3 PHASE CORNER GROUNDED DELTA

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domnic

Senior Member
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Electrical Contractor
Looked at a job today to run wiring to new water heater. the panel was 200 amp 3 phase corner grounded delta #3/0 wire from meter base to 3 pole 200 amp breaker in panel no EGC in panel how do i get a EGC?
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
From the primary grounded conductor, even though it is not a neutral. Just as you would with a three phase four wire service.
Add a connection to the local GES and then you have the source for your EGCs.
 

mivey

Senior Member
Looked at a job today to run wiring to new water heater. the panel was 200 amp 3 phase corner grounded delta #3/0 wire from meter base to 3 pole 200 amp breaker in panel no EGC in panel how do i get a EGC?
Picture a single-phase service. Now substitute the two line conductors for the two ungrounded corners and the neutral for the grounded corner. Now where would you get the EGC?

From the grounded corner, of course, which is our re-pictured "neutral". A "neutral" is a grounded conductor as well.
 

GoldDigger

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The other consideration is that your EGC has to originate at or near the service panel, not a sub panel. At a sub panel the raceway may be providing the EGC for you.
 

infinity

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Location
New Jersey
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Journeyman Electrician
If the system were grounded within the the panel and the panel enclosure is metallic that would be one place where you could connect your EGC(s).
 

kwired

Electron manager
Location
NE Nebraska
Do not equate neutral, ground, grounded, grounding. They are often confused because people all think of them as the same thing. Sometimes some of them are the same thing, and other specific instances they have definite different meanings.

NEC uses the term "grounded" conductor "equipment grounding" conductor in many places for a reason - to specify just what the function of that conductor is though electrically they both are similar - there is a difference. NEC doesn't use the term "neutral" all that often, but when it does - it is referring to the conductor it gave a specific definition for. Neutral conductors are usually also grounded conductors - but there are instances where they are not grounded.
 

domnic

Senior Member
Occupation
Electrical Contractor
Corner grounded delta

Corner grounded delta

I understand how a corner grounded works . what i want to know is where to connect the EGC to .the wires to the panel are in 2" rmc with no grounded bushing and go to a 3 phase breaker . where do i tap the EGC to ?
 

GoldDigger

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Location
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I understand how a corner grounded works . what i want to know is where to connect the EGC to .the wires to the panel are in 2" rmc with no grounded bushing and go to a 3 phase breaker . where do i tap the EGC to ?
Is this the service panel or a sub panel?
 

domnic

Senior Member
Occupation
Electrical Contractor
Corner grounded delta

Corner grounded delta

It is a 200 amp service.
 

infinity

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New Jersey
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One way to do it is to attach a lug to the metallic panel enclosure or since this is a service go right to the "neutral" bar.
 

GoldDigger

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It is a 200 amp service.
In that case the installation may never have been complete according to code. The grounded incoming conductor and a ground electrode conductor from somewhere need to be connected and bonded to the enclosure (unless that bonding was done upstream in the meter enclosure?)
You will then have a main grounding point from which the separate neutrals (which you do not have any of....) and EGCs originate.
A three phase grounded delta can use the neutral/ground bar in the enclosure as the connection point for the feeder and branch grounded conductors and EGCs.
If the panel has three phase buses, then one of them will normally not be used for grounded delta, although using two and three pole breakers which also switch the grounded conductor for each circuit is permissible as an option.
 

domnic

Senior Member
Occupation
Electrical Contractor
Corner grounded delta

Corner grounded delta

I agree with with all replies. BUT WHERE DO I TAP EGC TO?
 

domnic

Senior Member
Occupation
Electrical Contractor
Corner grounded delta

Corner grounded delta

I meant bonding jumper .
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
One way to do it is to attach a lug to the metallic panel enclosure or since this is a service go right to the "neutral" bar.

I often wonder what people are thinking when they ask a question like this. I am convinced that someone must have told them a long time ago that there had to be a ground bar that they attach the EGC to. It just never seems to occur to them that the ground bar is just screwed to the sheet metal of the PB. No reason you can't bolt a lug to that same sheet metal for an EGC connection. Those same people will never think twice about using a double lock nut as an EGC connection but bolting a lug to the same piece of sheet metal escapes them somehow.
 

kwired

Electron manager
Location
NE Nebraska
I agree with with all replies. BUT WHERE DO I TAP EGC TO?

I meant bonding jumper .

Not sure you are on same page as other people that have replied.

A properly installed service will have the grounded service conductor bonded to the service equipment enclosure already. If you need a place to land an additional EGC and there is no EGC lug or bus bar to land it in, then you can attach a lug or bus bar to the enclosure - likely need to remove paint so you have better insurance of continuity. If you have a metal raceway leaving that service enclosure it can serve as an EGC and standard locknuts are an effective way of bonding it - but watch for complications if over 250 volts to ground and using concentric/eccentric knockouts.
 

Smart $

Esteemed Member
Location
Ohio
I meant bonding jumper .

Not sure you are on same page as other people that have replied.

A properly installed service will have the grounded service conductor bonded to the service equipment enclosure already. ...
I believe he's saying there is no main bonding jumper.

Amounts to, he will have to install one to make his installation compliant, regardless of it not being compliant previously. He'll have to "tap" the grounded supply conductor and connect the other end to a grounding terminal bus (or use any other approved means).
 

GoldDigger

Moderator
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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I believe he's saying there is no main bonding jumper.

Amounts to, he will have to install one to make his installation compliant, regardless of it not being compliant previously. He'll have to "tap" the grounded supply conductor and connect the other end to a grounding terminal bus (or use any other approved means).

And just to make it 100% clear, that is the grounded *supply* conductor from the line side of the three pole breaker, not the load side!
 

kwired

Electron manager
Location
NE Nebraska
I believe he's saying there is no main bonding jumper.

Amounts to, he will have to install one to make his installation compliant, regardless of it not being compliant previously. He'll have to "tap" the grounded supply conductor and connect the other end to a grounding terminal bus (or use any other approved means).

A picture of what is there would make it easier for all of us :happyyes:
 
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