SDS 480Y to 208 Y Transformer Grounding

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Saturn_Europa

Saturn_Europa

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Fishing Industry
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Electrician Limited License NC, QMED Electrician
I have a 35 Kw, NEMA 3R, 480 Y to 208 Y transformer at my plant. X0 has a bonding jumper attached to the ground lug on the case of the transformer, the grounding electrode conductor is also attached to a ground lug on the case of the transformer then to some building steel. Five feet from the transformer is the 208 panel board. It has a system bonding jumper connected to the neutral bus bar. There is also a EGC from the panel board to the case of the transformer.

My question is: Doesnt this set up a parallel path to the source? Should I lift the system bonding jumper at the panel board?
 
Saturn_Europa said:
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My question is: Doesnt this set up a parallel path to the source? Should I lift the system bonding jumper at the panel board?
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Yes, it establishes a parallel path... and yes, remove the N-G jumper in the panelboard. The N-G jumper must be in the same enclosure as the GEC connection.
 
Saturn_Europa said:
I have a 35 Kw, NEMA 3R, 480 Y to 208 Y transformer at my plant. X0 has a bonding jumper attached to the ground lug on the case of the transformer, the grounding electrode conductor is also attached to a ground lug on the case of the transformer then to some building steel. Five feet from the transformer is the 208 panel board. It has a system bonding jumper connected to the neutral bus bar. There is also a EGC from the panel board to the case of the transformer.

My question is: Doesnt this set up a parallel path to the source? Should I lift the system bonding jumper at the panel board?
Click to expand...

Yes it does.

Yes. Remove any EGs from the neutral bus bar and give them their own bar bonded to the can. I think you have it figured out already.
 
Saturn_Europa said:
I have a 35 Kw, NEMA 3R, 480 Y to 208 Y transformer at my plant. X0 has a bonding jumper attached to the ground lug on the case of the transformer, the grounding electrode conductor is also attached to a ground lug on the case of the transformer then to some building steel. Five feet from the transformer is the 208 panel board. It has a system bonding jumper connected to the neutral bus bar. There is also a EGC from the panel board to the case of the transformer.
Click to expand...


This would actually be considered a SSBJ (supply side bonding jumper) not an EGC, there is a distinction between to the two because sizing them is different.

As others have stated you'll need to remove the jumper in the panel because the neutral current is now flowing on the SSBJ and any metal between the panel and the transformer including metallic raceways if used.
 
dionysius said:
Beautiful pics Augie. Are we allowed to know what tool you are using to create such fine drawings???
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Those are oil paintings on canvas that Gus creates. After that he just takes a picture of them and posts them here.

He sells signed originals on the side.
 
dionysius said:
Beautiful pics Augie. Are we allowed to know what tool you are using to create such fine drawings???
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I recommend you disregard the two previous posts. I apologize on their behalf. They could not contain the wise cracker side of their personalities. :lol:
 
dionysius said:
Beautiful pics Augie. Are we allowed to know what tool you are using to create such fine drawings???
Click to expand...

Mike Holt has hundreds of those graphics in pdf form that you can view for free on the Internet. Just type a code section into Google and click on the images tab in the search results. At one time they were not all pdf's but actually images which allowed you to easily insert them into a post. For some reason the newer ones are now pdf's.
 
infinity said:
Mike Holt has hundreds of those graphics in pdf form that you can view for free on the Internet. Just type a code section into Google and click on the images tab in the search results. At one time they were not all pdf's but actually images which allowed you to easily insert them into a post. For some reason the newer ones are now pdf's.
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Hmmm.... not sure where you are getting the pdf's. Google's image tab does not display pdf's.
 
dionysius said:
Beautiful pics Augie. Are we allowed to know what tool you are using to create such fine drawings???
Click to expand...

You may not know but that image is one of Mike Holt's. I do not know who the graphic artist is, or if it is Mike himself.

Using Google image search as Rob mentioned is a good way to find them. Another great place to go is the Mike Holt free resources page.


Check it out, lots of great stuff there. Mike Holt Free Resources
 
iwire said:
You may not know but that image is one of Mike Holt's. I do not know who the graphic artist is, or if it is Mike himself.

Using Google image search as Rob mentioned is a good way to find them. Another great place to go is the Mike Holt free resources page.


Check it out, lots of great stuff there. Mike Holt Free Resources
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That is the origin of the pic i posted.
 
Smart $ said:
Hmmm.... not sure where you are getting the pdf's. Google's image tab does not display pdf's.
Click to expand...

There was a time when the image was simply a thumbnail and when you went to copy it the only option was a pdf. I see now that's been changed and they're available as .png files which is helpful when adding them to a post.
 
Is the conduit used between the Main and the xmfr sufficient for the egc or is a separate conductor required?
 
I think one reason the MH graphics have disappeared from the free stuff section is people were posting them all over the internet and using them with out Mike Holt's permission.

Roger
 
iwire said:
You may not know but that image is one of Mike Holt's. I do not know who the graphic artist is, or if it is Mike himself.

Using Google image search as Rob mentioned is a good way to find them. Another great place to go is the Mike Holt free resources page.


Check it out, lots of great stuff there. Mike Holt Free Resources
Click to expand...
Mike Culbreath does all of the graphics for Mike Holt. He is an electrician, but I believe that he works full time for Mike Holt now.
 
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