Phase wires

[Alwayslearningelec]

Ok, I know this may be one of my real dumb questions.

I am use to seeing where they indicate (3) hots & (1) ground...say (3)#4's and (1) #8 but I have come across(just seen it..not for me to take-off) where they show only (4) conductors of the same size. Say (4) #250's 4/0's etc. What does this indicate and why???? (4) HOTS??? can't be (4) phases, right??? A nuetral or ground the same size??? Thanks alot

 

[infinity]

Say (4) #250's 4/0's etc. What does this indicate and why???? (4) HOTS??? can't be (4) phases, right??? A nuetral or ground the same size??? Thanks alot

My guess is that they're calling for the metallic raceway to be used as the EGC.

 

[roger]

Are these service entrance conductors?

Roger

 

[sameguy]

Wait till you only see hash marks.

 

[Rockyd]

See 220.61, 250.24 (C) & (D), 250.118, and 250.122(A) & (B). Hoping you have a NEC Handbook? If not, invest in one for yourself for a lot of explanatory material. I buy one every other code cycle normally.

Edit - 250.30(A)(3) too...

 

[Smart $]

... A nuetral or ground the same size??? ...

It's not uncommon for a neutral conductor of a 3? 4W wye service or feeder to be the same size as the line conductors. It actually has to be if all the loads are line to neutral.

 

[cdslotz]

I'm looking at a feeder schedule now, so a typical 3ph, 4w feeder reads (example):
for a 300A feeder = 4-350KCMIL, #4G in 3 1/2"C

3-350(hot), 1-350(nuet), 1-#4(eg)

 

[Alwayslearningelec]

I'm looking at a feeder schedule now, so a typical 3ph, 4w feeder reads (example):
for a 300A feeder = 4-350KCMIL, #4G in 3 1/2"C

3-350(hot), 1-350(nuet), 1-#4(eg)

So sometimes the EG is not needed?

 

[Smart $]

So sometimes the EG is not needed?

Sometimes the conduit is the EGC, so there would be no EGC wire spec'd for the run.

 

[roger]

So sometimes the EG is not needed?

If it is a feeder or branch circuit it is required, it may not neccessarily be a wire though.

In Cslotz post EG's are listed in the schedule.

Roger

 

[Rockyd]

It's not uncommon for a neutral conductor of a 3? 4W wye service or feeder to be the same size as the line conductors. It actually has to be if all the loads are line to neutral.

Depends on the maximum unbalanced load (220.61), or if it is a Delta service 250.24(C) & (D) Largest of the choices.

 

[Strife]

It can mean either:
1: A system where the conduit is the grounding conductor. (IE 3ph+1 grounded conductor + EMT)
2: A service entrance system where a grounding conductor is not installed.
Taken a little extreme it can also mean:
3: 3PH+same size grounding conductor and no grounded conductor, but that's pretty much bad engineering. The grounding conductor should always be specified separately even if it's same size.

Ok, I know this may be one of my real dumb questions.

I am use to seeing where they indicate (3) hots & (1) ground...say (3)#4's and (1) #8 but I have come across(just seen it..not for me to take-off) where they show only (4) conductors of the same size. Say (4) #250's 4/0's etc. What does this indicate and why???? (4) HOTS??? can't be (4) phases, right??? A nuetral or ground the same size??? Thanks alot

 

[Smart $]

Depends on the maximum unbalanced load (220.61), or if it is a Delta service 250.24(C) & (D) Largest of the choices.

As I said, if all the loads are line to neutral, the maximum unbalanced load on the neutral is equal to the calculated load on any one line conductor, necessitating the neutral to be the same size. An example is a lighting panel with only 120 or 277 volt lighting loads.

...And I specifically said a wye supply.

 

[Smart $]

... The grounding conductor should always be specified separately even if it's same size.

I disagree. Only specify separately when not the same size... :happyyes: