Current Carrying Conductors

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viclibo

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Our city head electrical inspector told me that in 1 phase only the hot is counted as a current carrying conductor when calculaing # of current carrying conductors in a raceway.. In 3 phase both the hot and neutral are counted. Please advise!!!!!!!!!!!!!!!!!!!
 
Hopefully a misunderstanding. In general terms the opposite is true.
Since current flows, anytime you have just two conductors to a load they must both carry that current. On a 3 phase system, with some exceptions, the neutral which carries only unbalanced current is not counted.
See 310.15(B)(4) for further.
 
viclibo said:
Our city head electrical inspector told me that in 1 phase only the hot is counted as a current carrying conductor when calculating # of current carrying conductors in a raceway.. In 3 phase both the hot and neutral are counted. Please advise!!!!!!!!!!!!!!!!!!!
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Sometimes the inspector would be correct and sometimes not.

It depends on the circuit arrangement and the type of load being supplied.
 
viclibo said:
Our city head electrical inspector told me that in 1 phase only the hot is counted as a current carrying conductor when calculaing # of current carrying conductors in a raceway.. In 3 phase both the hot and neutral are counted. Please advise!!!!!!!!!!!!!!!!!!!
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IMO he's misinformed. Since your first sentence you said " 1 phase only the hot is counted as a current carrying conductor" I assume a two wire circuit so he's incorrect. For three phase there are many variables, so as Bob said he would be right or wrong based on the particulars of the installation.
 
viclibo said:
Why can't this be a cut and dry situation. You either can or can't, which is it ?
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Because it is not and it depends.

First off you can choose to always count the neutral as a current carrying conductor. This is code compliant and conservative.

However often it makes a lot of sense not to count the neutral as a current carrying conductor.

For example if I have a 120/240 volt 40 circuit panel with 40 twenty amp circuits from it I have some choices.

I can run 40 two wire (hot and neutral) circuits. In this case the NEC requires the neutral to be considered a current carrying conductor because it carries the same current as the hot. I would have 80 current carrying conductors to deal with.

OR, I could run 20 - twenty amp multi-wire branch circuits (hot, hot, and neutral) circuits in this case the NEC does not require the neutral to be considered a current carrying conductor because it carries only the imbalanced current from the two hots. I would only have 40 current carrying conductors to deal with.

This reduction in current carrying conductors allows us to run smaller or fewer raceways.
 
viclibo said:
Why can't this be a cut and dry situation ? ?
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Because it's in the NEC :)

Actually, few installs are "cut and dry".. different situations call for different rules

viclibo said:
You either can or can't, which is it ?
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Again, DEPENDS... you can in situation A, you can't in situation B

You have to be familiar with 310.15(B)(4) and then determine which condition exists for your particular install, such as is it a linear or non-linear load, is it 3 phase or single phase ?, how many conductors are present ?, etc.
 
viclibo said:
Why can't this be a cut and dry situation. You either can or can't, which is it ?
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You sound like Homer Simpson. ;) If our work was easy, everyone would be doing it.

We're pros because it takes experience and understanding to do our work well and correctly. You come here willing to learn, which is probably the best attribute one can have.

Stick it out and keep on asking questions. That's why we're here. :)
 
LarryFine said:
You sound like Homer Simpson. ;) If our work was easy, everyone would be doing it.

We're pros because it takes experience and understanding to do our work well and correctly. You come here willing to learn, which is probably the best attribute one can have.

Stick it out and keep on asking questions. That's why we're here. :)
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Speak for yourself, I'm here for the money :grin:
 
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