310.15(B)(2) add Exception 6.

[iwire]

Re: 310.15(B)(2) add Exception 6.

Originally posted by charlie:
I like the concept and have made some suggested changes. We are ready for more comments and tweaking.

I also think this is a great idea, and would like to make few comments.

First is the following text what will be submitted?

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables ran in bored holes, or cut notches in joists or interior walls in dwellings under the following conditions:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use.

(2) Not more than 10 current carrying conductors are included in the bundle and are not larger that No. 12 Cu. or No. 10 Al.

4.) Substantiation: Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables, will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.

Why did "and where the ambient temperature will not exceed 30?C in normal use." get added?

I ask because IMO this proposed exception is very similar to an exception near and dear to me and there is no mention of ambient temps in it.

310.15(B)(2)Exception No. 5: Adjustment factors shall not apply to Type AC cable or to Type MC cable without an overall outer jacket under the following conditions:

(a)Each cable has not more than three current-carrying conductors.

(b)The conductors are 12 AWG copper.

(c)Not more than 20 current-carrying conductors are bundled, stacked, or supported on ?bridle rings.?

A 60 percent adjustment factor shall be applied where the current-carrying conductors in these cables that are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing exceeds 20.

I feel the proposal could simply ask for the addition of NM and tweaking to this existing exception.

IMO 310.15(B)(2) is already a convoluted article, the addition of yet another exception will exasperate that.

Here is what I imagine, my changes in bold.

310.15(B)(2)Exception No. 5: Adjustment factors shall not apply to Type AC cable or to Type MC cable without an overall outer jacket or to Type NM or UF cable under the following conditions:

(a)Each cable has not more than three current-carrying conductors.

(b)The conductors are 12 AWG or 14 AWG copper.

(c)Not more than 20 current-carrying conductors are bundled, stacked, run in bored holes in a wall, floor, or ceiling space or supported on ?bridle rings.?

A 60 percent adjustment factor shall be applied where the current-carrying conductors in these cables that are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing exceeds 20.

Substantiation: Where there are cables run in bored holes in joists, studs, etc snip, the maximum load on these cables, will most likely never be used because of the load profiles of 15 and 20 amp circuits snip. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.

I do wonder about my adding 14 AWG to the existing MC requirements?

This is not so easy.

What do you all think?

Wayne I hope you understand that I am not criticizing your efforts, I think you have a great idea.

Good luck to you with this.

Bob

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

By Bob: Why did "and where the ambient temperature will not exceed 30?C in normal use." get added?

I did say 40?C but I did have some concern as did Dave did with bundling in outside walls or attic spaces where the cables could be subject to much higher temp's. And Charlie lowered it to 30?C which seem's a little low but he's the engineer.

I do have a question for Charlie is why the 10 conductor limit as the code already allows for 9 current carrying conductors and I was thinking more to what Bob has in the requirement for AC cables? 20 I don't see this need if we are to only gain one current carrying conductor do you?

[ December 01, 2004, 07:42 PM: Message edited by: hurk27 ]

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

By Bob: Wayne I hope you understand that I am not criticizing your efforts, I think you have a great idea

Never Bob. I'm here to learn too

 

[don_resqcapt19]

Re: 310.15(B)(2) add Exception 6.

Bob,
There may have to be some reference to the new part of 334.80 in the 2005 code.
Don

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Ok how's this with my additions to Bob's in bold:

310.15(B)(2)Exception No. 5: Adjustment factors shall not apply to Type AC cable or to Type MC cable without an overall outer jacket or to Type NM or UF cable installed in a dwelling under the following conditions:

(a)Each cable has not more than three current-carrying conductors.

(b)The conductors are 12 AWG or 14 AWG copper.

(c)Not more than 20 current-carrying conductors are bundled, stacked, run in bored holes in a wall, floor, or ceiling space or supported on ?bridle rings.?

A 60 percent adjustment factor shall be applied where the current-carrying conductors in these cables that are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing exceeds 20.

This Exception shall not apply where more than two NM cables containing two or more current carrying conductors are bundled together and pass through wood framing that is to be fire- or draft stopped using thermal insulation or sealing foam, as required in 334.80

Substantiation: Where there are cables run in bored holes in joists, studs, etc snip, the maximum load on these cables, will most likely never be used because of the load profiles of 15 and 20 amp circuits snip. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.

[ December 04, 2004, 02:56 AM: Message edited by: hurk27 ]

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

Sorry, I have been tied up for a while so I will only address the last post.

310.15(B)(2)Exception No. 5: Adjustment factors shall not apply to Type AC cable or to Type MC cable without an overall outer jacket or to Type NM or UF cable installed in a dwelling under the following conditions:

It sounds like they all have to be installed in dwellings. I am not sure how to tweak that or if it really needs to be tweaked.

(b)The conductors are 12 AWG or 14 AWG copper.

Now you are changing the rules for Type MC cable with no substantiation for doing so.

(c)Not more than 20 current-carrying conductors are bundled, stacked, run in bored holes in a wall, floor, or ceiling space or supported on ?bridle rings.?

Nothing is said about insulation in the walls, floor or ceiling space and this applies to MC cable. The paragraph you are adding would only apply to Type NM cables and not to Type UF or MC cables.

I really think you need to make a separate exception for Type NM and UF cables.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

This is a really big thread and I haven't read more than half of it. But I was thinking that this proposal could have an undesireable side effect.

You guys sometimes use an odd kind of logic in interpretting codes. Usually associated with exeptions. When something is specificly allowed by exeption it's taken as implied that outside of that exeption the opposite must be true.

Is there a danger that the nonexistant need for derating where it's not required will acctually be reenforced outside of the exeption?

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

Sam, there is always the danger of misinterpretation. However, each item a person is trying to get by with or the AHJ is trying to enforce must be backed up by the words of the Code, not by inference. You will always say that something is not in compliance with the Code, not that the Code infers that something is not in compliance.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

Well Charlie, It's interesting you put it that way because that also applies to proposed change.



Edit: I mean the proposed exception is to eliminate a misinterpretaion caused by inference. Isn't it?

[ December 05, 2004, 06:44 PM: Message edited by: physis ]

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

Sam, proposals are also made to correct what AHJs are enforcing if you do not agree with them. Sometimes the panel will turn a proposal down on the grounds that it already says what you want it to do. In those cases, the panel will write a statement that serves as an official interpretation. In other cases, the panel may rewrite the rule to make it more clear. This is part of the reason that the Code is so big and is not getting any smaller.

 

[physis]

Re: 310.15(B)(2) add Exception 6.

Good morning Charlie,

I'm just jumping up and down on it a little to see how it holds up.

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

My 2005 Edition is hardbound so it will hold up pretty good.

 

[rbalex]

Re: 310.15(B)(2) add Exception 6.

Originally posted by charlie:
I'll give you a list of some that I like to use. Hold down the ALT key while you type in the whole number on you key pad.

0169 ? Copyright
0174 ? Registered
0176 ? Degree
0177 ? Plus or Minus
0178 ? Superscript 2
0179 ? Superscript 3
0185 ? Superscript 1
0188 ? 1/4
0189 ? 1/2
0190 ? 3/4
0216 ? Phase mark

Use your notepad and you can see what other symbols can be made.

This would be great FAQ stuff; if only we had some way to create "strikeout" text.

BTW: Wayne, are we at a point where you feel you have your "final" version? If yes, I'll close out this thread. If not, we can continue as long as you want. The goal is to help the submitter create a strong Proposal.

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Sorry for not getting back right away as I was under the weather. (Rain, cold, rain, cold yuk!)

I Wasn't sure if this is what I should submit. Or Bob's version as Charlie think's it would be better to keep NM/UF separate from the AC cable.

But I would like input as to why it is needed to keep the amount of conductors to only 10 as the code is now we are allowed 9 current caring conductors with the derating from table 310.16 using the allowed 90?C column now? Adding 1 conductor would not seem to gain enough leeway to require the change?

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables ran in bored holes, or cut notches in joists or interior walls in dwellings under the following conditions:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use.

(2) Not more than 10 current carrying conductors are included in the bundle and are not larger that No. 12 Cu. or No. 10 Al.

4.) : Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables, will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.

Another substantiation that could be added:
Is that the fact that in commercial environments 15 and 20 amp. circuits are ran for specific planed loads, but in a residential environment 15 and 20 amp. circuits are ran for convenience and most likly will never be loaded to the max.

Ok any more thought's?

[ December 06, 2004, 08:32 PM: Message edited by: hurk27 ]

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

I can see the following:

(2) Conductors included in the bundle are not larger that No. 12 Cu. or No. 10 Al.

This could be argued that the dwelling unit load is so diverse and that those circuits are almost totally for convenience; therefore, the need for derating is not required as circuits will be used minimally and in small groups. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. Those circuits, mixed in with the other circuits, would not require derating.

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Ok one last time for final tweeking.

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables ran in bored holes, or cut notches in joists or interior walls in dwellings under the following conditions:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use.

(2) Are not larger that No. 12 Cu. or No. 10 Al.

4.) : Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables, will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.
And that the dwelling unit load is so diverse and that those circuits are almost totally for convenience; therefore, the need for derating is not required as circuits will be used minimally and in small groups. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. Those circuits, mixed in with the other circuits, would not require derating.

Charlie is this what you envisioned?

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

Yes but after seeing it in total, I wasn't seeing the sun when I put the second statement together. It should read:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use and;

(2) where these cables are not larger that No. 12 Cu. or No. 10 Al.

 

[hurk27]

Re: 310.15(B)(2) add Exception 6.

Ok how's this:

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables run in bored holes, or cut notches in joists or interior walls in dwellings under the following conditions:

(1) Where these cables are run in bored holes in a wall, floor, or ceiling space, and where the ambient temperature will not exceed 30?C in normal use and.

(2) Where these cables Are not larger than No. 12 Cu. or No. 10 Al.

4.) : Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables, will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs and building regulations limit the amount of these holes that can be safely bored into floor joist. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.
And that the dwelling unit load is so diverse and that those circuits are almost totally for convenience; therefore, the need for derating is not required as circuits will be used minimally and in small groups. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. Those circuits, mixed in with the other circuits, would not require derating.

 

[charlie]

Re: 310.15(B)(2) add Exception 6.

I feel like I am really belaboring the process. What do you think about this?

Exception No. 6: derating factors shall not apply to cables run in bored holes, or cut notches in joists or interior walls in dwellings under all of the following conditions:

(1) Where these cables are installed in wall, floor, or ceiling spaces that have no insulating material

(2) Where the ambient temperature will not exceed 30?C in normal use

(3) Where these cables are not larger than No. 12 Cu. or No. 10 Al.

Sorry Wayne, every time I look at this I see something else.

 

[George Stolz]

Re: 310.15(B)(2) add Exception 6.

Thoughts from a small mind: I really like this. Many panels are installed in garage walls and this could provide protection for them, if the insulation hang-up was removed. My other thought was that the cables' individual articles already denote acceptable installation methods, so it might be duplicative. And I like to pick things apart and try them different ways grammatically, my apologies. It's probably OCD. Here is a different way of wording it...

1.) NEC Section/Paragraph: 310.15(B)(2) add Exception 6.

2.) Proposal Recommends: [new text]

Exception No. 6: derating factors shall not apply to cables installed in joists or interior walls in dwelling units under all of the following conditions:

(1) Where these cables are installed in wall, floor, or ceiling spaces where the ambient temperature will not exceed 30?C in normal use

(3) Where these cables are not larger than No. 12 Cu. or No. 10 Al

4.) : Where there are cables run in bored holes in joists with spacing between each joist, the maximum load on these cables will most likely never be used because of the load profiles in dwelling units. The temperature rise of these cables is minimal under these conditions. By limiting this exception to 15 and 20 ampere circuits, the range, dryer, electric furnace, etc. are excluded and the likelihood of more than one or two heavily loaded circuits are eliminated.

The code now requires multiple holes to be bored in floor joists to accommodate the runs. Building regulations limit the amount of these holes that can be safely bored into floor joists. This places an undue burden on the electrician to find exit routing from panelboards. This proposal will provide some relief from the stringent requirements.

In addition the dwelling unit load is so diverse that those circuits are almost totally for convenience; therefore, derating becomes redundant as circuits will be used minimally and in separate locations. The heaviest loaded circuits would likely be one or two small appliance branch circuits, a bathroom receptacle circuit, and a laundry circuit. This mix of moderately used and unused circuits would not require derating.