Transformer grounding detail

Status
Not open for further replies.
jaggedben said:
THE DRAWING DOES NOT SHOW ONE AT THE TRANSFORMER.

Are you just assuming there's a factory installed jumper in the transformer? If that's your concern then ask the person who submitted the drawing about it. Maybe they know something about their transformer that you don't.
Click to expand...

Attached this post: See the red line that has arrow point that has G.

Also see the red line that has arrow point N.

N is neutral and G is equipment grounding conductor primary.

You see that G is bonded to xfmr case. You see that N is bonded to xfmr case.

You see that N is connected to xfmr x0. Follow red line labeled N to see that to center of wye.

You have second N to G bond at xfmr

0f7313e56895cfe07b0d76b536c52582.jpg



Sent from my iPhone using Tapatalk
 
jap said:
Yes there is, and, there is an absolute ton of parallel return paths just like this everywhere you look.

You see it on almost every electrical service around where the service conductors between the utility meters, transformers etc,,, and the service disconnect are contained in a conductive conduit.

JAP>
Click to expand...

This is not service. This is at load side of main service disconnect.


NEC 2017 Article 250.30 system bonding jumper can be Either at transformer or secondary overcurrent protection. Where it says both places?


Sent from my iPhone using Tapatalk
 
There's only one.

You literally only drew one red line that ends at XO. XO is the neutral point of the secondary.

How are you misunderstanding this?

You understand that neutral secondary current only flows back to XO, right?
 
personally I'd still bond the XO to the transformer chassis. that way there is a definite path to an uninterrupted earth reference. I'd say your way would work but isn't as fool proof.
 
hhsting said:
NEC 2017 Article 250.30 system bonding jumper can be Either at transformer or secondary overcurrent protection. Where it says both places?
Click to expand...
There is only one bonding jumper that is at the panel. There is a GEC to the transformer case and one to the panel not two SBJ's.
 
hhsting said:
Attached this post: See the red line that has arrow point that has G.

Also see the red line that has arrow point N.

N is neutral and G is equipment grounding conductor primary.

You see that G is bonded to xfmr case. You see that N is bonded to xfmr case.

You see that N is connected to xfmr x0. Follow red line labeled N to see that to center of wye.

You have second N to G bond at xfmr

0f7313e56895cfe07b0d76b536c52582.jpg



Sent from my iPhone using Tapatalk
Click to expand...
All of those grounds are AFTER the neutral /XO bond.
 
hhsting said:
Attached this post: See the red line that has arrow point that has G.

Also see the red line that has arrow point N.

N is neutral and G is equipment grounding conductor primary.

You see that G is bonded to xfmr case. You see that N is bonded to xfmr case.

You see that N is connected to xfmr x0. Follow red line labeled N to see that to center of wye.

You have second N to G bond at xfmr

0f7313e56895cfe07b0d76b536c52582.jpg



Sent from my iPhone using Tapatalk
Click to expand...
That is in NO WAY a second neutral to ground connection. The only neutral to ground connection is shown at the panel. A path via a GEC or EGC does not make a neutral to ground connection.
 
jaggedben said:
There's only one.

You literally only drew one red line that ends at XO. XO is the neutral point of the secondary.

How are you misunderstanding this?

You understand that neutral secondary current only flows back to XO, right?
Click to expand...

I see. So all thats missing is supply side bonding jumper then? You cant have effective fault current path thru earth no?


Sent from my iPhone using Tapatalk
 
The GEC bonding jumper from the transformer case to the ground rod is not code required, but it is not prohibited either. My personal opinion is that it needs an EGC (or maybe a SSBJ?) between the transformer case and the panelboard.
 
Last edited:
Tulsa Electrician said:
Would this look better to you.
Drawing Kinda crude.
Click to expand...

No and Yes

Yes but i cant just say that remove cable from rod tomxfmr case and provide ssbj between panel and xfmr. Engineer says whats wrong with what he provided post #1. Why he should remove cable from rod to xfmr case and provide SSBJ? I just dont know

No because You dont have EGC to secondary panelboard you have SSBJ different rules sizing.
 
petersonra said:
The GEC bonding jumper from the transformer case to the ground rod is not code required, but it is not prohibited either. My personal opinion is that it needs an EGC (or maybe a SSBJ?) between the transformer case and the panelboard.
Click to expand...
The transformer is on the supply side of the OCPD in the panel, so it would be a supply side bonding jumper.
 
Status
Not open for further replies.
Top