# Transformer connection



## MDShunk (Jan 7, 2007)

Sure, if it doesn't have one. Maybe I'm not getting your question completely.


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## Salvatoreg02 (Feb 26, 2011)

MDShunk said:


> Sure, if it doesn't have one. Maybe I'm not getting your question completely.


 Do you install all your EGC's and neutral under one lug attached to XO. OR DO YOU separate your EGC's w/ sepetste lug an attach to frame


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## jmsmith (Sep 10, 2011)

Salvatoreg02 said:


> Do you install all your EGC's and neutral under one lug attached to XO. OR DO YOU separate your EGC's w/ sepetste lug an attach to frame


Most I have seen should already have a bonding strap attaching the core to the case. I would attach your EGC at this point, and a bonding jumper from this point to X0. That is just the way I was taught-neutral and this bond on X0 only. Hope this makes sense.


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## Pete m. (Nov 19, 2011)

AFAIK, unless a lug is specifically listed for more than one conductor a separate one would be required for each.

Pete


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## Selectric (Aug 18, 2009)

I always take my equipment grounds to the bottom of the case. Then take my bond from building steel through a lay-in lug on the case to XO.


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## Salvatoreg02 (Feb 26, 2011)

So would you guys say it's acceptable to land your Neutral and EGC's and GEC to XO??

Transformer has a main bonding jumper installed by manufacture. 

Obviously a EGC from the 480panel and EGC from secondary side to panel


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## tates1882 (Sep 3, 2010)

Salvatoreg02 said:


> So would you guys say it's acceptable to land your Neutral and EGC's and GEC to XO??
> 
> Transformer has a main bonding jumper installed by manufacture.
> 
> Obviously a EGC from the 480panel and EGC from secondary side to panel


Really if you check in the NEC you are not required to have an EGC on the secondary side. The primary EGC land on the case then the secondary consists of phases and grounded conductor. GEC for secondary side goes to the main of the SDS with bonding jumper at the main. 

With your way you have a parallel path for the neutral.


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## brian john (Mar 11, 2007)

tates1882 said:


> Really if you check in the NEC you are not required to have an EGC on the secondary side. The primary EGC land on the case then the secondary consists of phases and grounded conductor. GEC for secondary side goes to the main of the SDS with bonding jumper at the main.
> 
> With your way you have a parallel path for the neutral.


Not if he only does his bonding in the transformer. You do not need to do it in the panel. Primarily around here close to 100% are bonded in the transformer.


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## don_resqcapt19 (Jul 18, 2010)

tates1882 said:


> Really if you check in the NEC you are not required to have an EGC on the secondary side. The primary EGC land on the case then the secondary consists of phases and grounded conductor. GEC for secondary side goes to the main of the SDS with bonding jumper at the main.
> 
> With your way you have a parallel path for the neutral.


You have to have a supply side bonding jumper between the first OCPD and the transformer, no matter where you installed the neutral bond.


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## piperunner (Aug 22, 2009)

Well on the secondary side of the transformer the last few jobs all grounding conductors are to be one common lug for grounds no separate lugs in addition the bond from building steel or cold water included on this ground bar. 
We run the full size jumper even if the factory bonding strap is already installed and no cut jumper it is run uncut to neutral on secondary side of trans and a pass thur or J lug is used to help this make it easy which hits the frame first before the neutral . Its in our spec


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## erics37 (May 7, 2009)

I installed a 45 kVA Eaton transformer a month or three ago and its X0 was a bar with maybe 5 holes pre-drilled in it, and a bonding jumper factory installed to the frame. It made everything really easy; just wired all my crap directly to the X0 bar.


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## Salvatoreg02 (Feb 26, 2011)

So my question really is, if I land my neutral, EGC from both primary feed and secondary and building steel, I can technically land everything under one multi-tap mechanical lug and land on XO in Transformer??


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## erics37 (May 7, 2009)

Salvatoreg02 said:


> So my question really is, if I land my neutral, EGC from both primary feed and secondary and building steel, I can technically land everything under one multi-tap mechanical lug and land on XO in Transformer??


Yes.

Your transformer secondary is a separately derived system, therefore it needs a system bonding jumper which can be installed anywhere between the transformer and the first means of disconnect; the only caveat is that where the bonding jumper is, the GEC (in your case, building steel) needs to land in the same place.

Quite often, the easiest place to do all that is X0.


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## BBQ (Nov 16, 2010)

Salvatoreg02 said:


> So my question really is, if I land my neutral, EGC from both primary feed and secondary and building steel, I can technically land everything under one multi-tap mechanical lug and land on XO in Transformer??


Still need a jumper to the transformer case


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## Salvatoreg02 (Feb 26, 2011)

Great pic..
How come the illustration doesn't don't show the EGC from the primary side. I know it's a silly question, is their reasoning behind that??


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## Salvatoreg02 (Feb 26, 2011)

BBQ said:


> Still need a jumper to the transformer case


The manufacture has already installed one. Do I still need an additional jumper from XO to the chassis of frame.


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## Salvatoreg02 (Feb 26, 2011)

I'll post a pic shortly.


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## BBQ (Nov 16, 2010)

Salvatoreg02 said:


> The manufacture has already installed one. .


I doubt that, normally that just is just a jumper across the isolation mounts. 

The EGC of the primary must be connected to the enclosure just like the EGC of any feeder has to connected to the enclsure.


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## Salvatoreg02 (Feb 26, 2011)

BBQ said:


> I doubt that, normally that just is just a jumper across the isolation mounts.
> 
> The EGC of the primary must be connected to the enclosure just like the EGC of any feeder has to connected to the enclsure.


I'm looking at it now I see that. I did install one bonding bushing from the 480 feeder and install a Lay-in lug for my EGC. Does this qualify??


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## BBQ (Nov 16, 2010)

For a minute forget it is a transformer, think of it as a piece of equipment that runs on 480 volts, let's say it is a machine. 

How would you ground the machines enclsure?


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## Salvatoreg02 (Feb 26, 2011)

BBQ said:


> Still need a jumper to the transformer case


What about the emt conduit doesn't that bond the transformer case


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## BBQ (Nov 16, 2010)

Salvatoreg02 said:


> What about the emt conduit doesn't that bond the transformer case


If you were supplying any load in a metal enclsure with a circuit that includes a wire EGC would you just land that EGC on a bonding bushing but not onto the enclosure?


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## Salvatoreg02 (Feb 26, 2011)

BBQ said:


> If you were supplying any load in a metal enclsure with a circuit that includes a wire EGC would you just land that EGC on a bonding bushing but not onto the enclosure?


I got that part about the EGC. But, does the emt conduit qualify as a bonding means for the transformer case??


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## Salvatoreg02 (Feb 26, 2011)

It's funny but while I'm commucatibngv here their is a state inspector checking out our job. He's already found 4 transformers that were bonded at both ends.


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## Salvatoreg02 (Feb 26, 2011)

Completed


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## Salvatoreg02 (Feb 26, 2011)

Thanks everyone who contributed too this conversation. There were many discrepancies at work regarding grounding transformers. We eventually got it right.


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