I hope I can make this simple enough. I have a primary disconect for a transformer. Whoes equipment ground comes from a central grounding point which is a copper buss. The ground goes to the disconect and then down to the transformer. I bond my neutral in this transformer. Now the grounding conductor I run to building steel I want to run back to this copper buss! As building steel is not really accessable and every thing is run back to this buss. Is this legal? I Basically have two conductors that go exactly to the same place and it is confussing me. Can you help shed a little light on my subject? Thanks
Transformer grounding
- Thread starter arnettda
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Jim W in Tampa
Senior Member
- Location
- Tampa Florida
You can have more than one grounding conductor. Just be sure you do not parallel the grounded neutral
Karl H
Senior Member
- Location
- San Diego,CA
Here's a tip. A lot of people get confused when it comes to "grounding/bonding" transformers. The number one reason I have found
that very smart people get confused by "Grounding/Bonding" transformers
is the lack of "Basic Electrical" Theory. If you spend some time,patience, and
persistence it will all become clear, as it did for me. Good luck to you.
that very smart people get confused by "Grounding/Bonding" transformers
is the lack of "Basic Electrical" Theory. If you spend some time,patience, and
persistence it will all become clear, as it did for me. Good luck to you.
What is your wiring method that the equipment ground is not with the feeder conductors to the transformer disconnect.
My primary of the transformer is straight three phase. My secondary derives the neutral. does this make a differece.
The feeder conductors come from a panel where the is no actual equipment ground conductor. All the old piping is rigid metal conduit.
My two seperate grounds would go the the frame of the transformer. And I would only have one wire that would go from frame to the neutral lug of transformer?
Is this different than bringing all wires to the big neutral bar of transformer and then bringing one wire down to bond the frame of transformer?
Please clarify for me. When you say you have "two conductors going to the same buss" are you speaking of the neutral and ground from the secondary side of your transformer ? And did you bond "XO" in the transformer ?
It sounds like someone took a short cut with the primary equipment ground conductor.That should have been installed with the primary feeder conductors.
Two ways to do grounding in the transformer. Both primary and secondary ground go to the frame along with the system bonding jumper to the XO. The grounding electrode conductor can go to the xo or with the primary and secondary grounds. So you would need either a 3 hole lug at the XO and at the transformer grounds or you would need a 2 hole lug at the XO and a 4 hole lug at the frame.
Rick
Two ways to do grounding in the transformer. Both primary and secondary ground go to the frame along with the system bonding jumper to the XO. The grounding electrode conductor can go to the xo or with the primary and secondary grounds. So you would need either a 3 hole lug at the XO and at the transformer grounds or you would need a 2 hole lug at the XO and a 4 hole lug at the frame.
Rick
[QUOTE=augie47;1138821]Please clarify for me. When you say you have "two conductors going to the same buss" are you speaking of the neutral and ground from the secondary side of your transformer ? And did you bond "XO" in the transformer ?[/QUOTE]
I bonded XO in the transformer. My two conductors would be the one that grounds the primary disonect and then goes down to the trans. And the second one would be the one from the trans. to building steel but instead of steel i am going back to the same grounding bus.
I bonded XO in the transformer. My two conductors would be the one that grounds the primary disonect and then goes down to the trans. And the second one would be the one from the trans. to building steel but instead of steel i am going back to the same grounding bus.
david
Senior Member
- Location
- Pennsylvania
The primary feeder equipment ground is not the same as the secondary system grounding electrode conductor. First decide where the load side of the point of grounding of a separately derived system is. You decided the point of grounding/ bonding to be at the transformer when you bonded the neutral at the transformer.
Now you need a main bonding from the Transformers derived neutral to the secondary systems equipment grounding most likely an equipment ground bar in the secondary conductors disconnect
Also you need a grounding electrode conductor from the secondary nuetral to the closes grounding electrode you can connect to in the area of your transformer
You also need a main bonding from the secondary derived nuetral to the building steel and a main bonding to the metal water system
david
Senior Member
- Location
- Pennsylvania
He never mention that the secondary system originated in the structure in listed service equipment
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