Are you saying that the SBJ in the transformer is not an ordinary field installation?

 

[Dale001289]

View attachment 2571233
Exhibit 250.15 NEC Handbook shows the following connections to the XO: GEC, SBJ, SSBJ and Grounded Conductor.
If I run rigid steel conduit between the transformer and the panelboard can I do away with the SSBJ since the conduit will basically do the same thing?
(Also to avoid a parallel neutral scenario)


Sent from my iPhone using Tapatalk

This image gives a better idea of the actual connections


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[don_resqcapt19]

In the pic look at where SBJ is.
It is in the transformer. I think the drawing could be better to represent actual field install.

My choice of the location of the system bonding jumper is based on only one thing....what location results in the shortest grounding electrode conductor, and in many cases that resulted in the SBJ being installed in the transformer.

 

[farmantenna]

I have a question regrading this Holt image, which is excellent. I had to investigate a Fire alarm panel and power supplies trouble signal, which was a alternating normal and power loss trouble when its voltage wasn't lost at all but some type of voltage surge damaged them.

the Elec and FACP panels and transformer were in same room. I removed the xfmr cover and it didn't have the system bonding jumper as shown in the image . This xfmr installation was exactly as in the image( I don't remember the EGC from HV pnl) but it did not have a bond between the X0 and enclosure, so the panel's EGC was connected to the xfmr enclosure but not the XO. I installed a jumper between them. What kind of issues could not having the bonding jumper create?

 

[augie47]

Without the system bonding jumper you would not have stable voltage to ground and you would have no path for fault current to flow to operate the over-current device in the event of a short.'
Keep in mind the SBJ could be located in the 1st disconnecting means fed by the transformer.

 

[farmantenna]

Thanks. panel neutral and ground were isolated

 

[Tulsa Electrician]

Are you saying that the SBJ in the transformer is not an ordinary field installation?

My choice of the location of the system bonding jumper is based on only one thing....what location results in the shortest grounding electrode conductor, and in many cases that resulted in the SBJ being installed in the transformer.

I was referring to the picture that was posted in #6.

The terminal bar in the transformer bolted to the enclosure.
Netural and GEC on XO with a SBJ to the terminal bar where the SSBJ is usually terminated along with the EGC from the primary raceway.

 

[don_resqcapt19]

I was referring to the picture that was posted in #6.

The terminal bar in the transformer bolted to the enclosure.
Netural and GEC on XO with a SBJ to the terminal bar where the SSBJ is usually terminated along with the EGC from the primary raceway.

I don't see any type of issue with that installation. What are you seeing?

 

[Tulsa Electrician]

I don't see any type of issue with that installation. What are you seeing?

I was referring to the illustration of the installation.
The picture in #6 is a better representation of a field install then the hand book illustration.

The hand book illustration shows Netural,GEC,SSBJ, EGC on XO terminal bar with a SBJ to frame.
Which is legal. Very seldom ever see that in the field.

If the Terminal bar in handbook pic was not XO or isolated from the frame no need for the SBJ to frame.

That is all I was thinking.

 

[Strathead]

Are you saying that the SBJ in the transformer is not an ordinary field installation?

I think the problem is things are diagrammatic here. In most installations I have seen, there is a two or three hole lug on the XO transformer connection. One is certainly the neutral going to the panel. From there though, The GEC, the SBJ and the SSBJ can be installed in many different ways. What first threw me is, I usually mount a lug (or terminal strip) with bare metal contact to the frame of the transformer. That connection then becomes the SBJ.