Bundled = Derated

[iwire]

Re: Bundled = Derated

If I bundle four 14/2 cables together then yes they get derated.

Four - two wire cables will be 8 current carrying conductors.

334.80 tells us NM can derated using the 90 C column of Table 310.16

Table 310.16 rates 14 AWG as 25 amps @ 90 C.

Table 310.15(B)(2)(a) shows that 8 current carrying conductors suffers an 70% ampacity reduction.

25 amps * .7 = 17.5 derated ampacity.

So my four 14/2 NMs through one hole will still be perfectly compliant.

[ September 21, 2005, 05:12 PM: Message edited by: iwire ]

 

[iwire]

Re: Bundled = Derated

Originally posted by bassphisher:
And I consider the cables bundled in the panel if they are ty-raped.

They are not subject to derating unless bundled for longer than 24"

310.15(B)(2) Adjustment Factors.
(a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a).

[ September 21, 2005, 05:11 PM: Message edited by: iwire ]

 

[bassphisher]

Re: Bundled = Derated

I totally agree.As I said in my first post I allow up to 4-2 wire (8 conductors total)cables without any problem

 

[bassphisher]

Re: Bundled = Derated

I believe that we are over 24" if you add the length of the panel plus the nipple out of the top.

 

[iwire]

Re: Bundled = Derated

Originally posted by bassphisher:
I totally agree.As I said in my first post I allow up to 4-2 wire (8 conductors total)cables without any problem

Paul, you had a typo here so I was confused.

Originally posted by bassphisher:
I think that everyone needs to read 334.80. It only allows for 2 nm cables.

So now that I understand you where talking about four cables I see we agree.

 

[tom25]

Re: Bundled = Derated

if you are referring to a single family dwelling...
you need to lighten up and realize what needs to be changed in the NEC.
The de-rating tables were developed with continuous loads.

 

[infinity]

Re: Bundled = Derated

And I consider the cables bundled in the panel if they are ty-raped.

So are you saying that you would require derating for cables bundled in a panel?

What about:

310.15(2)Exception: Where two different ampacities apply directly to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the transition, a distance equal to 3.0m(10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less.

Wouldn't this just about negate any derating for bundled conductors in a panelboard? If the conductors were bundled for say 4' and if the circuits were at least 40' long no derating would apply due to the heat sink effect of the conductors.

 

[iwire]

Re: Bundled = Derated

Trevor you will make Ryan smile with that reference.

 

[allenwayne]

Re: Bundled = Derated

Bundling,Bundling,Bundling this same topic keeps poping up.Running through bored holes in this manner IMHO is fine.To me bundling becomes an issue when you staple more than 9 current carrying conductors in a 24 in space,like coming down a stud to a multi gang box.Two choices there split the cables into 2 sets with each not breaching that magical number.
Or # 2`s option use stackers,Since 95% of the homes here are block and furring,we use quite alot of stackers each year

 

[George Stolz]

Re: Bundled = Derated

Originally posted by iwire:

Originally posted by bassphisher:
And I consider the cables bundled in the panel if they are ty-raped.

They are not subject to derating unless bundled for longer than 24"

310.15(B)(2) Adjustment Factors.
...More Than Three Current-Carrying Conductors in a Raceway or Cable
...bundled longer than 600 mm (24 in.)...

Is a panel a cable, or a raceway? I don't think this code applies to conductors inside a panel.

 

[iwire]

Re: Bundled = Derated

Originally posted by georgestolz:
Is a panel a cable, or a raceway? I don't think this code applies to conductors inside a panel.

Good point.

IMO it depends.

A panel may be a raceway per 312.8 or it may just be a panel.

 

[ryan_618]

Re: Bundled = Derated

Originally posted by iwire:
Trevor you will make Ryan smile with that reference.

That is why I have proposed to delete the nonsensical second paragraph of 334.80 for the 2008 cycle. We'll see what happens

 

[bassphisher]

Re: Bundled = Derated

Excuse me but what is IMHO?

 

[dillon3c]

Re: Bundled = Derated

"in my honest opinion"..

 

[bassphisher]

Re: Bundled = Derated

Thanks for the info.

 

[bassphisher]

Re: Bundled = Derated

Check out page 58 in the Analysis of Changes 2005 NEC.Sorry that I can not give you more information on this book but I only have copy pages that were handed out at a meeting

[ September 22, 2005, 10:01 AM: Message edited by: bassphisher ]

 

[iwire]

Re: Bundled = Derated

Originally posted by bassphisher:
Check out page 58. in the Analysis of Changes 2005 NEC

I will but check it about what specifically?

 

[bphgravity]

Re: Bundled = Derated

Page 58? This page covers the change to Section 225.30(A).

 

[charlie b]

Re: Bundled = Derated

Originally posted by bassphisher: Excuse me but what is IMHO?

Originally posted by dillon3c: "in my honest opinion"..

I would have said, "In My Humble Opinion." But then, like Uriah Heap, "I am so very umble."

 

[dillon3c]

Re: Bundled = Derated

Originally posted by charlie b:

But then, like Uriah Heap, "I am so very umble."