Ground Wire for Feeders

[infinity]

I would always read that as 3 ungrounded conductors and a grounded conductor.

Me too. The EGC is implied and not specific to the 3 phase, 4 wire phrase.

 

[kwired]

I would always read that as 3 ungrounded conductors and a grounded conductor.

OK I might buy that. With plugs and receptacles it will be listed in catalogs as 20 amp 480 volt 3 pole 4 wire for an L16-20 device. This device is not intended to include a neutral. That kind of wording is common for plugs and receptacles, but maybe not for feeders and services.

 

[Strathead]

To get back to Horsegoer's question, there is regretfully no standard as kwired pointed out. I didn't see where anyone told you that usually, wehn talking about feeders, the ground is not included in the wire count. So 3 phase 4 wire is generally 3 hots and a grounded (neutral) conductor. Again, though, no standard. It is like the English language, sometimes you just have to know. Look at cables, an MC, or Romex 3 wire cable is a black, a red, a white and a green or bare conductor. A 3 wire SO cord is a black a white and a green. You just have to know.

 

[Alwayslearningelec]

I agree I was careless however I know horsegoer and I was pretty certain he was not talking about a corner grounded delta.

lol...no I was not.

 

[Alwayslearningelec]

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.

That is helpful....so if you know the load like the example below what woud you say the wire configuration is??

277/480 3P 4W panel feeding a 480V 3P 3W panel and they list the feeder as 3#3/0 in 2 1/2" conduit. Do you think there is a missing conductor? Is it just 3 conductors? Thanks.

Does it help clue you in that it is a feeder feeding a panel????

 

[kwired]

That is helpful....so if you know the load like the example below what woud you say the wire configuration is??

277/480 3P 4W panel feeding a 480V 3P 3W panel and they list the feeder as 3#3/0 in 2 1/2" conduit. Do you think there is a missing conductor? Is it just 3 conductors? Thanks.

Does it help clue you in that it is a feeder feeding a panel????

Does the panel supply any 277 volt loads? That is what I would be looking for to determine if a neutral is needed.

If it only supplies 480 volt loads a neutral is not needed but then you have to decide if you or the designer wants one just in case someday 277 loads will be added.

 

[Alwayslearningelec]

Does the panel supply any 277 volt loads? That is what I would be looking for to determine if a neutral is needed.

If it only supplies 480 volt loads a neutral is not needed but then you have to decide if you or the designer wants one just in case someday 277 loads will be added.

Ok, I'll check but what does the 3W represent..3 hots???? And if it is 3 hots(ungrounded conductors) then you have two questions...the neutral and the EGC....no?

And actually the 277/480 3P 4W panel also feeds a 277/480ZV 3P 4W panel...and still only lists 3 conductors for the feeder??

 

[cdslotz]

Ok, I'll check but what does the 3W represent..3 hots???? And if it is 3 hots(ungrounded conductors) then you have two questions...the neutral and the EGC....no?

And actually the 277/480 3P 4W panel also feeds a 277/480ZV 3P 4W panel...and still only lists 3 conductors for the feeder??

480V, 3Ph, 3W represents 3-hots + EG

277/480V, 3Ph, 4W represents 3-hots, 1-Nuet + EG

If it only lists 3 conductors, to a 277/480V panel, it could be correct or a mistake.
If you are bidding, you could RFI it or give an add below the line for the correction.

 

[Alwayslearningelec]

480V, 3Ph, 3W represents 3-hots + EG

277/480V, 3Ph, 4W represents 3-hots, 1-Nuet + EG

If it only lists 3 conductors, to a 277/480V panel, it could be correct or a mistake.
If you are bidding, you could RFI it or give an add below the line for the correction.

CD thanks but some some thoughts.

1. If it is a 3P 4W panel and only lists 3 conductor is has to me a maistake as the neutral is not indicated correct?
2. The EGC could or could not be required depending if the conduit is being used as the EGC??? THere is not ALWAYS a separate ground wire run??

Thanks again.

 

[Dennis Alwon]

3 wire feeder can be a single phase panel - 2 hots and a neutral- but unlikely. It could also be a straight 3 phase panel where no neutral is needed. I don't see it as a 3 phase panel with neutral.

 

[Alwayslearningelec]

3 wire feeder can be a single phase panel - 2 hots and a neutral- but unlikely. It could also be a straight 3 phase panel where no neutral is needed. I don't see it as a 3 phase panel with neutral.

Got it.....like I said if it is 3P 4W and lists only 3 conductors feeding it then it is obviously missing the neutral and possibly the EGC. Thanks.

 

[cdslotz]

Is this on a set of plans you are bidding?

Are all of the loads in the panel 3Ph/3W? If so, 3 phase conductors will work.
But it may not be the engineer's intent. They may want to pull a neutral for future 277/480V loads.
I see panel schedules all of the time not match the feeder.
Bid as drawn and scheduled and qualify it.

 

[jim dungar]

... 277/480 3P 4W panel also feeds a 277/480ZV 3P 4W panel...?

The correct terminology, per ANSI/IEEE standards, and referenced in the NEC is: 480Y/277V [3Ph 4W is optional] for 3 lines + 1 neutral, ground is not mentioned. but, for some reason many utilites and manufacturers do not follow this terminology.

In my experience grounding conductors are not included in the vast majority of descriptions; the two notable exceptions being cables and wiring devices.

 

[kwired]

The correct terminology, per ANSI/IEEE standards, and referenced in the NEC is: 480Y/277V [3Ph 4W is optional] for 3 lines + 1 neutral, ground is not mentioned. but, for some reason many utilites and manufacturers do not follow this terminology.

In my experience grounding conductors are not included in the vast majority of descriptions; the two notable exceptions being cables and wiring devices.

Utilities don't mention EGC because they are rarely dealing with EGC's as they are typically only talking service conductors.

 

[Alwayslearningelec]

Is this on a set of plans you are bidding?

Are all of the loads in the panel 3Ph/3W? If so, 3 phase conductors will work.
But it may not be the engineer's intent. They may want to pull a neutral for future 277/480V loads.
I see panel schedules all of the time not match the feeder.
Bid as drawn and scheduled and qualify it.

It's a budget...but also want to know about thbis for my own knowledge. I can you tell if all the loads out of the panel that is being fed are 3P3W? What is some are single phase?

 

[Alwayslearningelec]

Utilities don't mention EGC because they are rarely dealing with EGC's as they are typically only talking service conductors.

I have seen many feeder schedules list the ground wire.

 

[cdslotz]

It's a budget...but also want to know about thbis for my own knowledge. I can you tell if all the loads out of the panel that is being fed are 3P3W? What is some are single phase?

Are you typing with your feet?
Please translate

 

[cdslotz]

BTW, I have not seen a single spec in many years that don't require a full EG wire. It doesn't matter if it's not on the schedule or one-line.
I would NEVER design or install a job without a full EG wire.

 

[Little Bill]

Utilities don't mention EGC because they are rarely dealing with EGC's as they are typically only talking service conductors.

I have seen many feeder schedules list the ground wire.

Utilities will never be talking about feeders. They are only concerned about service conductors. You need to realize what you are looking at. If it is a feeder, it will need an EGC, whether a wire or conduit.
Kwire was talking about SEC and your example is for feeders, thus the ground wire being listed.

 

[kwired]

I have seen many feeder schedules list the ground wire.

Yes to what Little Bill said. Utilities are not talking feeders they are talking service conductors. Equipment ground and grounded service conductor are essentially same conductor in those cases. Separate conductors is pointless if they are connected together at each end as this makes them parallel and not separate in function.