3CCC In A Conduit

[mstrlucky74]

I was tolf that this is Code....3 current carrying conductors in a conduit.....Is that true? I see it spec'ed a lot but that's it.

 

[Little Bill]

I was tolf that this is Code....3 current carrying conductors in a conduit.....Is that true? I see it spec'ed a lot but that's it.

Probably what was speced was you can have 3 CCC in a raceway before having to derate.
You can have many more than that (depending on conductor & raceway size) but have to start derating after 3.

 

[Smart $]

I was tolf that this is Code....3 current carrying conductors in a conduit.....Is that true? I see it spec'ed a lot but that's it.

Not a Code limitation. I've also seen many spec's which limit CCC's to three in a conduit.

 

[lakee911]

One can have more than 3 CCC in a conduit by code. Probably engineer's requirement (spec) so equipment feeds remain isolated.

 

[GoldDigger]

One can have more than 3 CCC in a conduit by code. Probably engineer's requirement (spec) so equipment feeds remain isolated.

But taken as an absolute, this would mean that you could never use a 3-phase MWBC for line to neutral high harmonic content luminaires.
All of the circuit conductors would have to go in the same raceway, and it would have 4 CCCs. Nor could you put two sets of 3-way travelers in one raceway

 

[iwire]

But taken as an absolute, this would mean that you could never use a 3-phase MWBC for line to neutral high harmonic content luminaires.

Yes and some EEs don't want us to use MWBCs.

Nor could you put two sets of 3-way travelers in one raceway

That would only be two CCCs. The CMP has confirmed this via previous code change proposals.

 

[GoldDigger]

Yes and some EEs don't want us to use MWBCs.




That would only be two CCCs. The CMP has confirmed this via previous code change proposals.

Unfortunately, rejecting a proposal to clarify the code on the grounds that it is not necessary is not quite the same as clarifying the code. The exact interpretation of the words in the code does not support an exemption for two conductors that cannot carry current simultaneously.

 

[iwire]

Unfortunately, rejecting a proposal to clarify the code on the grounds that it is not necessary is not quite the same as clarifying the code. The exact interpretation of the words in the code does not support an exemption for two conductors that cannot carry current simultaneously.

Fortunately that is up to the AHJ.

 

[GoldDigger]

Fortunately that is up to the AHJ.

:thumbsup:

 

[mwm1752]

I'm still stuck at tolf -- :blink: oh told

 

[electrofelon]

Yes and some EEs don't want us to use MWBCs.




That would only be two CCCs. The CMP has confirmed this via previous code change proposals.

Hold on, there is a debate about how many ccc are in a three way? Someone fill me in.

 

[iwire]

Hold on, there is a debate about how many ccc are in a three way? Someone fill me in.

There has been.

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

 

[GoldDigger]

Hold on, there is a debate about how many ccc are in a three way? Someone fill me in.

Some argue that in the absence of a special provision, such as for MWBC neutral and EGC, you count each conductor that will carry current at some time, not necessarily at the same moment in time as other conductors.
It does not make much practical sense, but it sure simplifies the counting process and gives a conservative result.
So by that argument the two travelers of a three way switch middle leg and even the neutral that just goes to the switch location for presence sensors have to be counted.

Although it is possible that, by virtue of not formally defining CCC at all, 310.15(B) allows for only one of each traveler pair to be counted, I sure do not see that expressed clearly anywhere.
I am with George on that one for sure.

 

[jusme123]

Fortunately that is up to the AHJ.

AHJ job is to enforce the code as written, not make up rules as they see fit. JMO

 

[iwire]

AHJ job is to enforce the code as written,

Of course it is.

But it also their job to interpret it.

90.4 Enforcement. This Code is intended to be suitable
for mandatory application by governmental bodies that exercise
legal jurisdiction over electrical installations, including
signaling and communications systems, and for use by
insurance inspectors. The authority having jurisdiction for
enforcement of the Code has the responsibility for making
interpretations of the rules, for deciding on the approval of
equipment and materials, and for granting the special permission
contemplated in a number of the rules.

By special permission, the authority having jurisdiction
may waive specific requirements in this Code or permit
alternative methods where it is assured that equivalent objectives
can be achieved by establishing and maintaining
effective safety.

This Code may require new products, constructions, or
materials that may not yet be available at the time the Code
is adopted. In such event, the authority having jurisdiction
may permit the use of the products, constructions, or materials
that comply with the most recent previous edition of
this Code adopted by the jurisdiction.

I think it is pretty clear that there is more than one interpretation of the section we are discussing.

 

[electrofelon]

That would only be two CCCs......

Ok your statement threw me off, looks like it was a theoretical scenario. I was assuming the "two sets of travelers" as mentioned would have the associated conductors with them too since all conductors must be in same raceway or cable so I was wondering how the heck you and the cmp were getting two. I wonder if in the history of electricity anyone has ever wired two three way circuits that are fed and loaded at opposite ends and on a split phase system as a "multiwire" to avoid derating? That would be fun.

 

[iwire]

Ok your statement threw me off, looks like it was a theoretical scenario. I was assuming the "two sets of travelers" as mentioned would have the associated conductors with them too since all conductors must be in same raceway or cable so I was wondering how the heck you and the cmp were getting two. I wonder if in the history of electricity anyone has ever wired two three way circuits that are fed and loaded at opposite ends and on a split phase system as a "multiwire" to avoid derating? That would be fun.

Picture a lighting outlet on the ceiling, that box has the feed in it. From that box you run two three wire cables,one to each three way location. This is something I might do if snacking the cables to old work switch boxes.

The cable to each three way would have 3 circuit conductors but only two current carrying conductors.

You can expand that example to multiple outlets with multiple switches at each door run in pipe.

 

[Little Bill]

This is something I might do if snacking the cables to old work switch boxes.

You must be in a Super Market again on the midnight shift, looking for a snack!:lol: