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#184736 02/19/09 10:41 PM
Joined: Feb 2006
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I am not sure on how to bond this transformer should the ground from the transformer go to the ground bar in the 100 amp switch or take it down to the trough.

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transformer grounding 1.jpg
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Joined: Feb 2006
Posts: 78
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I am not sure on how to bond this transformer should the ground from the transformer go to the ground bar in the 100 amp switch or take it down to the trough. All conduit is pvc. This building is wood frame with no water pipe, it is just a distribution point. The service 1PH 120/208 coming off the transformer disconnect is aerial to a out building that has water and steel grid for a electrode is 3 wire okay.

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transformer grounding 1.jpg
Joined: Mar 2007
Posts: 404
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Well, first you should spend a lot of quality time with the person(s) in question...

Joined: Feb 2006
Posts: 78
L
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This is a school project that i'am working on and didn't understand your reply.

Joined: Mar 2003
Posts: 849
Y
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Lets see if I understand this ist.
the 200amp is the source of all power right.480/277 Wye Service.
This feeds two 100amp Disconnect switches:
#1 Straight 480V three phase with ground out to external Bld.
#2 to 75kva 480v to 120/208 three phase 4 wire I take it that feeds a 200 amp panel.\
Is there breakers in the 480/277 v panel to the two hundred amp disconnect switches??
Do you have a main on the Load side of the 75KVA panel.
Little more Detail if you can
The 75KVA transformer & Panel After it come Come off 250.30
The Ground there and bonding is either at the transformer OR panel after it but not both (250.30(A)1
The service 120/208 volt single phase coming off the transformer disconnect I'm a little confused there???
Do mean the load side of the 75KVA (thats only 208v in pic.
Prehaps thats a Straight single phase 480Volt 75Kva to 120/240V secondary????
Little more info OK .
Yoopersup



Joined: Feb 2006
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Yoopersup: Fuses in all sswitches,yes there is a fused switch on the secondary side of the transformer which is in the same room, bonding is done in trans, net. and ground are split in the load side sw. The trans. is 480/120/208 three phase my mistake. When the service leaves this building it goes aerial 3 phases and a net. to the next building,where it enters a 200 amp 3 ph panel.

Joined: Apr 2002
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LiteBulb:
May I suggest that you try the following:
Go to the main forum page.
Scroll down to the technical reference box.
Click on that
Look for the transformer setup that you have!

I'm not attempting to blow you away, but trying to make you 'look' thru all the resources here. If you need 'help' that's what most of us are here for, so please check the above area out and let us know if you have it!

Also, your sketch could use a little more info.



John
Joined: Feb 2006
Posts: 78
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John do I have to have a second ground rod at the transformer or can I use the main service ground rod in the trough.
#2 also run a ground from the 100 amp disconnect to the transformer thru the race way.

Joined: Feb 2006
Posts: 78
L
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building #1 is where the main service comes in from power co. that is the drawing the load side fused ssw was cut off in the picture, from there it goes to building #2 which has a 200 amp 120/208 3ph panel in it. Building #3 has a 100 amp 480v 3ph panel.

Joined: Mar 2003
Posts: 849
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Question
Do you have a current NEC code book to Reference answers we give to you reguarding your Questions?? Cause thats a Must.

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