counted as current carrying

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normbac

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would you have to count travelers of a 3way switch as two current carrying conductors since only one would carry current at a time. :confused:
 
I agree with Bob however I don't think there is any article that will support this either. I think of it as common sense. :)
 
normbac said:
but why as far as derating ccc in a conduit due to heat
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There is no reason and we don't even need to use the now deceased "Common Sense", electrical theory and physics will support only counting one as a CCC.

FWIW, I agree with both points of Bob's post. :grin:

Roger
 
normbac said:
for purposes of box fill I agree but why as far as derating ccc in a conduit due to heat
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I agree only to add pipe fill as well but still only one ccc there is no way both travelers can carry current at the same time. Unless of course there is a switch malfunction or a short between the two travelers which would result in the lights staying on regardless of switch position resulting in servicing the switching system. This is worse case scenario.
 
I agree with Bobs logic but fact is NEC did not make an exception. Stupid as it is we must count it as 2. NEC says nothing about how often it is used. It is there to do what ? Carry current is its intent and it will. Not saying i think its right.
 
If you have two loads installed in a raceway that will not operate at the same time do you need to count all of the conductors as CCC, I never do.

One possible situation would be heating and cooling circuits installed in same raceway or maybe a normal process load vs a cleanup load where the two loads would never run simultaneously.
 
kwired said:
If you have two loads installed in a raceway that will not operate at the same time do you need to count all of the conductors as CCC, I never do.

One possible situation would be heating and cooling circuits installed in same raceway or maybe a normal process load vs a cleanup load where the two loads would never run simultaneously.
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Code referance that permits this ?
 
normbac said:
would you have to count travelers of a 3way switch as two current carrying conductors since only one would carry current at a time. :confused:
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I just registered a year ago. I can't believe this question hasn't been asked before?
Is there an appointed historian for this forum?
iwire said:
I say no but predict this will be a long thread. :grin:
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Agree and agree.
 
I can't find one that permits it, but also can't find one that prohibits this either. Am suggesting that it is a similar situation to the OP. IMO if a conductor is not going to carry current at the same time as another conductor then the heat produced within a raceway would be the same as if the non carrying conductor were not there which is the intent of the deration to begin with. I can see some arguement to this but if there would be some type of interlock to keep both loads from operating at the same time then why not? A similar situation exists for feeder and service calculations as well as neutrals carrying unbalanced current. The real question is what are current carrying conductors for this particular situation?
 
kwired said:
I can't find one that permits it, but also can't find one that prohibits this either. Am suggesting that it is a similar situation to the OP. IMO if a conductor is not going to carry current at the same time as another conductor then the heat produced within a raceway would be the same as if the non carrying conductor were not there which is the intent of the deration to begin with. I can see some arguement to this but if there would be some type of interlock to keep both loads from operating at the same time then why not? A similar situation exists for feeder and service calculations as well as neutrals carrying unbalanced current. The real question is what are current carrying conductors for this particular situation?
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Hard to argue with this statement A similar situation exists for feeder and service calculations as well as neutrals carrying unbalanced current.
 
Well, then you should count none of the conductors, because no conductor always carries current. Maybe nothing is plugged-in to the receptacle, maybe the breaker is off, maybe the main is disconnected, maybe the meter is unscrewed...
 
Jim W in Tampa said:
I agree with Bobs logic but fact is NEC did not make an exception. Stupid as it is we must count it as 2. NEC says nothing about how often it is used. It is there to do what ? Carry current is its intent and it will. Not saying i think its right.
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Jim W in Tampa said:
Code referance that permits this ?
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Jim, the CMP disagrees with you.


6-50 Log #1405 NEC-P06 Final Action: Reject
(310.15(B)(2)(a), Exception No. 6 (New))

Submitter: George Stolz, II, Pierce, CO
Recommendation: Add an Exception to read:
Exception No. 6: Of those conductors that are switched cable or raceway
installations, only the maximum number of conductors capable of being
simultaneously energized need to be derated.
Substantiation: In most threeway and fourway switching methods, the load is
alternated between travelers, eliminating the need to include both travelers in
derating.
Panel Meeting Action: Reject
Panel Statement: The proposed exception is not necessary. The present
language of 310.15(B)(2) already permits what the submitter is proposing.
Number Eligible to Vote: 11
Ballot Results: Affirmative: 11
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____________________________
 
Jim W in Tampa said:
I agree with Bobs logic but fact is NEC did not make an exception. Stupid as it is we must count it as 2. NEC says nothing about how often it is used. It is there to do what ? Carry current is its intent and it will. Not saying i think its right.
Click to expand...

Jim W in Tampa said:
Code referance that permits this ?
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Jim, the CMP unanimously disagrees with you.


6-50 Log #1405 NEC-P06 Final Action: Reject
(310.15(B)(2)(a), Exception No. 6 (New))

Submitter: George Stolz, II, Pierce, CO

Recommendation: Add an Exception to read:
Exception No. 6: Of those conductors that are switched cable or raceway installations, only the maximum number of conductors capable of being simultaneously energized need to be derated.

Substantiation: In most threeway and fourway switching methods, the load is alternated between travelers, eliminating the need to include both travelers in derating.

Panel Meeting Action: Reject

Panel Statement: The proposed exception is not necessary. The present language of 310.15(B)(2) already permits what the submitter is proposing.

Number Eligible to Vote: 11

Ballot Results: Affirmative: 11
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____________________________
 
Although some of the conductors may not carry current simultaneously, they are still physically present within the conduit and therefore reduce some of the air spacing between conductors.

Only thing I can think of.
 
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