CCC or Not?

[A/A Fuel GTX]

Would the grounded conductor in a 4 wire range circuit be considered a CCC?

 

[augie47]

Depends on what type system it's fed from. Omn a 240/120 single-phase, it is not a CCC. On a 3 phase system it would be.

 

[A/A Fuel GTX]

That really confuses me.........

 

[steve66]

Depends on what type system it's fed from. Omn a 240/120 single-phase, it is not a CCC. On a 3 phase system it would be.

I have to disagree. I would say no for both cases - 310.15(B)(4)(a) for single phase, and (b) for 3 phase.

Steve

 

[curt swartz]

Steve, 310.15(B)(4)b says it must be counted as a current carrying conductor.

 

[raider1]

Steve, 310.15(B)(4)b says it must be counted as a current carrying conductor.

I agree, if this range circuit was on a 3 phase system you would need to count the neutral.

Chris

 

[dcspector]

I agree, if this range circuit was on a 3 phase system you would need to count the neutral.

Chris

What is the intent? Is it due to the fact it is carrying unbalance from multiple phases?

 

[steve66]

Steve, 310.15(B)(4)b says it must be counted as a current carrying conductor.

You are right, I didn't read that paragraph carefully enough. The neutral does count under 310.15(B)(4)b.

But if we go back to the original post, we had a "4 wire range". Doesn't that imply a 3 phase system? And if it is 3 phase, that means the neutral is not a CCC per 310.15(B)(4)a.

Steve

 

[steve66]

After a little more thought, maybe I didn't understand what was meant by "4 wire". Now I think I do.

4 wire means (2) hot wires, a neutral, and a ground. Is that right?? Now Augie and Raider's comments make sense.

I was thinking about 3 hot wires, and a neutral.

Steve

 

[raider1]

What is the intent? Is it due to the fact it is carrying unbalance from multiple phases?

If the neutral is only carrying the imbalance from 2 of the 3 phases of a 3 phase system, then the neutral will carry almost the same current as the ungrounded conductors, therefore you must count it as a current carrying conductor.

Chris

 

[raider1]

After a little more thought, maybe I didn't understand what was meant by "4 wire". Now I think I do.

4 wire means (2) hot wires, a neutral, and a ground. Is that right?? Now Augie and Raider's comments make sense.

I was thinking about 3 hot wires, and a neutral.

Steve

That is what I understood when the original poster said "4 wire range" 2 hots, 1 neutral and 1 EGC. I always think of a 3 wire range as a range that uses the neutral for bonding purposes.

Chris

 

[A/A Fuel GTX]

Yes, my intent was to reference a typical residential range circuit consisting of 2 phase conductors, 1 grounded conductor and 1 grounding conductor. I still have a hard time rationalizing the three phase scenario where the grounded conductor would be counted as a CCC. You still have a single phase load with 2 phase conductors and 1 grounded conductor.

 

[raider1]

You still have a single phase load with 2 phase conductors and 1 grounded conductor.

But when you are dealing with a 3 phase system, the neutral conductor is connected to the common point of 3 ungrounded conductors. The only time the neutral will not count as a CCC on a 3 phase system is when it is carrying the unbalanced between all 3 phase conductors. If the neutral is carrying only the imbalanced current from 2 of the 3 phases the current on the neutral will be very close to that of the highest ungrounded conductor.

Here is the formula for finding neutral current for a 3 phase system.

As you can see if Phase a was 10 amps and Phase b was 12 and Phase c 0 then the neutral would carry 11 amps.

Chris

 

[infinity]

If the neutral is only carrying the imbalance from 2 of the 3 phases of a 3 phase system, then the neutral will carry almost the same current as the ungrounded conductors, therefore you must count it as a current carrying conductor.

Chris

Yes, my intent was to reference a typical residential range circuit consisting of 2 phase conductors, 1 grounded conductor and 1 grounding conductor. I still have a hard time rationalizing the three phase scenario where the grounded conductor would be counted as a CCC. You still have a single phase load with 2 phase conductors and 1 grounded conductor.

You have to be careful when you use the term 3 phase system. The system that Chris is talking about is a 3 phase Wye system where the neutral would be a CCC. In a 3 phase, 4 wire Delta system the neutral would not be a CCC.

 

[raider1]

You have to be careful when you use the term 3 phase system. The system that Chris is talking about is a 3 phase Wye system where the neutral would be a CCC. In a 3 phase, 4 wire Delta system the neutral would not be a CCC.

Good point, I am talking about a 3 phase Wye connected system. The answer I gave was in regards to 310.15(B)(4)(b) which is talking about a 4 wire, 3 phase Wye connected system.

Chris

 

[infinity]

Good point, I am talking about a 3 phase Wye connected system. The answer I gave was in regards to 310.15(B)(4)(b) which is talking about a 4 wire, 3 phase Wye connected system.

Chris

I knew that's what you meant.

 

[A/A Fuel GTX]

So to play it safe, when in doubt, count the neutral as a CCC.....

 

[infinity]

So to play it safe, when in doubt, count the neutral as a CCC.....

You could do that as long as it doesn't adversely impact your installation. The real concern is when using a single phase, 4 wire circuit from a WYE system. For everyday 120/240 volt systems you won't need to concern yourself about the neutral being a CCC.