Derate bundling MC cable ?

[dduffee260]

I know that if type NM cable is bundled for more than 24 inches it is required to be derated. What about type MC cable? Technically this is like conduit, I know you would not derate a bundle of 1/2" flex conduits, but MC cable is built so the wire is in contact with the outer shell. Let me have some input here. Thanks

 

[benaround]

Re: Derate bundling MC cable ?

BUNDLED: Cables or conductors that are physically tied,wrapped,taped,or otherwise periodically bound together.
def. in art.520.2

frank

 

[infinity]

Re: Derate bundling MC cable ?

Look at 310.15(B)(2) Exception No. 5, this is an exception where derating under the described conditions would not apply to type AC or MC cable.

[ May 10, 2005, 09:04 PM: Message edited by: infinity ]

 

[physis]

Re: Derate bundling MC cable ?

Take a look at 310.15(B)(2)Ex. 5 (courtesy Bob Badger, (something I learned from him)).

Edit: corrected code reference.

[ May 10, 2005, 09:07 PM: Message edited by: physis ]

 

[benaround]

Re: Derate bundling MC cable ?

Gentlemen,

310.15(B)(2)Ex#5 ----or to MC cable without an overall outer jacket---if all below conditions are met,
(a)each cable not more than 3 current carrying conductors i.e. CCC

(b) the conductors are # 12 AWG copper

(c) not more than 20 CCC are bundled,stacked,etc.

or a 60% adj. factor shall apply!!

Just so people don't get the wrong message.

frank

 

[physis]

Re: Derate bundling MC cable ?

I think this is a more important point.

What about type MC cable? Technically this is like conduit

No, it's not technically like like conduit. Although I've made the same misinterpretaion.

 

[vanwalker]

Re: Derate bundling MC cable ?

after reading this many times !!!?????
does this mean if you have 25 BUNDLED(w/o spacing) single circuit mc cables you must use 310.15(b)?? THANKS GEO

 

[infinity]

Re: Derate bundling MC cable ?

25, 12-2 wire MC cable would have a total of 50 current carrying conductors and would need to derated at 60% since it would contain more than 20 CCC's.

 

[vanwalker]

Re: Derate bundling MC cable ?

THANKS for your response?????
if 50 why not 35% SORRY for not getting it.THANKS GEO

 

[infinity]

Re: Derate bundling MC cable ?

310.15(B)(2)Ex#5 ----or to MC cable without an overall outer jacket---if all below conditions are met,
(a)each cable not more than 3 current carrying conductors i.e. CCC

(b) the conductors are # 12 AWG copper

(c) not more than 20 CCC are bundled,stacked,etc.

or a 60% adj. factor shall apply!!

By using exception #5 AC or MC cables when stacked or bundled are only required to be derated at 60%.

 

[dduffee260]

Re: Derate bundling MC cable ?

Originally posted by physis:
I think this is a more important point.

What about type MC cable? Technically this is like conduit

No, it's not technically like like conduit. Although I've made the same misinterpretaion.

Ok, so I know it is cable, but you can run it in wallsand above ceilings in a commercial building. You have to comply with straps every so often. The cable has to have the ground wire on a box. Flex conduit, which is conduit has to have a ground over 6 ft. So how can it not be considered a conduit? Is it because you already have the full amount of wire in it and cannot add any more wire?
Also, let's say you bundle it with a tie every 23 inches then there is some seperation between ty-wraps. Would this allow yu to go further and not be considered for derating?
Not that we do work like this, we mostly run EMT exposed and MC in walls. But is looks like more and more type MC cable is used entirely in small commercial projects.
Thanks, the answers we are getting are ineresting and helpful !!