Ground Wire for Feeders

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Alwayslearningelec

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DO most feeders that are feeding distribution panels contain a ground. I know a 3 phase 3 wire is two hots and a neutral and 4 wire is 3 hots and a neutral but what about the ground? I am looking at a feeder that is feeding a 3 phase 3 wire panbel and it only lists 3 wires but i was thinking it would need a ground wire. Thanks.
 
3W three phase feeder could also be 3 hots and no neutral.

Is the conduit metallic, EMT or RMC? That could be your EGC.

All feeders have an EGC, whether it is a conductor or conduit is the question.
 
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jumper said:
Then I would guess the EMT is the EGC and you need to know if this is a 1p or 3p panel being fed by 3W.

You never know what in the mind of some people who write these specs. I would RFI.

What if the 3W feed is a 208V 1P panel with no neutral and a wire EGC is speced?
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Never mind this post above, I reread your OP.

I think you have a straight 3P panel with a EMT as an EGC.
 
Dennis Alwon said:
You cannot have 3 phase with 2 hots and a neutral
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We have to be careful with terminology here. You can have corner grounded 3 phase with 2 hots and a grounded circuit conductor. The equipment grounding conductor is still separate from those three and can be a metal raceway.
 
jumper said:
Then I would guess the EMT is the EGC and you need to know if this is a 1p or 3p panel being fed by 3W.

You never know what in the mind of some people who write these specs. I would RFI.

What if the 3W feed is a 208V 1P panel with no neutral and a wire EGC is speced?
Click to expand...

Thanks...def a 208 3P panel
 
Dennis Alwon said:
You cannot have 3 phase with 2 hots and a neutral
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Dennis so when there is a 3 or 4 wire service or panel how many hots is it being fed with? I thought a 4 wire was 3 hots and a neutral..... or better yet when you have a 3 phase/3 wire panel and the feeder feeding it reads 3 # 3/0 in a 2 1/2" conduit how do you interpret that?
 
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kwired said:
We have to be careful with terminology here. You can have corner grounded 3 phase with 2 hots and a grounded circuit conductor. The equipment grounding conductor is still separate from those three and can be a metal raceway.
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fmtjfw said:
corner grounded delta
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I agree I was careless however I know horsegoer and I was pretty certain he was not talking about a corner grounded delta.
 
jumper said:
But Dennis, you were correct, a corner grounded delta is 3 phases also, there is no neutral, one phase is just grounded.
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I didn't want to get caught up in the semantics of it all. I have never seen a corner grounded system in real life but I would have called it 3 phases obviously others don't see it that way.
 
Dennis Alwon said:
I didn't want to get caught up in the semantics of it all. I have never seen a corner grounded system in real life but I would have called it 3 phases obviously others don't see it that way.
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That is fine, but this is what you said:

You cannot have 3 phase with 2 hots and a neutral
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And it is correct. A corner grounded delta does not have a neutral.

You were not careless IMO.
 
fmtjfw said:
corner grounded delta
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Like I said earlier - be careful with the terminology.

A grounded phase is not a neutral conductor - it is a grounded conductor that normally carries current just like the neutral in a wye or the common tap of a single phase system. It still must be separated into "grounded" and equipment "grounding" conductors beyond the service disconnect just like the neutral in those other systems.
 
kwired said:
We have to be careful with terminology here. You can have corner grounded 3 phase with 2 hots and a grounded circuit conductor. The equipment grounding conductor is still separate from those three and can be a metal raceway.
Click to expand...

Dennis did not say grounded conductor, he said neutral: the grounded phase in a corner grounded delta is not a neutral.
 
horsegoer said:
Dennis so when there is a 3 or 4 wire service or panel how many hots is it being fed with? I thought a 4 wire was 3 hots and a neutral..... or better yet when you have a 3 phase/3 wire panel and the feeder feeding it reads 3 # 3/0 in a 2 1/2" conduit how do you interpret that?
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Even if there is some standard as to how to properly say it, it is not followed consistantly enough throughout the industry.

Example: 120/208 3ph 4 wire - most would assume is 3 phases and a neutral (and it is assumed you always need an equipment ground if on load side of service equipment so there may be a 5th assumed conductor.

Example 208 3 ph 4 wire - most would assume there is no neutral load since the 120 was not mentioned so three phases and an equipment ground.

Example 120/240 3 wire - probably single phase with neutral - equipment ground is needed if on load side of service so 4th wire is assumed.

Example 120/240 3 wire non grounding - kind of the designation for the 3 wire range receptacles where the neutral was allowed to perform equipment grounding also.

You really need to pay attention to other details to hopefully clarify what is needed. If you have a description of loads supplied and there is neutral needed by certain loads you can then figure you need how ever many necessary phases plus the neutral and equipment ground for that load.
 
kwired said:
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Example 208 3 ph 4 wire - most would assume there is no neutral load since the 120 was not mentioned so three phases and an equipment ground.
...
Click to expand...
I would always read that as 3 ungrounded conductors and a grounded conductor.
 
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