MWBC...adjustment factor

[1793]

I'm trying to maximize the number of circuits in a conduit. I have three sets of 120v MWBC and I need all of the ampacity I can get. I'll have 10 conductors, 6 hots, 3 grounded, and 1 EGC. As I see it I'll have but only six(6)CCC. Yes / No?

 

[infinity]

What is the type of system that you're supplying these circuits with?

 

[220/221]

It has been argued that in a perfectly ballanced system the grounded conductors would not carry current.

 

[infinity]

For a 120/240 volt single phase system w/ 3 wire MWBC's you would have 6 CCC's.

For a 208Y/120 volt system you could have the minimum of 7 CCC's or maximum of 9 CCC's.

 

[1793]

What is the type of system that you're supplying these circuits with?

120/240 Single family dwelling, circuits for 2 Kitchen counter, Dishwasher/Disposer, lighting and Freezer.

 

[M. D.]

http://forums.mikeholt.com/showpost.php?p=916494&postcount=11

click the link I think it will help ....

 

[roger]

It has been argued that in a perfectly ballanced system the grounded conductors would not carry current.

It wouldn't need to be argued, barring issues such as harmonics, it is true however, even if the circuit is not balanced and barring the harmonic issue, the neutrals would still not need to be considered CCC's for the purpose of derating.

Roger

 

[infinity]

120/240 Single family dwelling, circuits for 2 Kitchen counter, Dishwasher/Disposer, lighting and Freezer.

You have 6 CCC's.

 

[1793]

You have 6 CCC's.

What I thought.

Thanks