3 PHASE CORNER GROUNDED DELTA
- Thread starter domnic
- Start date
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- Location
- Placerville, CA, USA
- Occupation
- 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.
Add a connection to the local GES and then you have the source for your EGCs.
mivey
Senior Member
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.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
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.
- Location
- New Jersey
- Occupation
- 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
- Occupation
- EC
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.
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.
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 ?
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 ?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Is this the service panel or a sub panel?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
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.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
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.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What do you mean by tap the EGC to? The EGC in the circuit to the water heater can be attached directly to the grounded metal panel enclosure.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
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
- Occupation
- EC
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.
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).
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
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
- Occupation
- EC
A picture of what is there would make it easier for all of us :happyyes:
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