Bundling Multi Neutral MC cable

[scottam99]

I am reading the exception 315 (B) 2a Exception # 5. It states that Adjustment factors shall not apply if each cable has no more than 3 current carrying conductors.
Am I right to assume that if I am installing 12-3-3 ( 3 hots, 3 neutrals in each MC cable) i have to derate no matter what? So If I install 2 of this type MC I already have 12 Current carrying conductors. I would have to increase wire size to number 10's?
Additionally I would have to derate if I am using #10-3-3 ( 3 hots, 3 neutrals in each cable ) for voltage drop no matter how many cables I am installing?

 

[iwire]

I see it the same way.

Any reason not use a multiwire branch circuit to cut the number of current carrying conductors in half?

 

[infinity]

I am reading the exception 315 (B) 2a Exception # 5. It states that Adjustment factors shall not apply if each cable has no more than 3 current carrying conductors.
Am I right to assume that if I am installing 12-3-3 ( 3 hots, 3 neutrals in each MC cable) i have to derate no matter what? So If I install 2 of this type MC I already have 12 Current carrying conductors. I would have to increase wire size to number 10's?
Additionally I would have to derate if I am using #10-3-3 ( 3 hots, 3 neutrals in each cable ) for voltage drop no matter how many cables I am installing?

The 12-3-3 cable by itself requires derating. As you've said bundle two of them together and you need to go down to 50% ampacity. #10 MC doesn't fall under the exception so the normal derating rules apply.

 

[scottam99]

This is for a hotel new construction. Each unit in the hotel to have 3 circuits. I don't think it would be wise to use 3 pole breakers for unit wiring. Therefore I will need a neutral for each hot.